MEMPHIS, Tenn. (AP) -- Two oil refinery workers and two firefighters were injured Monday when they were exposed to a hazardous substance at a Valero refinery in Memphis, fire officials said.
Firefighters were called to the plant in southeast Memphis on Monday morning, Memphis Fire Department spokesman Wayne Cooke said.
Two workers were injured when a sight glass on a pump unit ruptured, exposing the workers to a mixture of propane and hydrofluoric acid, Cooke said.
Cooke said two firefighters also were exposed to the substance. The pump was located at the plant's alkylation unit, Valero Energy Corp. spokesman Bill Day said in a statement.
A sight glass is a transparent tube or window that allows workers to monitor fluid levels within a tank, pipe, pump or boiler.
One worker was transported to a hospital in critical condition. The other worker and the firefighters were taken to a hospital in non-critical condition.
Day said there was no explosion or fire, and no refinery operations were affected. The refinery has notified regulatory agencies and the accident remains under investigation, Day said.
In March, one worker was killed and two others were injured in a fire at the plant.