I have a question regarding the need to provide electrical classification for a building using Class 1A flammable liquids.

For this building, 4 gallons could be out in use (located anywhere in the building). The MAQ is 10 gallons. I have discussed this with NFPA 30 committee, the manufacturer, and the AHJ (who is a knowledgeable FPE). They have all determined that even if the MAQ is not exceeded, electrical classification is required if a flammable/explosive mixture could be present.

The NFPA 30 staff directed me to a provision in NFPA 497, Section 5.5, that if the materials will not reach 25% of the lower flammable limit (LFL), this could be utilized to justify not providing classified electrical fixtures.

Does anyone know how to do this calculation, or know of firms that can be hired to do this?

I am an FPE and do not know how to perform it, and I have spoken with other FPE’s who also are not aware. The gentleman I spoke with at NFPA 30 agreed it would be by an industrial hygienist or a chemical engineer and not an FPE.

But does anyone know any that can be hired for a one-off calculation, or have a place where I could learn how to perform it myself (NFPA reference, SFPE article, course, etc.?).

Thank you!

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Use Alpert's Correlation to determine the maximum temperature (in degrees Celsius) of a ceiling jet a a point 1.3 meters (horizontally) from a 1.8 MW fire which burns within a 2.2 m tall room. Assume the virtual origin is at floor level and an ambient temperature of 22 deg C. 
a. 25 deg C
b. 78 deg C
c. 326 deg C
d. 384 deg C

Solution | Posted 10/09/20

White Oak wood having a density of 450, moisture-content of 25% is exposed to a standard fire (ASTM E119) test for 2 hours. What is the expected char depth most nearly?
a. 1 mm
b. 64 mm
c. 78 mm
d. 224 mm

Solution | Posted 10/02/20

Use Alpert's Correlation to determine the maximum temperature (in degrees Celsius) of a ceiling jet at a point 1.3 meters (horizontally) from a 1.8 MW fire which burns within a 2.2 m tall room. Assume an ambient temperature of 22 deg C.
a. 25 deg C
b. 78 deg C
c. 326 deg C
d. 384 deg C

Solution | Posted 09/18/20

A liquid storage tank rupture results in a fire containing an open 45 gallon (130 kg) tank containing animal fat. Using gross heat of combustion, estimate the time it would take to burn the remaining fuel without interruption if the tank is half filled and the fire is approximately 2.45 MW.
a. 1.2 seconds
b. 11 minutes
c. 18 minutes
d. 17.6 hours

Solution | Posted 08/13/20

Solution | Posted 08/07/20

Of the following substances, which would have the greatest total heat output for the same amount of mass?
a. ethane
b. methanol
c. toulene
d. acetone

Solution | Posted 07/24/20

The essence of the fire process is an exothermic reaction which releases heat and other products. Oxidation which takes place with reactants in the gas phase, as opposed to the solids phase, results primarily in what kind of combustion?
a. flaming
b. smoldering
c. detonation
d. backdraft

Solution | Posted 07/23/20

Use Alpert's Correlation to determine the maximum temperature (in degress Celsius) of a ceiling jet at a point 1.3 meters (horizontally) from a 1.8 MW fire which burns within a 2.2 m tall room. Assume an ambient temperature of 22 deg C.
a. 25 deg C
b. 78 deg C
c. 326 deg C
​d. 384 deg C

Solution | Posted 10/22/19

White Oak wood having a density of 450, moisture-content of 25% is exposed to a standard fire (ASTM E119) test for 2 hours. What is the expected char depth most nearly?
     a. 1 mm
     b. 64 mm
     c. 72 mm
     d. 224 mm

Solution | Posted 08/13/19

In preparation for the PE Exam, the fire dynamics content is my weakest subject. I am looking to take some classes on fire dynamics, do you have any suggestions?

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The amount of energy required to raise the temperature of 1 kg of fluid by 1 deg C is:
a. Conduction Coefficient
b. Enthalpy
c. Entropy
d. Specific Heat

Solution | Posted 07/23/19

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Solution | Posted 06/27/19

The temperature where the vapor pressure of a liquid is the same as the surrounding atmospheric pressure is which of the following?
a. boiling point
b. fire point
c. flash point
d. lower flammability limit

Solution | Posted 07/05/18