The two primary hazards associated with flammable and combustible liquids are fires and explosions, either of which could injure or kill scores of employees and do major damage to your facility. But flammable and combustible liquids can be hazardous in other ways, as well. Some vapors are toxic, and splashes on the skin or in the eyes may cause irritation or be poisonous if absorbed.
Because of these hazards, OSHA developed a standard to protect workers from the dangers of flammable and combustible liquids (29 CFR 1910.106). If you use these liquids for spray finishing or in dip tanks, you’ll also want to look at Sections 1910.107 and 1910.108, respectively.
Here are a few examples of regulated flammable and combustible liquids:
- Gasoline and diesel fuel
- Many commonly used solvents
- Alcohol (ethyl, isopropyl, and methyl)
- Paint and lacquer thinners and strippers
Key Words
Let’s begin with a review of terms:
A flammable liquid is any liquid having a flash point below 100ºF. Flammable liquids are also known as Class I liquids. Class I liquids are divided into three subclasses:
- Class IA includes liquids having flash points below 73ºF and having a boiling point below 100ºF.
- Class IB includes liquids having flash points below 73ºF and having a boiling point at or above 100ºF.
- Class IC includes liquids having flash points at or above 73ºF and below 100ºF.
Can your managers and employees detect the causes of 25 different real-life accidents, each in a different safety area, direct from OSHA records? Find out, and have them learn hazard analysis while they’re at it, with BLR’s OSHA Accident Case Studies program. There is a separate PowerPoint® for each case. Try it at no cost and no risk.
A combustible liquid, on the other hand, is any liquid having a flash point at or above 100ºF. Combustible liquids are divided into two subclasses:
- Class II liquids include those with flash points at or above 100ºF and below 140ºF.
- Class III liquids include those with flash points at or above 140ºF.
The flash point is the minimum temperature at which a liquid gives off vapor in sufficient concentration to form an ignitable mixture with air near the surface of the liquid. The lower the flash point, the more likely liquid is to catch fire and burn.
Flammable (or explosive) limits also affect a flammable or combustible liquid’s fire and explosion potential. These limits set the range between the lowest and highest concentrations of vapor in air that will burn or explode.
Vapor density is another important issue. Most flammable liquids have a vapor density greater than 1, which makes them especially dangerous because their vapors are heavier than air. This means they tend to sink to floor level and accumulate there when released, which increases the potential for ignition.
ID Check
The three primary ways for your employees to identify flammable and combustible liquids in the workplace are:
- Material safety data sheets (MSDSs) will show the flash point, flammable limits, and vapor density; enumerate safety and health hazards; and give safe handling and storage instructions.
- Container labels will provide a warning that a liquid is “FLAMMABLE” or “COMBUSTIBLE,” or use the color red to warn of the fire and explosion hazards.
- Warning signs posted in areas where flammable or combustible liquids are used or stored are usually in red letters and warn that there are hazardous materials present that can burn or explode if ignited.
Safe Storage
OSHA requires flammable and combustible liquids to be stored in fire-resistant buildings, rooms, or cabinets. Storage areas must be located away from potential ignition sources such as electrical panels and furnaces, and they must also be marked with warning signs and be well ventilated to prevent buildup of vapors.
Inside the storage area, aisles must be at least 3 feet wide to ensure easy movement that reduces the potential for spills or damage to storage containers, and to provide access for firefighters and a ready escape route for employees.
Try BLR’s unique OSHA Accident Case Studies PowerPoint program at no cost or risk. Find out more.
Fire extinguishers must be located near, but not in, storage areas. If extinguishers are too close to storage areas, the extinguishers may be inaccessible once a fire has started.
In addition to these regulatory requirements, your employees need to know and follow these safe storage rules:
- Keep storage areas free of other combustible materials, such as cardboard, paper, and wood.
- Use only approved, properly labeled, closed containers or portable tanks for storage.
- Avoid stacking containers; if stacked, they may tip over and spill.
- Report leaks or spills immediately.
- Never smoke or bring an open flame or other ignition source into a flammable and combustible liquid storage area.
Tomorrow we’ll look at rules for the safe handling of flammable and combustible liquids—and at an actual case from OSHA’s files you can use it to drive home the importance of those safety measures.