Used in laboratories beginning at the university level, perchloric acid is a powerful oxidizing agent that may react explosively in laboratory ventilation systems.  Perchloric acid reacts with alcohols and certain organics to form very unstable (to shock or heat) perchlorate esters, which have the same shattering power as nitroglycerin.  These crystalline esters build up in fume hoods & ducts and explode violently when disturbed.

Because of this, it is important that no one should attempt maintenance on or cleaning of hoods and exhaust systems until safe working conditions are assured.

If a laboratory hood has been exposed to heated perchloric acid, tests must be conducted to determine if explosive perchlorates have formed on the hood walls and duct system.  This must be completed before any inspection, cleaning, maintenance, demolition, or any other work is done on any part of the hood interior or exhaust system.

At ACM Services, Inc. we have the experience, the tools, and the trained professionals to safely test and clean your exhaust system.  We can also dismantle and properly dispose of contaminated hood, duct, and fan components.

Dismantling or performing maintenance on a laboratory exhaust system contaminated with shock-sensitive perchlorates is a hazardous operation.  Let the professionals at ACM Services, Inc. safely and economically handle your project.

Get more information on getting acid off hoods from the Oak Ridge National Laboratory.

Some accidents involving perchloric acid:

• A violent explosion took place in an exhaust duct from a laboratory hood which blew out the windows, bulged the exterior walls, lifted the roof, and extensively damaged equipment and supplies.  Sometime prior to the explosion, the hood had been used for the analysis of miscellaneous materials.  The explosion apparently originated in deposits of perchloric acid and organic material in the hood and duct.
• During routine maintenance involving partial dismantling of the exhaust fan on a ventilating system, a detonation followed a light blow with a hammer on a chisel held against the fan near the seal between the rear cover plate and the fan casing.  The intensity of the explosion was such that it was heard four miles away.  Of the three employees in the vicinity, one sustained face lacerations and slight eye injury; the second suffered loss of four fingers and possible loss of sight in one eye and the third was fatally injured when the 6-inch chisel penetrated his skull.
• A stone table of a fume hood was patched with glycerin cement, and several years later, when the hood was being removed, the table exploded when a worker struck the stone with a chisel.  The hood had been used for digestions with perchloric acid.
• A chemist was drying alcohol off a small anode over a Bunsen burner in a hood used for tests involving perchloric acid.  An explosion tore the exhaust duct from the hood, bent a portion of the ductwork near the fan, and blew out many windowpanes.