One of the functions of the Philadelphia (PA) Fire Department’s Haz Mat Administrative Unit is to assist fire companies and other units with inspections. As part of the inspection, I generally ask the building manager the following questions:

  • “Do you have a copy of the current fire code?” This is not a requirement, but it should be.
  • “Do you have any hazardous materials on the property?” A hazardous material is classified as a substance that presents a physical or a health hazard. Examples of materials that present physical hazards would be explosives, cryogenic liquids, and compressed gases. Radioactive materials, corrosives, and toxic materials would be under the classification of substances that pose health hazards.

Certain hazardous materials that exceed specified amounts would be considered as part of a “High-Hazard Use Group,” for which a permit would be required. Facilities that require permits must develop and maintain on-site a “Hazardous Material Management Plan.”

  • “May I see the current Certificate of Occupancy (CO)?” This document would establish that the occupancy was inspected and is being used for the purposes stated in the CO—in other words, it is not designated as a car wash and operating as a chemical laboratory.

If the building manager says only some regular cleaning products and some acetylene, a flammable compressed gas, are on the premises, I ask to see them. To the building manager, “regular cleaning products” could mean 90-percent concentrated sulfuric acid. As for the flammable compressed gas, several criteria must be considered before determining if the occupancy is in compliance with the fire code, as is illustrated by the case presented here.


According to the 1997 Philadelphia Fire Code and amendments, any welding or “hot work” requires a permit, along with a few safety precautions.

One precaution is that all combustible materials such as floors, ceilings, and walls be protected from sparks. Another is to have a fire watch capable of operating portable fire extinguishers or a fire hose to remain 30 minutes after the welding or cutting operations have been completed. A signed inspection report attesting to these facts should be filed and available for inspection by the code official.


Firefighter and occupant lives are our primary concern. Acetylene has a flammable range of 2 to 80 percent. Once it finds an ignition source, a fire will occur.

Acetylene is a colorless gas and at 100-percent purity is odorless, but commercial acetylene has a distinctive garlic-like odor added to assist in identifying a leak. If you respond to a call for a leaking cylinder, immediately evacuate all personnel from the danger area. If possible, remove all ignition sources; this is risky because of acetylene’s extremely wide flammable range.

An even safer approach would be to reduce vapors with a fog or fine-water spray and, if possible, shut off the flow of acetylene.

Another approach would be to move the leaking cylinder to a well-ventilated area; this is also very risky. Before entering the area, especially a confined area, check the atmosphere with an appropriate device. National Fire Protection Association (NFPA) 704, Standard for the Identification of the Fire Hazards of Materials for Emergency Response, 1996, rates acetylene as follows: 1—health, 4—flammable, and 3—reactivity. The rating numbers appear in a diamond-shaped, color-coded symbol, with “4” indicating the worst.


According to the Philadelphia Fire Code and amendments, compressed gases are restricted by total volume and the number of control areas (a control area is an area bounded by a one-hour fire rated enclosure)—for example, a total of 750 cubic feet of flammable compressed gas is permitted in one control area; the number of control areas is reduced the higher up you go in a building. The first floor, for example, may have four control areas, each with 100 percent of the permitted amount, so 750 cubic feet of flammable gas per control area 2 4 control areas = 3,000 cubic feet on the first floor.

The second floor may have three control areas, but the permitted percentage is reduced to 75 percent. Therefore, 750 cubic feet 2 3 = 2,250 cubic feet reduced to 75 percent, or 1,688 cubic feet.

Now, the third floor is reduced to two control areas and 50 percent; 750 cubic feet 2 2 = 1,500 cubic feet, but at 50 percent, for a total of 750 cubic feet. The fourth, fifth, and sixth floors also have two control areas, but the amount is reduced to 12.5 percent, so 750 cubic feet 2 2 = 1,500 cubic feet reduced to 12.5 percent, for a total of 187.5 cubic feet.

There are exceptions to the exemption. If the building is sprinklered, the exempt amount can be doubled, and if within a gas cabinet, you can double again. So, let’s do the math again according to Table 1.

These are the real numbers. What did we find? We found six 300-cu. ft. cylinders, or 1,800 cubic feet on the sixth floor. Under the code, a total of 93.75 cubic feet per control area is permitted; there are two control areas, for a total of 187.5 cubic feet. The building was sprinklered; therefore, we are at 375 cubic feet, but the gas cylinders are out in the open, so the gas cabinet exemption does not apply. This building is in violation relative to the quantity of flammable compressed gas on the property. The building owner has 1,800 cubic feet on the sixth floor but is permitted only 375 cubic feet.


  • Know what constitutes a violation. Some violations are just common sense—a flammable gas on the sixth floor? Well, maybe. But six cylinders on the sixth floor?
  • Know how to do the math, because there are always exceptions. The building manager probably will not know the requirements for storing “Flammable Compressed Gases” because it is not required that the occupant have a code book.

RON R. RAGEN is a lieutenant with the Philadelphia (PA) Fire Department’s Haz Mat Administrative Unit.

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