Use of Storage Cabinets for Flammable Liquid Safety
How can you properly use flammable liquid storage cabinets in industrial facilities to store flammable and combustible liquids?
BY SIMON FRIDLYAND
The maintenance experts widely use flammable and combustible liquids in their daily work. The storage of flammable liquids, dispensing, and usage are regulated by fire codes and occupational health and safety laws. The regulations allow the storage of flammable and combustible liquids in plants in the following areas:
* Specially designed storage rooms, in closed containers only, where dispensing is not allowed.
* Specially designed rooms for storage and dispensing of flammable liquids, where dispensing is allowed (in this instance, the room must be equipped with explosion-relief walls and meet other requirements).
* In the open, in closed containers only in extremely limited quantities in situations where handling flammable and combustible liquids is secondary to the primary activity of manufacturing.
* Flammable Liquid Storage Cabinets
This article focuses only on the storage of flammable liquid in the flammable storage locker, flammable liquid safety, and combustible liquid storage. The units for storing flammable/combustible liquid containers serve the following purposes:
- The protection of flammable/combustible liquids against flash fires;
- The prevention of excessive internal temperatures in the presence of fire;
- The containment of spilled flammable liquids to prevent the spread of fire.
Keeping in mind the guidelines, flammable liquids’ storage must bear ULC or CUL labels as evidence of compliance with Canadian standards. The storage is usually made of metal, having a double wall construction with a three-point door latch and a liquid-tight door sill raised at least 50 mm above the floor.
Do flammable storage cabinets need to be vented?
Storage cabinets also are usually equipped with vents, which are normally plugged in by the cabinet manufacturer. While cabinet manufacturers may provide facilities for venting, ventilation for flammable liquid storage is not required or recommended.
Therefore, venting a flammable safety cabinet is not necessary for fire protection purposes. Flammable and combustible liquid storage units are designed to protect the internal contents from a fire outside the storage unit. An improperly vented chemical storage could compromise the ability of the cabinet to protect its contents from fire.
According to NFPA 30 (Flammable and Combustible Liquids Code) 6.3.4, “The cabinet is not required to be vented for fire protection purposes. However, the following shall apply: (a) If vented for whatever reason, the cabinet shall be vented outdoors or to the fume hood exhaust duct in such a manner that will not compromise the specific performance of the cabinet. (b) If the cabinet is not vented, the vent openings shall be sealed with the bungs supplied or with bungs specified by the manufacturer.”
If the users decide to vent a cabinet to store, at the very minimum, venting must incorporate the following steps:
* Remove both metal bungs from the sides of the cabinet and replace them with flame arrester screens (normally these come with the cabinet).
* Connect the bottom opening to the exhaust system using rigid metal piping equivalent to or better than that used in the construction of the cabinet. The cabinets shall not be vented directly into the fume hood. Piping must have an inner diameter no less than that of the opening and be threaded to match the hole that’s manufactured into the tank. If needed, the piping may have to be welded in place. Riveting or fastening to the locker may compromise the fire protection rating of the cabinet. PVC or plastic piping shall not be used since it cannot withstand high temperatures, such as in a fire.
* The top opening will serve as a fresh-air inlet. Make-up air should be supplied to the fresh-air inlet through piping similar to that used for the exhaust.
* The total run of vent piping should not exceed 25 ft in length.
* Do not manifold vent piping from multiple units.
* The fan used to ventilate the unit must be rated intrinsically safe.
The cabinets are not required to be grounded. Many manufacturers provide a grounding screw on their cabinet as a convenience for the user. The user can connect this screw to a building ground and use the cabinet-mounted ground point as needed to do the transfer of flammable liquids.
A maximum quantity of 500 liters of flammable and combustible liquid may be stored in an approved flammable liquid cabinet, of which not more than 250 liters may be Class I liquids.
The fire code allows storing up to three cabinet in a fire compartment. A fire compartment is an enclosed space in a building that is separated from all other parts of the building by enclosed construction that provides a fire separation having a required fire-resistance rating.
In industrial occupancies, quantities of flammable liquids and combustible liquids greater than those specified above are permitted in a single fire compartment, where:
(a) the total quantity stored in a group of cabinet is not more than the quantity permitted for three units, and (b) the distance between groups of cabinet described in Clause (a) is not less than 30 m.
To properly assess the situation and consider flammable liquid safety, one must understand the boundaries of a particular fire compartment and consider all flammable and combustible liquids present there. They shall not exceed the maximum quantities.
The best way to identify the boundaries of a fire compartment is to review the architectural drawings of the facility. They would identify fire separations having a fire-resistance rating.
Ensuring Safety in Handling and Storing Flammable Liquids
The intricacies involved in the safe storage of flammable liquids go beyond simply selecting an appropriate container. As vital as it is to have dedicated cabinets designed for such purposes, the environment surrounding them plays an equally critical role. For instance, rooms for storage and dispensing of flammable liquids should be specifically tailored to accommodate the unique needs and challenges presented by these volatile substances. Proper ventilation is paramount, ensuring that fumes don’t accumulate and create a potential hazard.
Furthermore, when considering the dispensing of flammable liquids, the process should be viewed holistically. It’s not merely about transferring a liquid from one vessel to another. It’s about understanding the nature of the substance, the risks involved, and how best to mitigate those risks. Using precise dispensing tools, such as self-closing, leak-proof faucets, can make a substantial difference in safety outcomes.
Lastly, the transfer of flammable liquids, whether from a large container to a smaller one or vice versa, needs meticulous attention to detail. Precautions such as grounding both containers can prevent the dangerous buildup of static electricity, a common ignition source.
In all these procedures, the emphasis should always be on safety first. By understanding the complexities of flammable liquids and respecting the guidelines set for their storage, dispensing, and transfer, we can ensure a safer environment for everyone involved.
Simon Fridlyand, P.Eng., of SAFE Engineering Inc., specializes in industrial health and safety concerns and PSR compliance. For more information, visit www.safeengineering.ca.
