Other Ventilation Systems
- If other local exhaust systems are used in the laboratory, they should be designed by a ventilation engineer.
- Do not attach canopy hoods, flammable storage cabinet exhausts, or snorkel systems to existing fume hood exhaust ducts without consulting a ventilation engineer.
- Glove boxes generally operate under negative pressure, though some operate under positive pressure in which case leaks could cause problems. Positive pressure glove boxes should be thoroughly tested before each use and there should be a method of monitoring the integrity of the system (such as a shutoff valve or a pressure gauge designed into it).
- Isolation rooms or clean rooms typically operate under negative pressure and require considerable engineering. Procedures for entering and exiting these areas should be written out and employees should be trained accordingly.
- Environmental rooms, either as refrigeration cold rooms or as warm rooms for growth or organisms and cells are usually closed air-circulation systems, thus the release of hazardous chemicals in these areas poses potential dangers.
Refrigerant Leaks: Since release of refrigerant chemicals in such an enclosed area may cause asphyxia, it is recommended that direct reading monitor(s) tied to an alarm system be installed to warn personnel of potentially hazardous exposures prior to entering the room. If direct reading monitors have not been installed in the area, it is recommended that warning signs be posted on entrances and hand-held direct reading monitor(s) for refrigerant gases be provided prior to accessing the room. In the interim, if alarms are not installed and hand-held direct reading monitors are not available, procedures should be put in place to inform supervisor prior to accessing these enclosures (i.e. location, time of entry, approximate time of departure, etc.). List any special instruction in Section III.C.4 Site Specific Ventilation Information.
- Magnetic latches or breakaway handles on doors of environmental rooms should be installed to allow a trapped person to open the door(s).
- The electrical system within environmental rooms should be independent of the main power supply so that persons are never left in these areas without light.
- Volatile flammable solvents should not be used in cold rooms due to fire hazards from ignition sources. For additional information, see Section III.F.3 Laboratory Equipment, Refrigerators and Freezers.
- The use of volatile acids should be avoided in cold rooms because such acids can corrode the cooling coils in the refrigeration system, which can lead to the development of leaks of hazardous refrigerants.
- Hazardous chemicals should be stored in cabinets fitted with auxiliary local ventilation.
- Laboratory apparatus that may discharge hazardous vapors (vacuum pumps, gas chromatographs, liquid chromatographs, and distillation columns) should be vented to an auxiliary local exhaust canopy or a snorkel system.