Chemical Laboratories and Fume Hoods

OSHA specifies requirements for all employees engaged in the laboratory use of hazardous chemicals. This includes those who remove waste from these areas.

OSHA requires the development of a Chemical Hygiene Plan. A recommended (but not mandatory) plan, prepared by the National Research Council (NRC), is incorporated into Section 1910.1450 of the Code of Federal Regulations (CFR). From a design point of view, the plan should address room and exhaust hood ventilation, waste disposal and spill collection. The NRC plan recommends a minimum general laboratory ventilation rate of four to 12 air changes/hr, if the local exhaust systems, such as laboratory hoods, are used as the primary method of control.

OSHA requires that the hood be equipped with a continuous monitoring device to prove adequate ventilation before its use. Some of my clients require that a vane-activated switch be installed inside an exhaust duct, to visually indicate that air is continually flowing. A manometer is recommended, to determine the actual flow rate of the air being exhausted. The manometer should have a set point corresponding to the proper air flow for the duct, and the manometer must be periodically recalibrated, in accordance with the manufacturers specifications.

The NRC plan recommends an average face velocity of at least 100 linear feet per minute (fpm), with a minimum air flow of 70 fpm at any point. If recognized carcinogens are expected to be used, increase these rates to 150 and 125 fpm, respectively. Each exhaust hood should have its own exhaust duct and separate stack. To protect employees conducting maintenance on the roof, some clients require that the exhaust duct be extended at least seven feet above the roof. I recommend that a heat-detection device be provided in the duct, to deactivate the exhaust blower or fan, if a fire occurs.

In the laboratory, OSHA requires us to provide for the collection and temporary storage of accidental spills. Laboratories should be equipped with protective clothing, such as aprons and face/eye shields, compatible with the required degree of protection for the chemicals being handled. In addition, OSHA requires laboratories to contain an easily accessible eyewash and drench-type safety shower; eye protection and gloves for all persons, including visitors; a suitable fire extinguisher; respiratory protection; a fire alarm; and a telephone (that may have a direct line to the outside, bypassing the main switchboard) for emergency use.

The NRC plan recommends that room lights be left on, even when the laboratory is not at work." To reduce risk, laboratory and facilities personnel should conduct periodic inventories to eliminate chemicals no longer in use, or chemicals that serve similar purposes. The NRC plan recommends that shoes be worn at all times and that sandals, sneakers and perforated shoes not be allowed in the lab.

This is a starting point for companies to use in reviewing their existing operations and preparing future plans for constructing facilities. The health and safety requirements are focused on preserving the well-being of our most valued asset: Our fellow workers. i recommend that your equipment layout plans be reviewed by your in-house safety engineers and/or by an outside consulting engineer who specializes in metal finishing design. In this case, let the consultant earn his or her pay, by reviewing and applying the appropriate regulations to your application.