Section 6.0: Flammables & Combustibles
A working knowledge of safe handling and storage of flammables, liquids, gases and combustible materials are essential for successful fire prevention.
This section is provided for the identification, and subsequent correction, of plant deficiencies in the handling and storage of flammables and combustibles to prevent fires.
||Employees must understand the hazards of flammable and combustible materials and proper handling procedures.|
||Management should ensure that precautions, such as the availability of approved covered metal scrap receptacles are provided for use and promptly and properly emptied and disposed.|
||Only approved piping, containers, tanks, and rooms designed, safeguarded, and constructed specifically for the storage and handling of flammable and combustible liquids, including waste solvents, should be allowed for use.|
||When not in use, containers of flammable liquids must be closed to prevent ignition and the creation of hazardous atmospheres, and stored in approved cabinets, containers, and buildings.|
||Flammable liquid drums must be grounded and dispensing containers must be electrically bonded during dispensing or transfer of the flammable liquid to prevent the build-up of an electrical charge.|
||Electrical fixtures, switches, and circuits inside a flammable and combustible liquid storage room must be appropriate for hazardous locations (explosion-proof).|
||All inside flammable and combustible liquid storage rooms must be equipped with either a gravity or a mechanical exhaust ventilation system designed to provide at least six air changes per hour. This prevents the build-up of an explosive atmosphere.|
||Combustible dust and particulate should be removed by vacuuming to prevent the creation of a hazardous atmosphere. Sweeping or blowing dust with an airline is not acceptable.|
||Only personnel trained in chemical safety, bonding, grounding, and fire prevention should transfer or withdraw flammable and combustible liquids.|
||All use and storage locations of flammable and combustible materials and wherever danger could be caused by ignition must be identified and posted with appropriate "NO SMOKING" signage. Management must ensure that all personnel adhere to the posted safety warnings.|
||All spills must be cleaned promptly and properly.|
Flammable and combustible liquids are frequently contributing factors in major fire losses. Records show that they are involved in 15 percent of all fires and explosions in industrial plants.
Before the hazard from flammable or combustible liquids can be controlled, the material must be identified. Only then can an evaluation of its properties be made and the extent of the hazard determined. Naturally, the more severe the hazard, the more care and control needed to guard against it.
There are a number of excellent references that can be used to help determine the severity of the hazards involved.
Once the characteristics of a material have been determined, it must be decided how best to use and store it. Here are some general guidelines that may be adapted to your specific needs.
The major hazard associated with the storage of flammable and combustible liquids is accidental discharge. This may be due to overpressure of the container in a fire, rupture of the container from mishandling, or rupture of transfer piping.
Flammable and combustible liquids often are stored in tanks, drums, or small containers, depending on the operation.
Inside storage tanks present a severe fire exposure to the building and should be avoided whenever possible. If inside tanks are absolutely necessary, the following precautions should be taken:
- Location: If at all possible, the tanks should be located in a grade-level room that is isolated from the rest of the building with a two-hour fire-resistant material. This room should be well ventilated, have drains, and protected by an automatic extinguishing system.
- Piping Connections: All connections for tank openings and piping systems should be liquid tight and all vents and fill pipes should terminate outside the building at least five (5) feet from any building opening. Each tank should be equipped with a means of preventing overflow into the building. All piping systems must be grounded and bonded.
Drums and Containers:
Drums usually contain 55 gallons, while containers are smaller, ranging down to less than one gallon.
Unopened containers normally present a moderate fire hazard. It is when they leak or are exposed to excessive heat that the hazard becomes severe. Depending on the design of the containers, they may react to heat in several ways: come apart; burst with explosive violence; or become a rocket, spreading flaming liquids over a large area.
The potential fire risk from container storage is considerably lessened if the containers are segregated from the rest of the operation by distance or construction. Storage outside or in detached buildings is preferred. If the storage must be inside, the preferred method is in structurally isolated rooms. These rooms should have liquid-tight raised sills, a ventilation system, and electrical wiring suitable for the class of liquid.
A storage cabinet designed and constructed properly may be used for small amounts of flammable and combustible liquids in original shipping containers.
The use of safety cans for storage is not suggested unless they are kept in a storage cabinet or separate isolated room.
Handling and Use:
The major objective of any handling or dispensing operation involving flammable or combustible liquids is to keep the quantity of liquid to a minimum to avoid escape in case of an accident.
Pumping the liquid through a closed piping system is considered the least hazardous method to transfer large quantities. Positive displacement pumps are preferred because they provide a reasonably tight shutoff and prevent accidental siphoning of the liquid when not in use. Centrifugal pumps designed for this purpose are acceptable, but they cannot provide a tight shutoff if taking suction under head. This could result in siphoning from the tank when the pump is not in use.
Gravity systems are sometimes used for certain operations, but are more difficult to equip for prompt shut-off and are more susceptible to accidental spills.
Dispensing flammable liquids at the point of use in the main building area usually results in releasing flammable vapors that may create a fire hazard. A preferred arrangement is to set up a protected and ventilated dispensing area and to bring all containers to that area to be filled.
The suggested method to dispense liquids from drums or five-gallon cans is with a laboratory-tested hand pump. This minimizes the possibility of spills or leaks. An acceptable method of gravity dispensing is approved or listed self-closing faucets or drum vents are used.
Approved or listed safety cans should always be used for handling flammable and combustible liquids outside the dispensing area. Open containers should NEVER be used for dispensing or handling.
The lack of properly trained personnel is one of the major causes of flammable and combustible liquid fires. The safety of an operation using these liquids depends largely on the effectiveness of an employee training program, which should include, but not be limited to, the following:
- Thorough indoctrination of the hazards involved
- Normal and emergency operating procedures
- Importance of good housekeeping
- Procedures for control and cleanup of leaks and spills
- Procedures for disposal of waste materials.
The major objective of a flammable liquids loss control program is to confine the liquids and vapors within the equipment and to minimize the effects of a leak or spill by draining the liquid to a safe location. The following five methods are used to achieve this:
- Use only vapor- and liquid-tight equipment designed for handling flammable or combustible liquids.
- Handle small amounts of liquids only in approved or listed safety cans.
- All drainage systems must be contained.
- Disposal of flammable liquids must be conducted with appropriate procedures and containers.
- Flammable storage drains should discharge into an approved container/tank; flammable liquids must not be allowed to drain into the ordinary building container, tanks, or drains.
This is essential to prevent a buildup of vapors, which could result in a severe fire or health hazard. Mechanical ventilation is preferable, but natural ventilation is acceptable under certain conditions.
Control Ignition Sources:
It is important to control or eliminate all potential ignition sources in areas that might contain an accumulation of vapors. Following are some of the precautions that should be taken to minimize the probability of ignition:
- Electrical equipment and wiring should be suitable for the hazard.
- If a heating operation is necessary, use only indirect heating methods.
- Do not allow any open flames, hot surfaces, radiant heat sources or friction- and spark-producing equipment in flammable liquid areas.
- Provide grounding and bonding for all equipment handling using these liquids.
- Establish a maintenance program to assure that all equipment and safety controls are functioning satisfactorily.
If a flammable liquid must be used for an operation, management must exert close control over the storage, handling, and use of this liquid. This is best done by proper training of personnel, confinement of the liquids and associated vapors to selected areas, ventilation to prevent vapor build up, control of potential ignition sources, and protection of the area with an extinguishing system.
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