Exhausted Enclosures

A image of a metal exhausted enclosure that has ventilation in a lab.

These are suitable for gases (inert, flammable, oxidizing, reactive, pyrophoric, toxic, highly toxic, or corrosive). They are not designed for cryogenic fluids. These may be suitable for highly toxic solids and liquids in Group H-8 occupancies (prior to 2007). 

Construction. Exhausted enclosures shall be of noncombustible construction. 

Ventilation. Exhausted enclosures shall be provided with an exhaust ventilation system. The ventilation system for exhausted enclosures shall be designed to operate at a negative pressure in relation to the surrounding area. Ventilation system shall be installed in accordance with the California Mechanical Code. Ventilation systems used for highly toxic and toxic gases shall also comply with the following: 

  1. The average ventilation velocity at the face of the enclosure shall be not less than 200 feet per minute (1.02 m/s) with not less than 150 feet per minute (0.76 m/s).
  2. Exhausted enclosures shall be connected to an exhaust system. 
  3. Exhausted enclosures shall not be used as the sole means of exhaust for any room or area. 

Fire-extinguishing system. Exhausted enclosures where flammable materials are used shall be protected by an approved fire-extinguishing system.