Proper room ventilation with adequate air exchanges will eliminate most unsafe chemical vapors. The only time you may want to ventilate a chemical storage cabinet is if the ventilation in the laboratory or chemical stores area is inadequate or you are required to provide cabinet ventilation because of state or local law.

Venting a chemical storage cabinet is not necessary for fire protection. In fact, a vented cabinet could compromise the ability of the cabinet to protect its contents from a fire. During a fire, vapor from the hazardous chemicals in the cabinet may be released. If the integrity of the chemical storage cabinet is compromised because of the ventilation system, these hazardous fumes will escape from the cabinet and a very dangerous and devastating situation may occur.

Below are the proper guidelines established by the National Fire Protection Association for the ventilation of flammable chemicals.

National Fire Protection Association NFPA #30, 4-3.2

The cabinet is not required to be vented for fire protection purposes, however, the following shall apply:
(a) If the cabinet is vented for whatever reasons, the cabinet shall be vented outdoors in such a manner that will not compromise the specified performance of the cabinet, as acceptable to the authority having jurisdiction.

(b) If the cabinet is not vented, the vent openings shall be sealed with the bungs supplied with the cabinet or with bungs specified by the manufacturer of the cabinet.

A-4-3.2 Venting of storage cabinets has not been demonstrated to be necessary for fire protection purposes. Additionally, venting a cabinet could compromise the ability of the cabinet to adequately protect its contents from involvement in a fire since cabinets are not generally tested with any venting. Therefore, venting of storage cabinets is not recommended.”

Vent openings are often provided by manufacturers because some jurisdictions mandate that the cabinet be vented to prevent vapor accumulation in the cabinet and because some users desire this feature if the cabinet will be used for toxic or noxious materials. It should be understood that venting the cabinet may defeat its fire integrity. If it is not necessary or required that the cabinet be vented, then the vent openings should be kept tightly capped with the metal bungs provided for that purpose. If the cabinet must be vented, then these procedures should be followed:
  • Remove both metal bungs and replace with flash arrestor screens (normally provided with cabinets). The top openings will serve as the fresh air inlet.
  • Connect the bottom opening to an exhaust fan by a substantial metal tubing having an inside diameter no smaller than the vent. The tubing should be rigid steel.
  • The fan should have a non-sparking fan blade and non-sparking shroud. It should exhaust directly outside.
  • The total run of exhaust duct should not exceed 25 feet.