Phast - Adding a Component from DIPPR.pdf

DNV Software

Adding a Component from DIPPR

This article applies to the following products: SAFETI (Financial/NL/Micro) 6.x PHAST (Financial/Micro) 6.x

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1. Introduction The programme, when installed has 60 components available in the normal user mode and has over 1500 compounds from the Design Institute for Physical Property Database (DIPPR), available in Administrator mode. The DIPPR database contains pure component physical property data for commercially important chemicals. The data included is compiled and evaluated by a project of the American Institute of Chemical Engineers (AIChE), DIPPR. The data in the DIPPR database consists of both property constants and temperature dependent properties. DIPPR components are generally ready to be used in dispersion calculations but may contain missing flammable and toxic data; this information has to be supplied in order to be able to calculate effects. Each component has a unique CAS number assigned to it by the Chemical Abstract Services (http://www.cas.org/). The CAS number is particularly useful because some compounds are published under various names depending on the source, and the name known to the user may not be the same used in the DIPPR list. The CAS number is a unique identifier for each component. Useful websites for CAS numbers include the following: • http://chemfinder.cambridgesoft.com/ • http://www.chrismanual.com/toc.htm • http://www.msdssearch.com/DBLinksN.htm#Foreign%20Language Components from DIPPR can only be added in PHAST and SAFETI administrator mode; the components are added under the System Materials tab. The options below will be available when adding components to the System Materials tab.

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•

Insert a new component - the programme inserts a component with the name

"New Component”. This will not be from DIPPR and all the component properties will be blank. •

Add an existing component - the programme adds a new component from the DIPPR database and missing component properties can be added or existing properties can be edited.

•

Copy an existing component – the programme copies an existing component from the System Materials tab and the properties can then be edited.

Since this document is focused on adding components from the DIPPR database, only the option of adding existing components will be discussed further.

2. Adding components from DIPPR 2.1

Accessing the DIPPR Database through PHAST

The DIPPR database is installed with PHAST, and can only be accessed through the Administration mode. The following are instructions on how to access the DIPPR database from PHAST. 1. Launch PHAST, in administrator mode. Type in the password (default: Technica) and then select Login as Administrator, as seen in the screen below.

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2. Start a new file (through the menu bar under File -> New). The new file will look very similar to the user mode PHAST study, except that after the Map tab in the study tree, there are two new tabs: System Parameters and System Materials tabs.

3. While in the system Material tab, right click on the System Components Folder and through the menu, select Insert -> Component. This will bring up a dialogue box, as shown below which presents the contents of the DIPPR component database and give the user options of adding components.

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2.2

Inserting an Existing Component from DIPPR

The list of components in the DIPPR database are referred to as the DIPPR List, the following are steps for inserting a component from the DIPPR List onto the System Materials. 1. Highlight the desired component from the DIPPR List and click OK. 2. The highlighted component will be added to the System Materials. If the added component has incomplete data, the icon for the component will have a red border. When the component has complete data, there will be no red border around its icon. The properties of each component are grouped into various tabs and it is recommended that each tab be viewed, by double clicking on the component and browsing the tabs, to check for the missing data that the red border is indicating.

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The components that have complete data compiled in the DIPPR database are Allyl Alcohol, Bromine, Ethyleneimine, Fluorine, Formaldehyde, Methyl Mercaptaan and Allyl Chloride. 3. To edit the properties of the inserted component, double click on the component’s icon to open the material properties dialogue. On certain tabs there may be missing data but most of the data necessary for discharge and dispersion calculations are available for each component. All the fields outlined in red must have content before the component can be used in any calculations. The next section of this document will give more information about the missing data and possible sources for them.

3. Missing Component Properties Generally, there are four component tabs which require further information, these are: •

General Tab

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3.1

•

Flammable Tab

•

Toxic Tab

•

Water Tab

General Tab

Clicking on the General tab gives a dialogue screen similar to the one below.

Guidelines for the missing data in this tab are discussed below.

3.1.1

Is the component flammable/Toxic?

The user must specify whether the component is flammable, toxic, both, or neither. If unsure of whether the component is flammable or toxic look at the second tab; if the LFL, UFL or

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heat of combustion exists, the component is most likely flammable.

3.1.2

Reactivity with the Atmosphere?

The user needs to choose from the list available (Strongly Reactive, Not strongly Reactive or HF only). The only type of reaction with the atmosphere currently modelled in the programme is the association reaction with Hydrogen Fluoride and this is covered in the Association tab section. Any other option selected is only for the user’s reference and is not used in the programme.

3.2

Flammable Tab

Clicking on the Flammable tab gives a dialogue screen similar to the one below

If the flammable properties are difficult to find, general guidelines on input data are discussed below; alternatively, properties from a similar component can be used but are not strongly

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recommended. All missing flammable properties in this tab are only used for pool fire calculations, with the exception of TNT efficiency which is used only in vapour cloud explosion calculations.

3.2.1

How to Specify TNT Efficiency?

Sources of Component-Specific TNT Efficiency Values include the following: • Handbook of Chemical Hazard Analysis Procedures (ARCHIE User’s Manual), Published by FEMA / DOT / EPA, 1989 • FM Global Property Loss Prevention Data Sheet 7-42, April 1994, pages 13-14. The table below shows TNT efficiency values for some commonly used compounds and their respective sources.

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Specific TNT efficiency inputs: • The value of the component-specific citation should be used if available. When not available, a typical value of 10% is suggested.

3.2.2

How do I determine what type of pool fire flame occurs?

The type of pool fire flame (luminous or smoky flame) from the combustion of the component needs to be added. Pool fire flame inputs: • ARCHIE Manual Suggests: “components with a normal boiling point (NBP) above 30 °F typically burn with sooty flames” • DNV Suggests: “light components (molecules up to 4 carbon atoms) produce a luminous flame; heavier components produce smoky flames”. A conservative approach is to enter “luminous” for all fuels (for highest thermal radiation). However, it is better to use number-of-carbon-atoms or NBP correlation.

3.2.3

How do I specify emissive power length scale?

There is very little guidance from literature (8.33 m value cited occasionally). Emissive Power Length Scale inputs: •

DNV Suggests: 2.75 m for luminous flames, 8.33 m for smoky flames

3.2.4

How do I specify minimum surface emissive power?

Pool fire modelling requires minimum surface emissive power and emissive power length scale, given by the correlation below: E a = E max ⎛⎜ e ⎝

−D

L

−D ⎞ ⎞⎟ + E ⎛ L ⎟ smoke ⎜1 − e ⎠ ⎝ ⎠

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Where, Ea = average emissive power of hydrocarbon pool fire Emax = maximum surface emissive power of fuel, kW/m2 D = pool diameter, m L = emissive power length scale, m Esmoke = emissive power of smoke, 20 kW/m2

The Maximum Surface Emissive Power sets an upper limit to the surface emissive power used in the radiation modelling, and the Scale Length is used for calculating the emissive power for a fire with a given diameter. Values of the Scale Length for a number of materials are given in Mudan, K. S. and Croce, P. A., 1988, Handbook of fire protection engineering, Society of Fire Protection Engineers, 1988, ch 2-4. •

ARCHIE Manual cites work by Alger and Huggland, given by the correlation below: E max = 117 − TNBP (0.313) Where, TNBP = normal boiling point in °F The table below gives the comparisons between the Alger and Huggland correlation and known values. TNBP

Alger/Huggland

Observed

LNG

-258

198

220

LPG

-44

131

160

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The Alger and Huggland estimated values are lower than those observed by about 16%. Therefore, modifications can be made to establish a modified Alger and Huggland correlation; if both Parameters are increased for the revised correlation it gives: E max = 136 − TNBP (0.364) Maximum Surface Emissive Power Inputs: •

The modified Alger and Huggland values are a good choice as they are component specific. However, the DNV recommended values can also be used.

•

DNV Suggests: 140 kW/m2 for smoky flames, 170 kW/m2 for luminous flames

3.2.5

How do I determine the maximum burn rate?

Maximum burn rate is the equivalent of the maximum mass loss rate from a pool fire. The program uses the correlation by Burgess and Hertzberg to estimate maximum mass burning rate, given by the correlations below: MBR =

0.001(∆H C ) ∆H V

*

∆H V = ∆H V + c PL (TNBP − Tamb ) *

Where, ∆Hc = heat of combustion ∆Hv = heat of vaporization cPL = specific heat capacity of the liquid TNBP = normal boiling point temperature Tamb = ambient temperature

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The burn rates of some commonly used components are as follows:

The graph below shows the relationship between mass burning rate on land and thermochemical property of the fuel.

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Maximum Burn rate inputs: •

DNV Suggests: It is recommended that component specific values are used if available but the correlation can also be used. To use the correlation, enter value of “0”.

3.2.6

How do I estimate pool fire burn rate length?

Actual burning rate (ABR) is less than or equal to maximum burning rate (MBR), according to Babrauskas Correlation: −D ABR = MBR⎛⎜1 − e L ⎞⎟ ⎝ ⎠

Where, ABR = actual burn rate, kg/(m2*s) MBR = maximum burn rate, kg/(m2*s) D = pool diameter, m L = characteristic pool scale length, m The burn rates, length (m), of some commonly used components are in the table below.

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Pool-fire burn rate length inputs: •

DNV Suggests: specific values are used where possible. A zero value is not accepted. If no data is available, then 0.1 m (“conservative” default value) With L = 0.1 m, ABR ≈ MBR for any pool with diameter > 0.3 m (1 foot).

3.3

Toxic Tab

Clicking on the toxic tab will give a dialogue screen similar to the one below.

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Toxic properties are not compulsory for toxic only components. If no data is entered here, users will not obtain any toxicity data and an additional input to stop the dispersion calculations will be required in the case input. The additional input is specified as either a concentration of interest or a distance of interest. Guidelines for filling the missing data in this tab are as follows: 3.3.1

How do I find ERPsG value?

ERPG values are established for about 100 compounds, current values can be found at http://www.aiha.org/Committees/documents/erpglevels.pdf For the remaining components you can use Temporary Emergency Exposure Limit ( TEEL-1,

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-2 and-3) values. They are an “unofficial” but invaluable supplement to ERPG values. TEEL values have been developed by Westinghouse (under Contract to the US Department of Energy)

for

2200+

components.

Current

values

can

be

found

at

http://www.eh.doe.gov/chem_safety//teel.html ERPG inputs: DNV Suggests: use specific ERPG values where available, if no ERPG values exist then TEEL values may be used. Otherwise these inputs can be left blank as they are not required for dispersion calculations.

3.3.2

How do I find IDLH and STEL values?

The Immediately Dangerous to Life and Health (IDLH) and Short Term Exposure Limit (STEL) can usually be found on the internet. Download

“NIOSH

Pocket

Guide”

for

IDLH,

STEL,

and

other

values

at

http://www.cdc.gov/niosh/npg/. Another good source for IDLH/Odour data is the “3M Respirator Selection Guide” at http://www.occupationalhazards.com/safety_zones/50/article.php?id=11631 DNV Suggests: this is an optional input and should only be used if suitable data is available

3.3.3

How do I find Probit coefficients ?

Probit coefficients are used to predict the probability of fatality from exposure to a toxic component. Generally accepted values have been established for only 20 - 30 components. A crude technique does exist for estimating values for other toxic components in “Methods for the Determination of Possible Damage “(Green Book), CPR 16E, Section 5.2.2 For this method LC50 data (preferably for humans) is necessary. A good internet resource for LC50 data is http://www.cdc.gov/niosh/idlh/intridl4.html Given the LC50 data its value must then be translated from the cited exposure length, t, to a 30 minutes exposure basis, this is given by the correlation below:

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⎛ t ⎞ LC 50 (30 min) = LC 50 (t min) × ⎜ ⎟ ⎝ 30 ⎠

0.5

If LC50 (30 min) is for non-human species, it must be translated into human, by the correlation below: LC 50 (human) = f × LC 50 (animal ) Where, ƒ < 1 (as listed in Green Book) Then the Probit coefficients can be estimated as follows N =2

(

A = 5 − ln 30 × LC 50 (human) 2

)

B =1 Profit coefficient inputs: •

DNV recommends: established probit coefficients be used where possible. Otherwise they can be estimated using the “Green Book” method as described above or left blank as they are not compulsory fields.

3.4

Water Tab

Clicking on the water tab gives a dialogue screen similar to the one below

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The component will be missing information about interaction with water. The first four inputs are only used if the release forms a pool on water: •

Liquid-Water Surface Tension

•

Solubility in Water

•

Heat of Solution

•

Water Heat Transfer Coefficient

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Input values for the fields in the water tab: •

It is suggested to perform a good literature search to find these values. If the release is over land, the inputs can be set to zero; otherwise examine the values for the standard 60 components then reverse-engineer values for the new component.

•

Reaction with Water: there are two choices, None or Raj and Reid

Raj and Reid Model is only valid for ammonia spills onto water. If the component is not ammonia then it should always be set to “None”.

4. Saving the New System Components List The component has now been added in the system materials and it now must be saved. If it is not saved, then when the program is started in normal mode the component will no longer be there. 1. In order to save the information, through the menu bar, click on Options -> Administration -> Update System Materials. See dialogue screen below.

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The program will prompt the user for a description of the changes made. It is useful to note what components have been added or what values have been changed. The program will keep a log of all the changes made to the system materials.

2. The program will then save a copy of the old system materials. It will make a backup copy of the old system materials file every time the list is updated.

3. The program will then update the system materials.

4. The new component will now be available for every file opened in PHAST.

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5. Contact DIPPR For further information on DIPPR, contact AIChE at: Design Institute for Physical Property Data

Karen Elizabeth Person Sponsor Relations, ITA American Institute of Chemical Engineers 3 Park Avenue, 19th Floor New York, NY 10016 USA phone: 212-591-7319 fax: 212-591-8883 email: [email protected] web: http://www.aiche.org

6. Contact DNV Software Technical Support For further assistance on this or any other support issue, please email [email protected].

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