API 685 vs API 610

API 685 vs API 610

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Mechanical Forums by Category: Rotating Equipment: Pumps Highlights Off

 API 685 vs API 610 REPLY Print Subscribe Share More Actions Collapse Thread Nathan Venter

API 685 vs API 610

4-Sep-2008 02:25 AM Response Required: 11-Sep-2008

When do API 685 pumps become more competitive than API 610 pumps? Which capacities , Head & fluids characteristics should I look for to compare API 685 to API610 + Sealing Systems. I would like to to compare a API 685 Canned Motor Pump to a API 610 Centrifugal Pump which has a Plan 53B sealing system. The Liquid is hazardous,-Butane. Flow rate 40 m3/h. Head is 288m. I am particulay interested in hazardous fluids containment , cost and maintenance.

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API 685 vs API 610

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Stanislaw Krzyzowski

. . RE: API 685 vs API 610

8-Sep-2008 01:18 AM

Nathan, Generally I agree with Gabriel's post; however I have a different opinion about sealles pump reliability. External oil lubricated bearing is better than internal with pumped fluid lubrication. If API 610 is selected, then it will be minimum the 2 stages pump of Between Bearings type, so two dual seal arrangement is necessary. If there is permitted to inject to the pumped Butane a small quantity of barrier fluid, then API Plan 53B is adequate. If no contamination is required so API Plan 52 should be applied. If sealless canned motor type is chosen, then it will be also a multistage pump. Sealless type this is a sensitive pump. This can be used under a special arrangement and protection only. I have touched several damages of this type pump. For all of similar cases if sealed pump would be used, then no problems were occurred. Sealless should be preferred for really dangerous liquid means as toxic. Mostly a first estimation says - sealed pump is more expensive than sealless, but if a sealles pump must be equipped with cooling system, bearing temperature monitoring and dry run monitoring, there can occur that sealless pump can be more expensive than sealed pump (regarding purchase and maintenance). Regards

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API 685 vs API 610

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Gabriel Popescu

. . RE: API 685 vs API 610

7-Sep-2008 02:37 AM

Hi Nathan Your application require a multistage pump. API 685 fully covers only the single stage overhung pumps. However there are pump manufacturers which are using the API 610 requirements for multistage pumps and claim that they are offering API 685 multistage pumps. Basically there are two types of pumps covered by API 685 - canned motor pumps - magnetic coupling pump Special consideration should be given to the following: - API 685 pumps have product lubricated hydrodynamic bearings. An internal circuit provides the flow needed for bearing lubrication. Therefore particular characteristics of the fluid such as, solids, magnetic particles and crystal or polymer formations must be communicated to the pump vendor - Both the canned motor and the magnetic coupling are generating heat while running. This heat - added to that generated by the hydraulic losses in the pump- is removed by the same internal circuit which is lubricating the bearings. If the vapor pressure of the pumped fluid is variable with the temperature the risk of vaporization in the bearings must be considered, especially if the bearings are in a low pressure region of the pump. API 685 pumps are providing the following advantages: - "Zero" leakage. Secondary containment design and leakage monitoring devices are available. - Simpler construction and less space required as they avoid the need for seal external systems. - Very low noise - Internal bearings are generally cheaper then double mechanical seals. - According to some statistics provided by pump vendors they are more reliable than the pumps with double mechanical seals However there are also some disadvantages - They have a lower efficiency as they are not designed for efficiency but for "zero" leakage. - They are more expensive then traditional pumps with single mechanical seals, but they become competitive when the application requires API 682 double mechanical seal systems. - They are limited in terms of power. There are only few manufacturers for powers above 75kW - Samarium cobalt magnets are limited to 180degC. Special magnets are required above. - Canned motor pump with external cooling circuits may be proposed for temperatures above deg C. - They are more susceptible to low flow vaporization, and will require special designs for flashing or particle contaminated liquids. - Special care is required during the commissioning procedure in order to avoid the usual dirt and solids to enter in the pump. - Maintenance personnel might be not familiar with these new

Modified: 7-Sep-2008 02:42 AM

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API 685 vs API 610

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types of pumps. - Magnetic couplings might require special tools for mounting and dismantling. - Mechanical seals may be repaired. Bearings cannot be reused. - For multistage "traditional pumps" bearings and mechanical seals replacement might be performed on site without removing the whole pump. In most of the cases API 685 pumps require to be entirely removed in order to replace the bearings. However they are relatively small machines and this might be a good opportunity to inspecting the internals also. - On canned motor pumps traditional "mechanical" interventions, e.g. bearings replacement, require dismantling of the power and instrument cables. Therefore certified electric personnel might be needed. For your particular application - butane- 40m3/h - 288m/h I think that a canned motor pump will be a reliable and competitive solution. To be certified for hazardous environment a temperature probe must exist on the motor cooling and bearing circuit and also a liquid presence detector (level switch) to avoid the dry running. A pressure switch might be added on the motor casing which acts like a secondary containment envelope Be sure that the internal bearings (probably 3 in this application) are in a pressurized region. Personally I would give preference to graphite bearings. Silicon carbide bearings might damage the pump internal if broken. Gabriel Popescu Like

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API 685 vs API 610

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John Pustay

. . RE: API 685 vs API 610

8-Sep-2008 07:21 AM

I'd like to expand on Nathan's question if possible as a local Client just asked a similar question - what is Fluor's experience with actually using the sealless pumps for general, small hydrocarbon and miscellaneous refinery services? (i.e. flare K/O, sour water, caustic, small benzene and other hydrocarbon services?) Like

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