Your Guide to the Safe Handling of Flammable Liquids

April 1, 2009
An important component of fire prevention and safety is the procedures for transferring and disposing of flammables, along with a review of the containers that should be selected.

In the March article, “Your Guide To The Safe Handling Of Flammable Liquids,” we discussed the chemistry of fire and some fire facts about flammable liquids, and concluded with a discussion of both the drum room and point of use containment.

Now we'll turn our attention to the procedures for transferring and disposing of flammables.

Processing plants that require large quantities of flammable or combustible liquids often transfer these materials through closed piping systems. However, far more plants use these substances in smaller amounts and rely on manual methods to transfer the liquids from storage points to workstations. Although manual transfer involves having hazardous materials in open areas, following certain steps and using proper equipment can minimize the danger.

OSHA regulations require approved safety cans to transfer flammable liquids. Its broad criteria define a safety can as “an approved safety container, of not more than 5 gallons capacity, having a spring closing lid and spout cover and so designed that it will safely relieve internal pressure when subjected to fire exposure.”

Dozens of types and sizes of safety cans exist. Selecting the best type for the job is the key to safe and easy transfer and use of flammable liquids.

Flammable liquid transfer applications can be grouped into three categories: general process, gas powered equipment and other equipment using containers with small openings and laboratories and other small capacity uses.


In an industrial plant, flammable cleaning solvents commonly are used to wash parts in bench cans, rinse and wash tanks and automatic washers. This equipment must be refilled periodically.

Often, flammable chemicals that are used in these factory processes are carried from storage areas in Type I single-spout safety cans. Type I safety cans are different from the typical poly gas can you see at your local big retailer or hardware store. They are built to specifications set forth by OSHA and the National Fire and Protection Association (NFPA). Type I safety cans are made of steel or polyethylene and go up to a 5-gallon capacity. Application is the principal criterion affecting size selection. For example, an operator can use a smaller safety can to fill a bench can faster and with less risk of a spill rather than using a 5-gallon can, even though both meet OSHA requirements. Similarly, for filling wash tanks, rinse tanks and other large containers, large-size cans are more efficient.


For machinery or equipment that requires flammable liquids such as gasoline, kerosene or diesel fuel, Type II safety cans equipped with a flexible metal hose should be used to fuel small engines or fill fuel tanks. The hose fits easily into the small opening, eliminates spills and waste and reduces fire hazards.

A Type I safety can, equipped with a funnel hose attachment clipped to the spout, also will suffice. Whether the can is equipped with a built-in hose or requires a separate funnel, both versions offer controlled pouring.


When flammable liquids are dispensed into small capacity containers, the safety cans must be designed to control the rate of flow and the amount of liquid dispensed. Laboratory style cans have self-closing faucets, come in tilt rack or shelf models and allow one-handed operation.

The instant cutoff capability of the faucets provides the control required for filling flasks and other small containers safely and without spills. Flexible metal safety hoses can be threaded into the faucets for added control.

Proper Disposal

Responsibility for flammable liquids extends beyond careful storage and use, and does not end until the materials have been disposed of properly. Solvents, solvent- soaked rags, mixtures of flammable and combustible liquids, etc., do not lose their fire potential simply because they are no longer used. In some cases, they may be more hazardous.

Unfortunately, a worker may be more careless with discarded materials than with new materials. When flammable liquids are handled with this attitude, disaster is invited. For example, if a 55-gallon drum filled with 54 gallons of waste kerosene (a Class II combustible liquid with a flash point above 100° F.) is topped off with a gallon of waste naphtha (a C lass IB flammable liquid with a flash point of about 28° F), the mixture is considered by OSHA to be as hazardous as a full drum of naphtha. Because the vapors of the flammable liquid can form an ignitable mixture with the air, any fire in the mixture would almost instantly involve the vapors of the combustible liquid as well.

Use approved safety containers and proper procedures for disposal. Using open cans or unapproved receptacles to contain these hazardous materials, until they can be removed by a licensed waste service, increases the risk of disaster. It is also a valid cause for OSHA citations and fines.


Flammable liquid waste can be disposed of in a number of ways, depending on the amount. Waste disposal drums are effective when large amounts are involved. These drums may be stored in safety cabinets that have been grounded and vented.

When filled from a steel safety can, disposal drums must be bonded to the smaller container and should be fitted with an automatic pressure relief vent. Special drum funnels, which are fitted with a flame arrester, safely collect waste liquids into the drum, and the large diameter of the funnel minimizes the risk of spills. Instead of using flammable liquid cabinets, spill control pallets may be used to hold the drums.

Smaller volumes of flammable liquid waste may be collected and held in safety disposal cans. Nearly identical to standard safety cans, they have a large-diameter spout to minimize spills during filling, along with a flame arrester to prevent fire intrusion.

Flammable wastes never should be dumped into the sewer system. Not only is it hazardous to the person doing the dumping and all other occupants of the plant, it can spread a fire or a toxic hazard to the entire community. In addition, you are liable for any environmental damage. Therefore, the disposal site and the waste service must be properly licensed.


Cleaning wipes widely are used in many industries ranging from a small auto repair shop to any manufacturing facility, including mega buildings where airplanes are built. These rags used with flammable liquids present a different disposal problem because they are susceptible to ignition from outside sources — heat build-up in accumulated oily wastes can cause spontaneous ignition.

Oily waste cans should be used to help control the flammable liquids spills and assist in the cleanup. Small spills can be wiped up with cloths; saturated rags should then be placed into the oily waste cans for disposal. Oily waste cans are designed to prevent ignition from outside sources or spontaneous combustion. Equipped with self-closing lids that shut via gravity, these containers remain closed when not in use, isolating the contents from any ignition source. The lid blocks air from outside sources and helps snuff out any fires that may start inside the can. Lids can be opened by hand or with a foot treadle.

Rags soaked with flammable liquids have contributed to tragedy:

  • A single-family house under construction was destroyed by an early-morning fire. Investigators determined that the fire started in a garage in a bucket containing cotton rags soaked in linseed oil and spread into the house and up to the second floor. Apparently, the rags combusted spontaneously.

  • A $1.5 million North Scottsdale, Ariz., home was destroyed in a fire that started when wood stain soaked rags near the gas meter spontaneously combusted. Heat from the gas-fed fire was so intense that it melted the joint connecting the sprinklers to the water source and the water never made it inside the home.

Approved oily waste cans are designed with bottoms elevated from the floor to allow air to circulate and heat to dissipate. The volume of waste in the cans, the amount of air available for combustion and the length of time the waste has been in the can, all affect heat generation that precedes spontaneous combustion. Safety demands that waste can be emptied frequently, at least once a day according to OSHA.

Applying these basics about working with flammable liquids in the workplace will reduce fires.

Gary Marcus is vice president of Justrite Mfg. Co. LLC, headquartered in Des Plaines, Ill. He is a veteran of successful industrial and consumer products companies with over 25 years of experience. Justrite has been in the safety products business for over 100 years and is a leading provider flammable and hazardous liquid storage and dispensing products. An educational guide about flammables storage, Justrite's Red Book, is available at no charge. Visit

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