Dipping Operations - Exhaust Air & Cyanide

OSHA standards regarding exhaust air protect employees against fire and explosion hazards that can result from the accumulation of flammable vapors and from dangerous levels of toxic air contaminants. Cyanide receives special attention in OSHA regulations because all cyanide compounds are highly toxic and a relatively small amount can be lethal.

Exhaust Air

Exhaust air cannot be recirculated when any substance in the air poses a health hazard to employees or exceeds 25 percent of its LFL.

Any recirculated exhaust air from a dipping or coating operation using flammable liquids or liquids with flashpoints greater than 199.4°F must be free of any solid particles that pose a health or safety hazard for employees. Exhaust air must be monitored by approved equipment, such as alarm systems that automatically shut down the operation when the vapor concentration for any substance in the exhaust airstream exceeds 25 percent of its LFL.

Exhaust hoods may be used to assist with dip tank ventilation as long as OSHA regulations are satisfied, as follow:

• Each room with an exhaust hood has a volume of outside air that is at least 90 percent of the volume of the exhaust air.
• The outside air supply does not damage the exhaust hoods.

Cyanide

If a dip tank is filled with cyanide, the dip tank must have a dike or other safeguard to prevent cyanide from mixing with an acid should the tank fail.

To learn more about Dipping, Coating & Cleaning Operations visit our Dipping, Coating & Cleaning Operations Online Training web page.