ATV-DVWK-A 116, Part 1________________________
ATV - DVWK A set of rules and standards
WORKSHEET ATV-DVWK-A 116 Special drainage procedures/systems Part 1: Vacuum Drainage outside of buildings
April 2004
Deutsche Vereinigung für Wasserwirtschaft, Abwasser und Abfall e.V., ATV-DVWK
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April 2004
ATV-DVWK-A 116, Part 1________________________
ATV-DVWK A set of rules and standards
WORKSHEET ATV-DVWK-A 116 Special drainage procedures/systems Part 1: Vacuum Drainage outside of buildings April 2004 ISBN 3-937758-15-1
ATV-DVWK
Deutsche Vereinigung für Wasserwirtschaft, Abwasser und Abfall e.V. Theodor-Heuss-Allee 17 – D-53773 Hennef Telefone: 02242/872-0 – Fax 02242/872-135 E-Mail:
[email protected] - Internet: www.atv.de
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April 2004
ATV-DVWK-A 116, Part 1________________________ The Deutsche Vereinigung für Wasserwirtschaft, Abwasser und Abfall e.V., ATV-DVWK, is official spokesman in Germany for all global questions concerning water and sets up intensely for the development of a secure and sustainable water supply and distribution. As politically and economically independent organisation it is active in the following special sections i.e. water supply and distribution, waste water, removal of waste and soil conservation. In this field the ATV-DVWK is in Europe the union with the greatest number of members and is holding a special position due to its competence concerning standardization, professional education, and information of the public. The number of approx. 15.000 members represent specialists and leaders out of communities, high schools, engineering offices, authorities and companies. Its activities focus on compiling and updating of a uniform technical set of standards as well as the cooperation in gathering specialist standards on national and international level. Besides technical-scientific subjects/topics also economic and legal interests are included. IMPRINT Publisher/Distributor:
Composition/Print:
ATV-DVWK Deutsche Vereinigung für WasserWirtschaft, Abwasser und Abfall e.V., Theodor-Heuss-Allee 17 53773 Hennef
DCM, Meckenheim
Tel.: Fax: E-Mail: Internet :
ISBN: 3-937758-15-1
02242 / 872-120 02242 / 872-100
[email protected] www.atv-dvwk.de
Printed on 100 % recycled paper
© ATV-DVWK Deutsche Vereinigung für Wasserwirtschaft, Abwasser und Abfall e.v., Hennef 2004 All rights, in particular those of translation into other languages, are reserved. No part of this Standard may be reproduced in any form by photocopy, microfilm or any other process or transferred or translated into a language usable in machines, in particular data processing machines, without the written approval of the publisher. The publisher does not assume any responsibility of the scientific correctness of the texts, illustrations and tables.
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ATV-DVWK-A 116, Part 1________________________ Preface Following the mandate of the commission of the European Union (KEU) and the European Free Trade Association (EFTA) dd. 24th May 1991 the Comité Européen de Normalisation (CEN) has assumed the task of adapting all technical rules concerning wastewater technology and compiling European Standards for prefixed sections and products. In 1997 DIN EN 1091 “Vacuum Drainage Systems outside of Buildings” and DIN EN 1671 “Pressure Drainage Systems outside of Buildings” have been published after protrunked and tedious negotiations under busy German participation and after having treated numerous objections. Both set of standards contain general requirements concerning the performance of the systems as well as determination of when the checks have to be done, they contain as well special requirements on the products to be used. In addition it is possible to formulate commitments which are not or not fully contained in European Standards in order to cover / satisfy contents required by federal authorities. The present work sheet shall help the consulting engineer to find out the margins as described in DIN EN 1091 and to use them creatively. The application of DIN EN 1091 shall be facilitated. There is no substantial contradiction between the new European Standards and the Work Sheet ATV-A 116 from 1992 used up to now since it contains nearly exclusively requirements for the planning and dimensioning of the systems and only a few requirements on the products. Besides this it was possible to include the ATV-Work Sheet in large areas as a base for the compilations on both European Standards. The labour report from 2000 cited in the appendix G as literature contains a comparison of DIN EN 1091 with the Work Sheet ATV-A 116 from 1992 used up to now and may serve as orientation. Nevertheless the ATV-DVWK-working group ES-2.3 undertook the revision and continuation of the Work Sheet ATV-A 116 in order to take into account changes out of new European Standards as well as technical progressive developments and new experiences. Now the Work Sheet ATV-DVWK-A 116 consists of: • • •
Part 1: Vacuum drainage systems outside of buildings Part 2: Pressure drainage systems outside of buildings Part 3: Compressed air cleansed pipelines for the transport of wastewater
European Standards contain part 1 and 2. As for part 3 there is a labour report dd. 1987 (see appendix H). The present Work Sheet is meant for planners, those who offer respective systems, authorities, operating companies and construction firms. The present part 1 is equal to the arrangement of the European Standard DIN EN 1091 in order to facilitate the consulting of both documents simultaneously. Appendix M contains the useful life and appendix N the requirements on the qualification / training of the construction and company staff.
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ATV-DVWK-A 116, Part 1________________________ Publisher The ATV-DVWK-Working Group ES-2.3 “Special Drainage Systems” in the ATV-DVWKspecial committee ES-2 “Planning according to the system requirements” which has prepared the present Work Sheet consists of the following members: Baudirektor Dipl.-Ing. Helmut Bieber, Kiel Dipl.-Ing. Walter Dippold, Germering Prof. Dr.-Ing. hab. Hartmut Eckstädt, Rostock Bauassessor Dipl.-Ing. Karl-Heinz Flick, Köln Dr.-Ing. Harald O. Howe, Köln (bis 2000) Ministerialrat Dipl.-Ing. Jens Jedlitschka, München (Sprecher) Prof. Dr.-Ing. Adolf Kleinschroth, München (†) Dipl.-Ing. Angela Klippel, Berlin Dipl.-Ing. Thomas Petersohn, Aurich Dr.-Ing. Markus Roediger, Charlotte (NC, USA)
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ATV-DVWK-A 116, Part 1________________________ Contents Introduction
........................................................................................................3
Publisher
........................................................................................................4
Hints for the user ........................................................................................................7 1
Field of application ......................................................................................7
2
Standard hints..............................................................................................7
3
Definitions ....................................................................................................7
4
System descriptions....................................................................................7
4.0
General ........................................................................................................7
4.1
Collection chamber and vacuum line.............................................................8
4.2
Vacuum station ..............................................................................................9
5
Requirements...............................................................................................9
5.0
Statutory questions ........................................................................................9
5.1
General requirements ....................................................................................9
5.2
Special requirements on components ...........................................................9
5.2.1
Gravity lines ...................................................................................................9
5.2.2
Sewage drainage out of connected waterways and industrial settlements ...9
5.2.3
Domestic connection chamber ....................................................................10
5.2.4
Collection chambers ....................................................................................10
5.2.5
Evacuation valve..........................................................................................10
5.2.6
Level indicator..............................................................................................10
5.2.7
Valve control ................................................................................................10
5.2.8
Explosion-proof (Domestic connection chamber) ........................................10
5.2.9
Tool/Endurance life of diaphragms and seals..............................................10
5.2.10
Components of vacuum lines ......................................................................10
5.2.11
Dimensions of pipes ....................................................................................11
5.2.12
House connection lines................................................................................11
5.2.13
Connection of subsidiary pipelines (Branching of vacuum lines).................11
5.2.14
Cut-off devices.............................................................................................11
5.2.15
Vacuum vessels...........................................................................................11
5.2.16
Control of vacuum station ............................................................................12
5.2.17
Filling level supervision................................................................................12
5.2.18
Equipment / Vacuum production..................................................................12
5.2.19
Operational capacity of onward conveyance facilities ................................12
5.2.10
Construction of feeding pump......................................................................12
5.2.21
Exchange of feeding pumps ........................................................................12
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ATV-DVWK-A 116, Part 1________________________ 5.2.22
Explosion-proof (vacuum station) ................................................................12
5.2.23
Check-valve devices....................................................................................12
5.2.24
Propulsion-jet ejectors .................................................................................12
5.2.25
Odour reduction ...........................................................................................12
5.2.26
Noise reduction............................................................................................13
5.2.27
Emergency power unit .................................................................................13
5.3
Requirements on the planning.....................................................................13
5.3.0
General ......................................................................................................13
5.3.1
Dimensioning of the lines.............................................................................13
5.3.2
Height profile of the lines .............................................................................13
5.3.3
Hydro-pneumatic lay-out..............................................................................15
5.3.4
Fundamental principles for lay-out...............................................................16
5.3.5
Vacuum station ............................................................................................16
5.3.6
Source of additional information ..................................................................17
5.3.7
Application fields for vacuum drainage systems..........................................17
6
Laying of pipelines ....................................................................................17
6.1
Laying of pipelines .......................................................................................17
6.2
Tolerances ...................................................................................................18
6.3
Warning and locating devices......................................................................18
7
Checks ......................................................................................................18
8
Initial operation (Acceptance) ..................................................................18
9
Economic aspects .....................................................................................18
Appendixes A till E:.....................................................................................................19 Appendix F:
Information on operation and maintenance ............................19
Appendix G:
Sources for additional information ...........................................19
Appendix I:
Application of vacuum sewerage systems...............................22
Appendix K:
Rating example ...........................................................................22 K 1 Settings...................................................................................22 K 2 Dimensioning of the pipeline network .....................................22 K 3 Dimensioning of the vacuum station.......................................26
Appendix L:
Explication of signs ....................................................................27
Appendix M:
Life-cycles ...................................................................................28
Appendix N:
Qualification/Training of staff ....................................................29
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ATV-DVWK-A 116, Part 1________________________ Considerations for use This work sheet results from a technical-scientific-economic teamwork on a voluntary basis built on the principles valid for this set of rules and standards (statutes and business rules of the ATV-DVWK and the ATV-DVWK-A 400). According to the legal situation there is a real assumption that its contents is correct also for the technical aspect as well as accepted in general. Everyone is free to use the contents of this work sheet or not. However, there might occur an obligation to apply them due to legal and administrative regulations, contracts or other legal reasons. This sheet is an important, however not unique source of knowledge to find out the right professional solutions. Through the application of the Rules and Standards no one avoids responsibility for his own actions, especially as for the correct professional handling of the margins shown in this work sheet.
1
Field of Application
This work sheet completes DIN EN 1091 “vacuum drainage systems outside of buildings” and is valid only in connection with this Standard. The work sheet ATV-DVWK-A 116, part 1 is meant for the planning, construction and operation of vacuum sewerage systems outside of buildings and contains further regulations and hints.
2
Normative Hints
See Appendix G: Sources of additional information.
3
Definitions
To complete the definitions of DIN EN 1091 and DIN EN 1085 the following definitions are valid: 3.3 Collection room: As defined in DIN EN 1091, however includes an emergency retaining room. 3.18 Evacuation unit: Consists of an evacuation valve, a controlling device as well as the respective accessories. 3.19 Population density (EDL) per unit length: Number of the population values connected to a main line as for the number of sinks taking into consideration all other side lines, divided by the length of the main line. 3.20 Main line: Vacuum canal (collection line) from the vacuum station up to the house connection situated at the greatest distance, without subsidiary lines. 3.21 Air/water ratio (LWV): Ratio of the air volume suctioned or airflow under standard conditions to the wastewater volume suctioned or sewage flow.
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ATV-DVWK-A 116, Part 1________________________ 4
Description of System
4.0
General
The low-pressure system, also known as vacuum system or vacuum sewer system, was already been invented by the Dutch technician Liernur and employed at the end of the last century (1) in one or two places, mainly in cities such as Amsterdam, Paris and Berlin (2,3). The technology has been taken up again by the Swedish specialist Liljendahl at the beginning of the 50 Fifties in the 20th Century. Since the end of the Sixties vacuum drainage has been employed with success also in many places in the Federal Republic of Germany (4,5,6,7). Last decade components and rating procedures have been refined and developed further-on considerably. The vacuum evacuation technology contains closed pipeline networks without manholes. The high transport velocity of the air/water-mixture in the vacuum pipelines prevents sediments. Normally the vacuum drainage technology serves as collection of wastewater in separate systems. An outlet of wastewater is excluded due to the vacuum occurring inside the system. Therefore, it is allowed to lay out vacuum pipelines together with potable water lines in a common ditch as well as in water preservation areas without any further protective measures (see also ATV-DVWK-A 142). Varying from DIN EN 1091 the procedure can also be used in the industrial and commercial sector. The application of this system offers itself for •
Rural areas (see also ATV-DVWK-A 200)
•
Insufficient terrain slope
•
Connections to lower situated part of a village or buildings
•
Obstacles to be by-passed (for ex. rivulets, ditches, supply pipelines)
•
High groundwater table
•
Low population density
•
Adverse sub-surface conditions
•
Water preservation areas
•
Places where wastewater occurs only intermittently (for ex. camping sites or weekend house areas)
•
Places where impairments have to be kept low (for ex. traffic, buildings, soil)
The vacuum evacuation technology is a special drainage procedure which might - under certain circumstances - be considerably cheaper than the conventional gravity lines sewage system. Investment costs can be considerably lower in comparison with other drainage procedures. Cost comparison charts should consider all follow-on costs as for depreciation
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ATV-DVWK-A 116, Part 1________________________ (write-off), interests, operation and maintenance (15). Please pay attention to the fact that storm water is not normally disposed of in this manner. Vacuum lines form a ramification network with a central vacuum station (figure 1). The length of main branches is up to 4 km in case of plain terrain. In case of ascending terrains into flow direction the length is shorter and it can be longer in case of descending areas. Larger areas can be subdivided into single sectors with their own vacuum stations and connected for instance via pressure-lines.
Connected House with Collection Chamber
Main Line
Vacuum Station VS WWTP
Outfall Ditch
Branch Line
Figure 1: Diagram of a vacuum drainage system
4.1
Collection chamber and vacuum line
The transition from the conventional gravity line of a domestic installation into the vacuum line takes place inside the evacuation valve. In general it is placed outside the house in a shaft, but it can also be installed in the cellar. Vacuum toilets can be connected directly to vacuum lines inside buildings - other sanitary objects must be connected via evacuation units. In this case please read DIN EN 12109 “Vacuum drainage systems inside of buildings”. In case of systems with pneumatic evacuation valve units a supply point for electrical current is necessary for the vacuum station only. However, in case of electrical-hydraulic evacuation valve units each domestic connection shaft needs a supply point for electrical current. On opening the evacuation valve wastewater and air are sucked into the vacuum line and flow through the pipe in the direction of the vacuum station. The medium air/water-ratio of vacuum systems based on available operating experience is approx 3:1 up to 15:1. It increases according to a bigger branch/trunk length accompanied with a height difference to be overcome. When the evacuation valve units are placed at the end of the trunk, the
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ATV-DVWK-A 116, Part 1________________________ air/water-ratio is adjusted at a higher triggering point than in cases when they are placed nearer to the vacuum station.
4.2
Vacuum Station
The necessary under pressure for operation of normally 60 to 70 kPa resp. 0,6 to 0,7 bar (40 till 30 kPa absolute pressure) is developed and maintained in the vacuum station by means of vacuum pumps in one or several vacuum vessels/reservoirs. Then wastewater is conveyed/ transported for further treatment of sewage for instance by means of pumps or pneumatic conveyance devices. Vacuum stations normally lie centrally within its allotted drainage area. With this, at the same time, the location in a low point on the ground is to be sought. Due to odour and noise emanations sufficient separation from the surrounding buildings is recommended. The size of the separation in detail is based on the type and position of the surrounding buildings as well as on measures for acoustic insulation and odour reduction.
5
Requirements
5.0
Statutory Questions
It has proved practical to have the procurement, servicing and maintenance of the valve units and the shafts carried out by the concern providing the vacuum drainage system. Insofar as these facilities are on private property an appropriate agreement is necessary, if required, with legal safeguards in the statutes or bye-law. The following statement in the drainage statutes is possible: If wastewater from a private property is fed into a pressure drainage system the owner is to allow the establishment, on his property, of the facilities which serve to collect and transport the wastewater as well as the connection pipelines between these facilities and the boundary of the property. The same applies for the operation and maintenance as well as for the necessary repair, modification and renewal work. Type and location of the facilities are determined by the responsible authorities and its authorized staff. Conduits and shafts may not be built upon. Defects in the facilities for collection and transportation of the wastewater which are noted by the owner of the property or another user are to be reported to the responsible operator. The landowner is to allow the employees of the responsible operator/agency and those authorized by it access to the facilities and pipelines at any time.
5.1
General requirements
In case of back flooding out of the collection reservoir measures have to be taken in order to prevent inundation of buildings (see DIN 1986).
5.2
Special requirements to components
5.2.1
Gravity lines
The domestic installation must be ventilated according to DIN EN 12056. DIN 1986-100 is valid for drainage facilities of buildings and land properties.
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ATV-DVWK-A 116, Part 1________________________ It must be sure that only quantities of wastewater is forwarded into the collection rooms.
5.2.2
Outlets from connected canalisation and commercial settlements
In places where more than 20 inhabitants are to be connected for discharge due to reasons of operational safety a domestic connection chamber has to be equipped with several evacuation valve units, in order to assure a constant air/water-ratio independent from the filling level in the emergency storage room.
5.2.3
Domestic connection chambers
It has proved practical to provide each house with its own connection for reasons of liability. It is fundamentally possible, under certain conditions, to lead several residential units (for ex. with row houses) to one domestic connection. Houses with several stories are normally drained via one domestic connection. In this case the requirements defined in section 5.2.2 are valid. Normally domestic connection chambers are installed at the premises offering thus the advantage of a short gravity line which is quite advantageous in case of a deep level pipeline. Devices for function monitoring for ex. local signalising or remote/tele-transmission of an eventual backflow and/or continuously open evacuation valve might be useful according to certain circumstances. Domestic connection chambers must be secured against floating in case of necessity.
5.2.4
Collection chambers
For the domestic installation pay attention to the backflow level which is in general defined by the shaft covering. Collection room have to be easily accessible in order to facilitate the removal of rough particles. It must be possible to clean and suck off those rooms eluding the evacuation valve. In case evacuation valve units are positioned where they can be flooded by wastewater work hygienic requirements have to be taken into account. All connecting elements and accessories in the domestic connection chambers have to consist of non-corrosive material (for ex. synthetic material or of non-corrosive steel according to DIN EN 10088).
5.2.5
Evacuation valve
On opening evacuation valves have to offer a completely free passage of at least 40 mm. Evacuation valve units must be made of appropriate resistant material. As for elastomere see DIN EN 681-1.
5.2.6
Level indicator
Level indicator pipes have to be positioned in a way that they are cleansed by streaming during the evacuation process. Floating switches are not appropriate due to their contamination sensitivity.
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ATV-DVWK-A 116, Part 1________________________ 5.2.7
Valve control
The evacuation valve may only be opened by the control unit if the occurring vacuum pressure is at least at 15 kPa (0,15 bar). In case collection rooms with a chamber bottom of more than 1,0 m beneath the evacuation valve are sucked off, the control unit is to open the evacuation valve only in case of relevant stronger under pressure. The valve control must keep the air/water-ratio roughly independent from the occurring vacuum pressure.
5.2.8
Explosion proof (collection chamber)
All electrical installations inside collection chambers have to be built in explosion-proof design.
5.2.9
Endurance life of membranes and seals
See DIN EN 1091.
5.2.10
Components of vacuum pressure lines
Vacuum lines must be resistant against: •
Chemical and biochemical influences from inside and outside
•
Temperatures up to 35° C
•
Mechanical abrasion
•
Pressure from in- and outside (according to DIN EN 1401)
Please pay attention also to special stress factors.
5.2.11
Pipeline dimensions
The minimum nominal width of vacuum conduits is DN/ID 65, since – due to federal statutes - in Germany the inlet of coarse particles into the sewer network is forbidden.
5.2.12
Domestic connection lines
Domestic connection lines must be lockable manually in order to facilitate maintenance and replacement works of the relevant evacuation valves without occurring under pressure. They have to be inserted into vacuum pressure conduits with a an angle of at the most 55° in the direction of flow (see figure 2).
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ATV-DVWK-A 116, Part 1________________________
(calculated result)
Slope > 0.2% (vertical) Slope > 0.2%
(horizontal)
Figure 2:
Connection of a domestic connection line
5.2.13
Connection of subsidiary pipelines (ramification of vacuum pressure conduits)
Subsidiary pipelines have to be inserted into vacuum pressure conduits with a an angle of at the most 45° in the direction of flow (see figure 3). Before connecting them the lowest points of the peaks in main and subsidiary pipelines must be at a higher level than the crown height of the lowest point after connection in order to prevent a back flowing of wastewater.
Slope > 0.2%
Slope > 0.2%
Junction with 45°
Figure 3:
Connection of a branch line
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ATV-DVWK-A 116, Part 1________________________ 5.2.14
Cut-off devices
Cut-off devices must be corrosion-proof, corrosion-protected and plug-free. Normally stop slide valves in an enamelled box without slot with rubber wedge are used. Extension spindles must be made of stainless steel. Inspection pipes are to be placed at maximum intervals of 100 m in front and behind of each cut-off device in order to have an opportunity for cut-off and monitoring as well as for an exact leak detection - by means of cut-off bubbles. The location of cut-off devices and inspection pipes have to be marked by signs which have to be included in the municipal canal registering. The y must be solidly secured by closure caps according to DIN 4055 resp. DIN 4056, marked by the sign “A”.
5.2.15
Vacuum tanks
Vacuum reservoirs can be buried into the soil or installed inside a vacuum station. If necessary they must be secured against floating and resist to a vacuum pressure of 90 kPa. Steel vessels have to be coated from in- and outside with appropriate coating materials. In case of several vacuum pressure vessels the incoming vacuum conduits must be connected to each other in such a way by means of sliders and cross-links that a correct operation is secured also in case of failure of one tank. If there is only one tank available possibilities for its substitution have to be taken into account.
5.2.16
Control of the vacuum station
Failures and intermittences must be signalised even in case of power failure. Fault messages are crucial also in cases of: failure of a discharge pump, vacuum pump, exceeded running time of discharge or vacuum pumps, short-fall of minimum vacuum pressure as well as exceeding maximum filling level.
5.2.17
Filling level supervision
Vacuum reservoirs may only be filled up to the half by wastewater. In case the maximum filling level is exceeded the vacuum pumps have to switch-off automatically.
5.2.18
Equipment / vacuum pump
For safe operation of the system the ambient temperature in the vacuum station has to be maintained between +1 °C and +35°C. Appropriate insulation, ventilation and heating are to be taken into account.
5.2.19
Operational capacity of onward conveyance facilities
At least two devices of the same operational capacity must be available for the onward conveyance of wastewater away from the vacuum reservoirs, one of them as redundancy.
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ATV-DVWK-A 116, Part 1________________________ 5.2.20
Construction of feeding pumps
Submersible or dry-mounted pumps can be installed. The diameter of free passage must correspond at least to the free passage of the largest suction pipe before the evacuation valves, unless pumps with cutting facilities are installed. It must be assured that in the pumps a formation of gas is excluded.
5.2.21
Exchange of feeding pumps
See DIN EN 1091.
5.2.22
Explosion-Proof (Vacuum Station)
The electrical equipment in vacuum reservoir and in the suction lines must be explosionproof. Flame traps and detonation safety devices between vacuum reservoirs and vacuum pumps are not requested, particularly as they tend to obstruction/occlusions. In case vacuum pumps which might be ignition sources are used please assure facilities for sweeping with inert gas (e.g. Carbon dioxide). After being in operation for more than 48 hours, before re-operation, a sweeping with inert gas of the vacuum pumps has to be executed. The procedure has to be described in the manual.
5.2.23
Non-return valves
See DIN EN 1091.
5.2.24
Propulsion jet ejectors
The diameter of free passage must correspond at least to the free passage of the largest suction pipe before the evacuation valves, unless pumps with cutting facilities are installed.
5.2.25
Odour reduction
The ventilation pipelines are to be so laid that possible odour nuisance in the neighbourhood is to be avoided with certainty, with heavier intromission of odours an odour reduction, e.g. through compost filter plants (biofilter), is to be undertaken. Percolating water out of compost filter plants is contaminated organically and has to be discharged together with the wastewater.
5.2.26
Noise reduction
The regulations of TA-Noise have to be observed. The maximum permitted night noise intromission value according to TA-Noise is currently: • • • • •
For purely residential areas For general residential areas For mixed areas For commercial areas For industrial areas
35 dB (A) 40 dB (A) 45 dB (A) 50 dB (A) 70 dB (A)
Insofar as no area identification is available it is to be based on actual usage.
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ATV-DVWK-A 116, Part 1________________________ 5.2.27
Emergency power supply
See DIN EN 1091.
5.3.
Requirements for the planning
5.3.0
General
The planning of discharge/drainage systems is subject to DIN EN 752-3. The draft resulting of engineering planning and calculations should contain the following parts: • • • • • • • • •
Legend report with general location plan Entire location plan of the vacuum drainage network Longitudinal section of the vacuum drainage network Hydro-pneumatic dimensioning/design Dimensioning of the vacuum station System plan of the vacuum station Computation of quantities and cost calculations Comparison of costs tableau Estate plan
5.3.1
Dimensioning of pipelines
The graduation of the nominal width of vacuum conduits results from the hydro-pneumatic layout. Vacuum lines made of PVC must meet the standards of SDR-class 21. As for PVC-U (Pipes made from unplasticised Polyvinyl Chloride) the standards of DIN 8061, DIN 8062, DIN 19532 and the Work Sheet W 320 of DVGW is to be applicable. The thermal expansion coefficient of 0,08 mm/(m.K) has to be taken into consideration. Adhesive and plug-in sleeves with seals made from elastomers compatible to vacuum pressure according to DIN 4060 can be used. Particular care has to be taken as for adhesive connections which can be done only after having cleansed the adherends carefully and in accordance with the processing manual of the manufacturer. Vacuum lines made of PE (Polyethylene) must meet the standards of SDR-class 11. As for PE-HD (Pipes made from High Density Polyethylene) the standards of DIN 8074, DIN 8075, DIN EN 12201 as well as the Work Sheet W 320 of DVGW is to be applicable. The thermal expansion coefficient of 0,20 mm/(m.K) has to be taken into consideration. Plug-in sleeves with seals made from elastomers compatible to vacuum pressure according to DIN 4060 or weld joints can be used. Particular care has to be taken as for weld joints and can only be done by specialised staff. Varying from DIN EN 1091 all pipes and fittings in vacuum lines must have a nominal pressure of at least 1,0 MPa (10 bar) according to DIN EN 1333.
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ATV-DVWK-A 116, Part 1________________________ 5.3.2
Height profiles of the lines
The height profile of vacuum lines must be so done that wastewater occurs at the lowest points which is then accelerated by the re-flowing air and pushed onto subsequent peaks. Substantially three types of height profiles are known: (see figure 4): • • •
Wave Profiles, to be done without fittings and without bending the lines Saw Tooth Profiles with 45°-fittings, preferably to be used with nominal widths with more than DN 100 Reformer Pocket Profiles similar to saw tooth profiles – with the difference that in front of the 45°-slopes additional U-formed depressions are fixed. Reformer Pocket Profiles are preferably used with nominal widths up to DN 100.
The height profile as well as the dimensioning has to be coordinated in collaboration with the manufacturer of the system.
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ATV-DVWK-A 116, Part 1________________________ Wave Profile
(W) Inspection Pipe
Inspection Pipe
min. 0.2 % Slope
Profile Dimensions:
Saw Tooth Profile
(S)
Inspection Pipe
Inspection Pipe
min. 0.2 % Slope Profile Dimensions:
Reformer Pocket Profile
(R)
Inspection Pipe
Inspection Pipe
min. 0.2 % Slope Profile Dimensions: H > di + 5 cm; h = H; L < 500 · H
Figure 4:
Height profile examples with flat terrain
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ATV-DVWK-A 116, Part 1________________________ 5.3.3
Hydro-pneumatic layout
The maximum static pressure height difference is calculated under the condition that all slopes are filled with water. The maximum static pressure height difference of a slope is the height H (height difference between deepest point and subsequent peak), reduced by the pipeline internal diameter d. The sum of maximum static pressure height differences along the trunks may not as a rule exceed the value of 4 till 5 m. Larger pressure height differences request the installation of automatic ventilation valves which regulate an automatic inlet of air into the vacuum lines in case a prefixed value of vacuum pressure is not reached – preventing thus that all slopes are at the same time filled with water. Unfortunately an exact hydro-dynamic calculation of the conveyance processing inside vacuum lines is impossible due to complex, unsteady and poly-phased flow conditions. Therefore, for lack of theoretical basic factors for pipeline-network-dimensioning a lump-sum calculation with standard values which are valid for the mentioned height profiles. The average air/water-ratio of a main trunk is estimated by means of the standard values mentioned in tableau 1. Tableau 1: Standard values for estimating the average air/water-ratio of the main trunk Trunk length
Factor f with inhabitant/m network length
of the main line
0,05 E/m
0,1 E/m
0,2 E/m
0,5 E/m
average air/water-ratio 3,5 – 7 3-6 2,5 – 5 4–8 3,5 - 7 3–6 5–9 4-8 3,5 – 7 6 – 10 5-9 4–8 7 – 12 6 - 10 5–9 8 – 15 7 - 12 6 – 10 * recommended only for special exceptional cases 500 m 1000 m 1500 m 3000 m 4000 m
2–5 2,5 – 5 3-6 3,5 - 7 4-8 (5 – 9)*
By means of the standard values from the tableau 2, the nominal widths graduation of a trunk is calculated considering the upstream number of the connected inhabitants as well as the medium upstream air-water-ratio. Please pay attention to the fact that the medium upstream air-water-ratio at the ends of the trunks exceeds the average value (to be calculated according to tableau 1) and descends in the direction of the vacuum station up to the average value. Most of the projects suitable for vacuum discharge can be dimensioned by means of the afore-mentioned standard/approximate values. They refer to a discharge/flow value of 0,005 l/(s.E), to an even/constant allotment/arrangement of the connections on plain grounds. It is clear that projects based on special conditions cannot be calculated with lump-sumcalculations as mentioned before. It is recommended to revert to the firm who offers the system. In case of divergences from the lump-sum-calculation technical reasons have to be explained. Particularly the operational security can be assured by means of additional technical measures such as ventilation facilities or evacuation valve units with intermittent water- and air-inlets.
20
April 2004
ATV-DVWK-A 116, Part 1________________________ The detailed calculation is based on the pressure-profiles in idle state, in case of peak passage and the pulsatory flowing occurring at the ends of the trunks - depending on the air/water-ratio. Tableau 2: Standard value for estimation of nominal widths Medium airwater-ratio upstream
Nominal width of the trunk DN 65
DN 80
DN 100
DN 125
DN 150
DN 200
DN 250*
Number of inhabitants connected upstream 2
0-110
0-350
250-600
350-900
500-1400
750-2100 (1100-3000)
4
0-65
0-200
135-340
200-500
300-800
400-1200 (600-1650)
6
0-45
0-140
95-240
140-350
200-550
300-820
(400-1150)
8
0-35
0-105
75-185
105-270
150-425
220-625
(300-850)
10
0-30
0-85
60-150
85-220
120-340
175-500
(250-700)
12
0-25
0-75
50-125
75-180
100-290
150-425
(200-600)
* recommended only for special exceptional cases
5.3.4
Basic Values for the dimensioning
Normally a rated wastewater-discharge of 0,005 l/(s.E) is supposed. The quantity of arising wastewater from commerce and industry has to be converted into an equivalent per inhabitant and discharge whereas one equivalent per inhabitant and discharge corresponds to the occurring quantity of 150 l/d. In special cases the rated wastewater-discharge has to be calculated and divided into 0,005 l/s. External water quantities do not have to be taken into account additionally, besides in case of leaky gravity lines of the houses connected at the level of ground water.
5.3.5
Vacuum Station
The maximum air passage value QL (in standard conditions) is calculated by multiplying the rated discharge value QS by the medium air/water-ratio. For the dimensioning of vacuum pumps QL is multiplied by the security value SF between 1,2 and 1,5. Conveying streams and number of single waste water pumps (QS,p and ns) as well as the individual vacuum pumps (QL,p and nL) have to be chosen considering one redundancy aggregate each – which means as follows: QS,p ≥ QS / (ns – 1)
(l/s)
(1)
(l/s)
(2)
and QL,p ≥ QL . SF / (nL – 1)
21
April 2004
ATV-DVWK-A 116, Part 1________________________
The suction volume per each vacuum pumps is herewith as follows: QL,p,s ≥ QL,p . pu . 2 / (pmax + pmin) (l/s)
(2a)
Herewith the ambient pressure is pu and pmax as well as pmin are the maximum and minimum absolute pressure inside the vacuum reservoir. The minimum volume of the vacuum reservoir is calculated under consideration of the maximum switch-on-frequency of the aggregates of 12/h. Thus the minimum volume of water requested VW is: VW
=
0,25 . QS,p / f
(l)
(3)
The minimum air volume requested is: VL = 0,25 . QL,p,s . 1/2 . (pmax + pmin) / [(pmax + pmin) . nL . f ]
(l)
(4)
With an increasing number of vacuum pumps nL consequently the volume requested is lower. The total number of vacuum producing pumps nL may only be inserted into the beforementioned equation/evaluation provided that all vacuum pumps are switched-on in turn one by one. The calculated air volume VL may be reduced by part of the quantity of volume in the incoming lines VS. With this at the most half of the pipeline volume in a specific section parting from the vacuum station where the total sum of the maximum hydrostatic pressure differences is lower than Pmax – Pmin. has to be taken into thorough consideration. Example: the number of switching operations Pmax – Pmin = 10 kPa and directly in front of the vacuum reservoir a height skip of maximum hydrostatic height difference of more than one meter is fixed, no pipeline volume can be taken into account. The requested tank volume is: V = Vw + VL – VS
(l)
(5)
(l)
(6)
The minimum volume of the vacuum reservoir is: V ≥ 3 . Vw
Die power intake/consumption of the vacuum pumps as well as the wastewater discharge pumps can be estimated as follows: PL,P = {К / ( К- 1) } . QL,P,S {( К-1)/ К}
PS,P = QS,p
.
.
½ . (Pmax – Pmin )
.
[ 1 – (½ . (Pmax – Pmin ) / Pu)
] / ηL
(7)
p . g . hman / ηW
(W)
(8)
As for air the adiabatic coefficient К = 1,4. The efficiency of water ring pumps and sliding vane rotary pumps is between 0,3 < ηL < 0,6 (for Pmin ≥ 30 kPa), whereas sliding vane rotary pumps offer a higher efficiency than water ring pumps. The efficiency level when combining propulsion jet ejectors with rotary pumps is
22
April 2004
ATV-DVWK-A 116, Part 1________________________ very low, and lies between 0,05 < ηL < 0,1. The efficiency of wastewater-rotary pumps lies between 0,2 < ηw < 0,5.
5.3.6
Sources of additional information
Kindly refer to the working reports mentioned in appendix G of the ATV-DVWK-working group ES-1.2 as well as the material of the bibliography/literature list.
5.3.7
Application fields for vacuum discharge systems
See section 4.0 as well as Appendix l of DIN EN 1091.
6
Laying of pipelines
6.1
Laying of pipelines
It is recommended that at the beginning of the construction works the manufacturer of the system introduces the employees of the relevant construction firm concerning laying of pipelines and installation of the domestic connection chambers. Vacuum pipelines are to be laid exactly in accordance with the implementation plans. The location of the high and low points must be durably safeguarded in order to maintain the functional capability of the system and must be authorized by the planner. Before backfilling the respective location the planner as well as the ordering firm must check the height profile of the already laid vacuum lines. As far as local regulations do not contrary, vacuum lines and potable water lines can be laid in a common trench because wastewater cannot leak out of vacuum lines. Pipelines are to be laid frost-free and have to firmly withstand traffic and earth loads, lifting and impact forces as well as vacuum pressure during operation and tightness checks. If required, over-ground pipelines sections have to be protected against extreme temperature effects, UV rays as well as mechanical damages. Pipelines made from PVC are only to be laid at a temperature of at least 4°C. Please avoid extreme tension during shrinking when chilling happens in case of PE-pipelines. The location of the high and low points must be durably safeguarded. This safeguarding is particularly important in soft ground (e.g. bog, clay) as otherwise the system can fail. DIN EN 1610 and ATV-DVWK-A 139 is relevant as for the laying, in particular for the forming of the pipe bed. High and low points can, in the case that the manufacturer of the vacuum system does not lay down anything else, be formed by bending the pipes. The permissible minimum bending radii according to DVGW (German Association of Gas and Water Engineers) G 472 are to be observed – they are: for pipes made from PVC-U R > 300 . da and for pipes made from PEHD R > 50 . da - please pay also attention to the manual edited by the manufacturer. Pipeline joints are to be done in accordance with the instructions laid down from the manufacturer. The fittings (branches) for the domestic connections are installed on laying the collection mains. With this it is recommended taking appropriate note of open building sites in order to avoid a later more expensive installation.
23
April 2004
ATV-DVWK-A 116, Part 1________________________ Under certain circumstances a laying without trenches/ditches according to DIN EN 12889, for ex. by flush boring, ploughing and milling may be taken into account. With this it must be safeguarded that divergences from the height profile do not arise. For information please turn to the manufacturer of the system. A master plan is to be produced according to DIN 2425-4 after laying of the pipes.
6.2
Tolerances
In case the descending gradient of the pipelines exceeds 1:150 the level of the high and low points may not deviate more than ± 2,5 cm from the height profile fixed – ascending and descending gradients in between must be stable.
6.3
Warning and detecting facilities
See DIN EN 1091.
7
Checks and testing
As for the testing of evacuation/suction valve units, pipelines and domestic connection chambers, the Appendixes A - C of DIN EN 1091 have to be observed. Tightness tests according to sections 7.2. and 7.3 of DIN EN 1091 are to be done before the installation of the evacuation valve units. Approval tests according to section 7.4 have to be described thoroughly concerning type and size in the tender/bid – whereas the execution is subject to Appendix D or DIN EN 1091.
8
Commissioning (Acceptance)
The manufacturer of the system should optimise the operation during commissioning and train the relevant staff accordingly.
9
Economical aspects
Investment costs as well as operational costs should also be included into cost comparison calculations. The total amount of costs of a vacuum discharge system might be considerably lower in comparison with conventional systems. Please turn to the service life data shown in Appendix M as well (see also Working Report from 1997 mentioned in Appendix G).
Appendixes A till E: See DIN EN 1091.
24
April 2004
ATV-DVWK-A 116, Part 1________________________ Appendix F:
Hints on operation and maintenance
Supplementary to Appendix F of DIN EN 1091 applies the following: •
To keep an operating logbook
•
To conclude a maintenance contract with the deliverer of the system
•
Operating firms should keep some suction valve units in stock for renewal and eventual exchange
•
In order to keep service frequency low as well as to safe time needed for detecting the defects, a preventive maintenance is recommended according to the manufacturer
•
Local and federal regulations and instructions of self-regulating and self-control decree have to be observed
Appendix G:
Sources of additional information
ATV-A 200
Basic standards for wastewater discharge in rural areas
ATV-DVWK-A 139
Installation and testing of wastewater lines and conduits
ATV-DVWK-A 142
Wastewater lines and conduits in water procurements areas
DIN 1960
VOB Rules and regulations concerning placement of orders in the construction business
DIN 1986
Discharge plants for buildings and real estates
DIN 2425-4
Plans of the supplying industry, water economy and for longdistance Lines – Part 4: pipeline network plans of public wastewater lines
DIN 4055
Water lines; Street cap for underfloor hydrants; technical rule of DVGW
DIN 4056
Water lines; Street cap for cut-off fittings; technical rule of DVGW
DIN 4060
Pipeline connections of wastewater conduits and lines with seals made of elastomer – requirements and tests at pipeline connections containing elastomer-seals
DIN 8061
Pipes made from unplasticised Polyvinyl Chloride – General Quality Requirements, Testing
DIN 8062
Pipes made from unplasticised Polyvinyl Chloride (PVC-U, PVC-HI) Dimensions
DIN 8074
Pipes made from High Density Polyethylene (PE) – PE 63, PE
25
April 2004
ATV-DVWK-A 116, Part 1________________________ 80, PE 100, PE-HD – Dimensions DIN 8075
Pipes made from High Density Polyethylene (PE) – PE 63, PE 80, PE 100, PE-HD – General Quality Requirements, Testing
DIN EN 681
Elastomer – Seals – Material requirements for seals for pipelines for the use in water supply economy and discharge economy
DIN EN 752-3
Discharge systems outside of buildings – Part 3: Planning
DIN EN 1085
Dictionary for the wastewater treatment
DIN EN 1091
Vacuum discharge systems outside of buildings
DIN EN 1333
Pipeline components – Definition and selection of PN
DIN EN 1401
Unplasticised Polyvinyl Chloride (PVC-U) – requirements on pipes, fittings and pipeline network
DIN EN 1610
Laying and testing of wastewater line and conduits
DIN EN 1671
Pressure discharge systems outside of buildings
DIN EN 10088
Stainless steels
DIN EN 12056
Gravity discharge plants inside of buildings
DIN EN 12889
Ditchless laying and testing of wastewater lines and conduits
DIN EN 12201
Plastic-pipeline systems for the water supply – Polyethylene (PE)
Part 1: Part 2: Part 3: Part 5:
General Pipes Fittings Performance capability
DVGW-W 320
DVGW = German Association of Gas and Water Engineers, Production, Quality Assurance and Testing of Pipes made from PVC rigid, HD-PE rigid and LD-PE for Water Supply and Requirements for Pipe Connections and Pipeline Components
RAL-GZ 961
Production and maintenance of wastewater lines and conduits Quality Assurance
TA-Lärm
Technical Manual Noise
Working report
of the ATV (Association for wastewater technology) - DVWK (German Association of Gas and Water Engineers) - working group ES 1.2 Special discharge procedures „Questions on operation and service life of vacuum and pressure drainage systems”, Korrespondenz Abwasser 44 (1997) H. 5, Page 921 ff.
26
April 2004
ATV-DVWK-A 116, Part 1________________________ Working report
of the ATV (Association for wastewater technology) - DVWK (German Association of Gas and Water Engineers) - working group ES 1.2 Special discharge procedures „Comparison of the Worksheet ATV-A 116 with the European Standards DIN EN 1091 (vacuum discharge/drainage) and IDN EN 1671 (pressure discharge/drainage)”, Korrespondenz Abwasser 47 (2000) H. 2, Page 258 ff.
Appendix H:
Literature / Bibliography
1. Liernur “Die pneumatische Canalisation in der Praxis”, Verlag der Ingenieur-Firma Liernur & De Bruyn-Kops, Frankfurt am Main (1873) 2. Foreman B:E. “Wastewater Collection by Vacuum”, Proceedings of the International Symposium on Urban Hydrology, Kentucky, USA (1985), S. 37 ff. 3. Kleinschroth A. “Abfallstoffe und ihre Beseitigung – Auszüge aus einer Veröffentlichung des Oberingenieurs Adam Kleinschroth aus dem jahre 1909”, Informationsberichte des Bayerischen Landesamtes für Wasserwirtschaft, München (1986) H. 3, S. 193 ff. 4. Dippold W. und Jedlitschka J. „Vakuumsystem und Druckentwässerung – Bericht über die Abwasserbeseitigung der Donaugemeinden Fristingen und Kicklingen, Landkreis Dillingen/Donau“, Wasser und Boden 28 (1976) H. 5, S. 100 ff. 5. Drebes H. und Ivers H. „Vakuumentwässerung Krempel/Dithmarschen“, Wasser und Boden 27 (1975) H. 5, S. 115 ff. 6. Horwitz S. „Abwasserförderung mit Vakuum – eine volkswirtschaftlich günstige Lösung der kommunalen Abwasserprobleme“, Wasser und Boden 23 (1971) H. 10, S. 291 ff. 7. Winkelmair G. „Abwasserableitung in gefällelosen Leitungen kleinen Durchmesser – Das Vakuumsystem“, Wasser und Boden 26 (1974) H. 8, S. 229 ff. 8. ATV-Handbuch „Bau und Betrieb der Kanalisation“, 4. Auflage (1995), Verlag Ernst & Sohn, Berlin. S. 387 ff. 9. Roediger M. „Unterdruck- und Druckentwässerung – alternative Verfahren der Ortsentwässerung“, Abwassertechnik (1995) H. 6, S. 11 10. Pfeiffer W., Roediger M. „Anforderungen an die Kanalisation bei Druck- und Unterdruckentwässerung“, Schriftenreihe WAR der TH Darmstadt, Band 82 (1995) S. 211 ff. 11. Roediger M., Schütte M. „Besondere Entwässerungsverfahren Betriebserfahrungen“, Korrespondenz Abwasser 39 (1992) H. 6, S. 865
–
12. Goldberg B. „Unterdruckentwässerung – ein sicheres Verfahren für verträgliche Abwassergebühren“, WWT (1995) H. 5, S. 20 13. Anonym „Vakuumentwässerungstechnologie erstmalig erfolgreich im Bereich der Chemieindustrie eingesetzt“, Umwelt (1995) H. 7-8, S. 284
27
April 2004
ATV-DVWK-A 116, Part 1________________________ 14. Jedlitschka J. „Druck- und Unterdruckentwässerung“ Berichte der ATV H. 37, St. Augustin (1986) S. 133 ff. 15. LAWA (Länderarbeitsgemeinschaft Wasser) „Leitlinien zur Durchführung von Kostenvergleichsrechnungen“ (1998) 16. Schluff R. „Unterdruckentwässerung – Neue Erkenntnisse führen zu einem betriebssicheren Fördersystem“, Abwassertechnik 37 (1986) H. 4, S. 37 ff. 17. Schluff R. „Unterdruckentwässerung – Abwasserbeseitigung im ländlichen Raum“, Eigenverlag, Heikendorf (1991) 18. Schrieber R. „Vakuum-Kanalisation“ – Neue Wege führen Betriebssicherheit“, Abwassertechnik 40 (1989) H. 2, S. 43 ff.
zu
erhöhter
19. Schinke R. „Die Vakuumkanalisation – ein Verfahren mit vielen, oft ungenutzten Möglichkeiten“, Korrespondenz Abwasser 46 (1999) H. 4, S. 506 ff. 20. Otterpohl R. u.a. „Alternatiave Entwässerungskonzepte zum Stoffstrommanagement“, Korrespondenz Abwasser 46 (1999) H. 2, S. 204 ff. 21. Hassett A.F. und Starness J.C. „Vacuum Wastewater Collection: The Alternative Selected in Queen Ann’s County, Maryland”, Jl. Water Poll. Control 53 (1981) H. 1, S. 59 ff. 22. Hassett A.F. und Starness J.C. “Old Vacuum Sewer Reaches New Heights”, Proceedings of the Water Environment Federation, 65th Annual Conf. New Orleans (1992) 23. Hassett A.F. “Vacuum Sewers – An Uplifting Global Future”, Proceedings of the New and Emerging Environmental Technologies and Products Conference for Wastewater Treatment and Stormwater Collection, Toronto Canada (1995) 24. Averill D.W. und Heinke G.W. “Vacuum Sewer Systems”, Report prepared for Northern Science Research Group of the Canadian Department of Indian Affaires and Northern Development (1974) 25. “Alternative Sewer Systems”, Manual of Practice, Water Environment Federation, Alexandria, Virginia (1986) 26. “Alternative Wastewater Collection Systems”, Manual, Environmental Protection Agency, Washington, DC (1991) 27. ATV-Arbeitsgruppe 1.1.2; Arbeitsbericht Abwassertransportleitungen – Planungs-, Bau- und Korrespondenz Abwasser 34 (1987), Heft 1, S. 70-76
28
“Druckluftgespülte Betriebsgrundsätze”;
April 2004
ATV-DVWK-A 116, Part 1________________________ Appendix I:
Use of vacuum drainage systems
See Section 4.0.
Appendix K:
Calculation example
K. 1 Data A locality with 910 inhabitants is to be connected via a vacuum drainage system to a sewage treatment plant (figure K. 1). The terrain is completely flat. There are two main trunks. For the sake of illustration both trunks are very different which is normally quite improbable.
Vacuum Station VS
Figure K.1:
Calculation example of a vacuum drainage system
For the trunk (1) up to (U) a wave profile with pipelines made from PE-HD are chosen whereas for the other trunk (A) up to (U) pipelines made from PVC and a combination of saw tooth profile and pocket reformer profile are applied. The following height profiles serve as example only. It is also possible - if agreed upon with the manufacturer of the system - to arrange them in a different way.
29
April 2004
ATV-DVWK-A 116, Part 1________________________ K. 2 Pipeline network dimensioning Upper and lower network parts are investigated separately. Trunk (1) till (U) – wave profile: Trunk length: Number of inhabitants: Population density: Medium air/water-ratio according to table 1: Intervals of inspection pipes: Location of the inspection pipes:
1900 m 130 E 0,07 E/m LWV = 6 till 9 max. 100 m wave profile at random
Height difference between highest and lowest points:
H ≈ dl + 5 cm
Maximum hydrostatic pressure height difference in each ascending section:
h = H - dl ≈ 5 cm
Bending radius for PE-HD:
R ≥ 50 . da
Length of ascending sections:
Ll ≥ 2 . (R.H)1/2
Inclination of descending sections:
≥ 0,2 %
Length of descending sections:
L2 ≤ 500 . H
Out of the table 1 (by interpolation) results a medium air/water-ratio between 5,4 and 9,4. Due to the uneven distribution/arrangement of domestic connections (only 30 E are at an interval of < 900 m, 100 E > 900 m) out of these numbers a value of at least 8 is chosen. At the end of the trunk a local air/water-ratio at the domestic connections between 12 and in proximity to the vacuum station of 4 is adjusted, in order to reach in the trunk a medium air/water-ratio of at least 8. The system is subdivided into single sections. For each section the upstream inhabitant values connected are accumulated to Σ EWi. The medium LWV at the end of the section is calculated as Σ (EWi . LWVi) / Σ EWi. The nominal width DN of the section are taken from table 2. The distances Li between the low points depend on the internal diameter di (see tableK.1). Therewith the sum of ni of the low points is ni = Li / li
30
April 2004
ATV-DVWK-A 116, Part 1________________________ Table K.1: Example for a height profile in flat terrain with PE-HD pipelines in wave profile External diameter da of PE-HD pipes (mm)
Internal diameter of SDR 11 pipes (mm)
75 90 110 125 140 160 180 200 225 250 280
61 74 90 102 114 131 147 164 184 204 229
Chosen height difference H between high and low points (cm) 10 12 14 15 16 18 20 22 24 26 28
Minimum L1 of increasing sections (rounded) (m)
Maximum L2 of descending sections (m)
1,25 1,5 1,75 2 2,1 2,4 2,7 3 3,3 3,6 4
50 60 70 75 80 90 100 110 120 130 140
Chosen difference L of low points from each other (m) 50 60 70 75 80 90 100 110 120 130 140
Since - with wave profile and flat terrain - each ascending section has a maximum static pressure height difference of approx. 5 cm, the results are a maximum static pressure height difference of the sections as follows: hi = ni . 5 cm = Li / li . 5 cm. With ascending terrain the lengths Li would be shorter and/or the height differences H would be bigger. This would result in more low points and/or larger pressure height differences hi. In case of descending terrain the situation would be the opposite. In order to have an approximate result the geodetic height differences can be added to the sum of the maximum hydrostatic pressure height differences. The pressure height differences are added up to Σ hi , whereas hi is added up to the highest value of the pressure height at the beginning of the section. The total maximum hydrostatic pressure height difference of the main trunk along the length 1-2-3-4-U (as mentioned in the example) is only 1,55 m WS or 15,2 kPa. The maximum hydrodynamic pressure loss however, will surely be greater.
31
April 2004
ATV-DVWK-A 116, Part 1________________________ Table K.2: Calculation of trunk (1) till (V) 1
2
3
4
5
6
7
8
9
Section
PE at Section
Total PE till senction end
Local LWV at section end
Medium LWV at section end
Nominal width section accord. tableau 2
Section length
Distanc e of low points from each other
Number of low points in section
10 Max. stat. press. height diff. in section
11
i
EWi
Σ EWi
LWVi
Σ (EWi LWV1) / Σ EWi
DNi
Li
li = f (DNi)
ni = Li /li
hi = ni · 5 cm
1-2 5-2 2-3 6-7 8-7 7-3 3-4 9-4 4-U
15 10 30 10 10 25 0 10 20
15 10 55 10 10 45 100 10 130
12 10 8 10 10 8 6 6 4
12 10 9,5 10 10 8,9 9,2 6 8,2 >8
65 65 80 65 65 80 100 65 100
400 m 150 m 600 m 200 m 150 m 400 m 500 m 200 m 400 m
50 m 50 m 60 m 50 m 50 m 60 m 70 m 50 m 70 m
8 3 10 4 3 7 7 4 6
0,4 0,15 0,5 0,2 0,15 0,35 0,35 0,2 0,3
Max. stat. press. height diff. till section end Σ hi
0,4 0,15 0,9 0,2 0,15 0,55 1,25 0,2 1,55 < 4-5 m
Trunk (A) till (U) in pocket reformer / saw tooth profile: Length of trunk: Number of inhabitants: Population density: Medium air/water-ratio according to table 1: Intervals of inspection pipes: Location of the inspection pipes:
3000 m 780 E 0,26 E/m LWV = 5 till 8 max. 100 m after each high point
Pocket Reformer Profiler (T)
DN 65 and DN 80
Saw Tooth Profile (S)
≥ DN 100
Height difference between highest and lowest points:
H ≥ dl + 5 cm
Maximum hydrostatic pressure height difference at each low point saw tooth profile:
h = H - dl ≥ 5 cm
Inclination of sections:
≥ 0,2 %
Length of sections:
L ≤ 500 * H
32
April 2004
ATV-DVWK-A 116, Part 1________________________ Table K.3:
Calculation example of height profile in flat terrain with pipelines made from PVC in pocket reformer/saw tooth profile
Nominal width of pipe PVC SDR 21
Type of height profile
Height difference H between high and low points (cm)
65 80 100 125 150 200 250
T T S S S S S
20 20 20 20 20 30 30
Max. hydrostatic Distance L height difference at between low points low point (m) (m)
0,2 0,2 0,1 0,075 0,05 0,1 0,05
100 100 100 100 100 150 150
Approx. 400 inhabitants i.e. half of the total number of inhabitants, have a distance of < 1500 m from the vacuum station. Henceforth it is not necessary to increase the LWV value. Section L-E is a special case due to its extremely low population density value of 0,03 E/m. For this section according to table 1 a medium LWV of 6 is chosen. The local LWV lies between 10 at the end of the trunk and 3 in proximity of the vacuum station resulting in a medium value of approx. 6. The maximum hydrostatic pressure height difference of the main trunk along the trunk A B C D E – U is 2,8 m resp. 28 kPa, i.e. no automatic ventilation is requested. Table K.4: Calculation of trunk (a) till (U) 1
2
3
4
5
6
Section
PE at Section
Total PE till section end
Local LWV at section end
Medium LWV at section end
Nominal Section width length section accord. tableau 2
7
i
EWi
Σ EWi
LWVi
Σ (EWi · LWV1) / Σ EWi
DNi
A-B F-B B-C G-C C-D H-D I-D D-E K-E L-E E-U
80 20 70 50 120 40 50 120 100 30 100
80 20 170 50 340 40 50 550 100 30 780
10 90 8 8 6 5 5 4 4 10 3
10 9 9,1 8 7,8 5 5 6,5 4 10 5,9 ≈6
80 65 100 80 150 65 65 200 80 65 200
33
8
9
10
11
Distanc e of low points from each other
Number of low points in section
Max. stat. press. height diff. in section
Li
li = f (DNi)
ni = Li/li
ni · hi acc. tabl K.3
Max. stat. press. height diff. till section end Σ(ni*hi)
500 m 100 m 500 m 300 m 600 m 200 m 300 m 800 m 500 m 1000 m 600 m
100 m 100 m 100 m 100 m 100 m 100 m 100 m 150 m 100 m 100 m 150 m
5 1 5 3 6 2 3 6 5 10 4
1,0 m 0,2 m 0,5 m 0,6 m 0,3 m 0,4 m 0,6 m 0,6 m 1,0 m 2,0 m 0,4 m
1,0 m 0,2 m 1,5 m 0,6 m 1,8 m 0,4 m 0,6 m 2,4 m 1,0 m 2,0 m 2,8 m < 4-5 m
April 2004
ATV-DVWK-A 116, Part 1________________________ K.3
Calculation of Vacuum Station
With specific domestic and industrial wastewater Ws,d of 150 l per inhabitant and day One must be reckoned with a daily wastewater quantity of: Qs,d Qs,d
=
=
Σ (EW) . Ws,d (780 E + 130 E) . 0,15 m3 / (E . d) = 136,5 m3 /d
The following discharge quantities Qs,i in the trunks are basis for assessment: Qs,i Qs,1 Qs,A
= = =
Σ (EW) . 0,005 l/(E.s) 130 E . 0,005 l/(E.s) = 0,65 l/s resp. 780 E . 0,005 l/(E.s) = 3,9 l/s
The total discharge quantities Qs are basis for assessment : Qs Qs
= =
Σ Qs,i 0,65 l/s + 3,9 l/s = 4,6 l/s
The maximum air streams QL in standard conditions of the upper and lower network section are as follows: QL,i QL,1 QL,A
= = =
QS,i . LWVi 0,65 l/s . 8,2 = 5,3 l/s resp. 3,9 l/s . 5,9 = 23 l/s
The total maximum air stream is: QL QL
= =
Σ QL,i 5,3 s + 23 = 28,3 l/s = 102 m3/h
The medium LWV of the entire system is as follows: LWV LWV
=
=
QL / QS 28,3 l/s / 4,6 l/s = 6,2
In case of the following selected values for the switch-on and switch-off pressures of the vacuum pumps: pmin = 35 kPa and Pmax = 45 kPa i.e. a medium pressure value Pmittel of 40 kPa in the vacuum tank, an atmospheric pressure Pu of 100 kPa and a selected security factor SF of 1,25 - the minimum requested suction volume stream QLS of the vacuum pumps is: QL,S SF . QL . Pu / Pmittel = QL,S 1,25 . 102 m3/h . 100 kPa/40 kPa = 319 m3/h = nL = 3 sliding vane rotary pumps with a suction volume QL,P,S of 200 m3/h each (QL,P = 80 m3/h) and nS = 2 wastewater pumps with a passage flow QS,P of 10 l/s each are chosen. That means that the requirements of equation 1 and 2 of section 5.3.5 are met: QS,p ≥ QS / (ns – 1) 10 l/s ≥ 4,6 l/s / (2-1) = 4,6 l/s
(1)
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ATV-DVWK-A 116, Part 1________________________ QL,p,s ≥ QL,S / (nL – 1) 200 m3/h ≥ 319 m3/h / (3-1) = 160 m3/h
(2)
The minimum water volume requested Vw inside the vacuum reservoir/tank as well as the requested air volume VL is as follows (in turn switching of the aggregates and maximum switch-on sequence f of 12/h): Vw Vw VL VL
= = = =
0,25 . 0,25 . 0,25 . 0,25 .
QS,P / f 10 l/s . 3600 s/h / 12 h-1 = 750 l = 0,75 m3 QL,P,S . ½ . (pmax + Pmin)/ [ (pmax + Pmin) ] · f · nL] 200 m3/h · 40 kPa / (10 kPa · 12/h · 3) = 5,6 m3
(3) (4)
The vacuum station disposes of an over ground mounted vacuum tank so that for the incoming trunks height laps of a maximum hydrostatic pressure height difference of more than one meter are planned. That means that the volume in the vacuum line Vs is not taken into consideration. So that the minimum volume V of the vacuum reservoir/tank U is: V = Vw + VL – VS Furthermore the following condition has to be fulfilled :
(5)
V ≥ 3 . VW V ≥ 3 . 0,75 m3 = 2,3 m3
(6)
A tank volume of 7 m3 is chosen. The power consumption/intake per vacuum pump each is approximately as follows: PL,P = {К / ( К- 1) } . QL,P,S {( К-1)/ К}
.
½ . (Pmax – Pmin )
.
[ 1 – (½ . (Pmax – Pmin ) / Pu)
] / ηL
(7)
PL,P = 3,5 . 200 m3/h . 40 kPa [ 1 – (40 kPa / 100 kPa) 0,29] / (360 s/h . 0,4) = 4,5 kW The wastewater is forwarded/pumped via a DN 125 pressure line over the distance of 500 m. The velocity inside the pressure line is approx. 0,8 m/s and the hydraulic pressure height ∆Phydr approx. 30 kPa (0,3 bar). With a vacuum pressure to be overcome of ∆Pvac = Pu – Pmin = 70 kPa and a geodetic height difference ∆Pgeo of 2 m the manometric conveyance pressure ∆Pman is as follows: ∆Pman = ∆Phydr + ∆Pgeo . p . g + ∆Pvac ∆Pman = 30 kPa + 2 m . 1000 kg/m3 . 9,81 m/s2 + 70 kPa = 120 kPa = 1,2 bar The consumption intake of the wastewater pump is approx.: PS,p PS,p
= QS,P . ∆Pman / nS = 0,01 m3 /s . 120 kPa / 0,48 = 2,5 kW
(8)
The medium daily running time ts (d) of the wastewater pumps is: ts (d) = QS,d / QS,p ts (d) = 136,5 m3/d / (0,01 m3/s . 3600 s/h) = 3,8 h/d The total medium daily running time of the vacuum pumps is: TL (d) = QS,d . LWV/QL,p TL (d) = 136,5 m3/d . 6,2 / 80 m3/h = 10,6 h/d
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April 2004
ATV-DVWK-A 116, Part 1________________________ That means that the daily electrical current consumption will be as follows: W(d) W(d)
= PS,P . Ts (d) + PL,P . tL (d) = 2,5 kW . 3,8 h/d + 4,5 kW . 10,6 h/d = 57 kWh/d
Or expressed differently as for the volume: W(V) = W(d) / QS,d W(V) = 57 kWh/d / 136,5 m3/d = 0,42 kWh/m3 Or: per inhabitant value and year: W(EW) = W(V) . WS,d . 365 d/a W(EW)= 0,42 kWh/m3 . 0,15 m3/(E.d) . 365 d/a = 23 kWh/(E.a)
Apppendix L:
Explanation of symbols
da
(mm)
external diameter of a pipeline
di
(mm)
internal diameter of a pipeline
DN
(mm)
nominal diameter
EDL
(E/m)
longitudinal inhabitant density
EW
(E)
inhabitant value (sum of number of inhabitants and inhabitant equivalents)
EWi
(E)
inhabitant value connected to section of pipelines i
f
(1/h)
maximum switch-on frequency of electric motors
g
(m/s2)
acceleration due to gravity
H
(m)
Height of a slope in an vacuum line = Height difference between the deepest point and subsequent peak
h
(m)
maximum pressure head of a slope
hi
(m)
maximum pressure head in section i of the pipeline
hman
(m)
manometric delivery head
Li
(m)
length of the pipeline section i
li
(m)
interval of the low points in pipeline section i
LWV
(-)
air/water-ratio (air volume in standard conditions)
LWV1 (-)
local air/water-ratio of the domestic connection in pipeline section i
ni
total number of low points in pipeline section i
(-)
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April 2004
ATV-DVWK-A 116, Part 1________________________ nL
(-)
total number of vacuum producing pumps
nS
(-)
total number of wastewater pumps
Pmax
(kPa)
highest absolute pressure inside the vacuum reservoir (switch-on point vacuum pump)
Pmin
(kPa)
minimum absolute pressure inside the vacuum reservoir (switch-off point vacuum pump)
Pmittel
(kPa)
medium absolute pressure inside the vacuum reservoir
Pu
(kPa)
ambient air pressure
PLP
(kW)
performance/power inlet of a vacuum pump
PSP
(kW)
performance/power inlet of a wastewater pump
QL
(m3/h)
airflow at peak discharge at standard conditions
QLS
(m3/h)
airflow at peak discharge at operational conditions
QLP
(m3/h)
airflow of a vacuum producing device at standard conditions
QLPS
(m3/h)
suction volume of a vacuum producing device (vacuum pump)
QS
(l/s)
rating flow/discharge of wastewater
QSd
(m3/d)
medium wastewater discharge per day
QS,p
(l/s)
performance inlet of a wastewater pump
R
(m)
bending radius when laying a pipeline
SF
(-)
safety factor for the dimensioning of vacuum producers
tL(d)
(h/d)
medium daily running time of vacuum pumps
tS(d)
(h/d)
medium daily running time of wastewater pumps
V
(m3)
minimum volume of the vacuum reservoir
VL
(m3)
minimum volume of the vacuum air reservoir
VS
(m3)
air volume to be calculated for the dimensioning of the vacuum reservoir in the incoming collection lines
VW
(m3)
minimum volume in the vacuum reservoir for wastewater
WS,d
(l/(E.d))
medium daily wastewater quantity occurring per inhabitant value
W(d)
(kWh/d)
medium daily electrical current consumption
W(EW) (kWh/(E.a))
medium annual electrical current consumption per inhabitant value
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ATV-DVWK-A 116, Part 1________________________ W(V)
(kWh/m3)
medium electrical current consumption in relation to the wastewater volume
∆Phydr (kPa)
hydraulic pressure height difference
∆hgeo (kPa)
geodetic height difference
∆pman (kPa)
manometric conveyance pressure
∆pvac (kPa)
highest vacuum pressare inside the vacuum reservoir
ŋL
(-)
efficiency of a vacuum pump
ŋS
(-)
efficiency of a wastewater pump
К
(-)
adiabatic exponent of a gas
P
(kg/m3)
water density
Σh1
(m)
maximum hydrostatic height difference up to the end of a pipeline section
Appendix M:
Life cycles
The expected service life of a vacuum pipeline network does not differ from those of conventional drainage (gravity) systems due to the large wall thickness. According to the working report of ATV-DVWK working group 1.1.2 dd. May 1997 (see appendix G) service lives are as follows: • • • • • •
50 till 80 years for the pipeline network 30 till 55 years for domestic connection chambers 30 years for pneumatic suction valve units 25 till 40 years for vacuum tanks 20 years for vacuum pumps and 12 years for wastewater pumps
Appendix N:
Qualification / Training of the staff
Execution of construction work Customers are committed to pay special attention when placing orders for construction and assure themselves of the adequate qualification of the employees of the construction firms. See standards of DIN 1960 (VOB/A §8 Par. 3). The RAL Quality Assessment GZ 961 contains requirements to be met by: • • • • •
personnel equipment training and development programme charging of follow-up firms purchase of deliveries and foreign supplies/services
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April 2004
ATV-DVWK-A 116, Part 1________________________ The customer can revert to a “System for quality testing of deliverers or firms” according to the EG-Standard dd. 17.09.1990 (Appendix C of DIN EN 1610) for example the Quality Assessment Kanalbau e.V. Firm The staff/ of a firm must be adequately educated and must be able prove having frequented up-to-date development and training programmes, in order to assure correct execution of the assigned tasks e.g. specialist for wastewater technology as well as for canalisation and pipeline laying.
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ATV-DVWK-A 116, Part 1________________________ Vacuum drainage is a special discharge technology which can be under certain circumstances quite cheaper than conventional systems (gravity) with much lower investment costs. In consideration of economics there are, however, also all the follow-on costs to be included such as, for instance, for operation, servicing, write-off, interest etc. The Set of Rules and Standards contains besides the normal normative definitions and information a detailed system description of a vacuum pressure discharge system. Statutory questions are treated/explained as well as details on planning, construction technical execution and operation of vacuum pressure drainage systems. Now the Work Sheet ATV-DVWK-A 116 consists of 3 parts: • • •
Part 1: Vacuum drainage systems outside of buildings Part 2: Pressure drainage systems outside of buildings Part 3: Compressed air cleansed pipelines for the transport of wastewater
Part 1 and 2 of the Work Sheet are supplementary to DIN EN 1091 and are valid only in connection to it. This part of the Work Sheet applies for planning, construction and operation of vacuum drainage systems outside of buildings and contains additional regulations and information.
ATV-DVWK
Deutsche Vereinigung für Wasserwirtschaft, Abwasser und Abfall e.V. Theodor-Heuss-Allee 17 – D-53773 Hennef Telefone: 02242/872-0 – Fax 02242/872-135 E-Mail:
[email protected] - Internet: www.atv.de
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