By John R. Hall
Refrigeration contractors know that there are several upsides to ammonia refrigerants. The most common is its compatibility with the environment. Ammonia does not contribute to global warming because it does not deplete the ozone layer. It has thermodynamic qualities that require less electricity in its usage. And ammonia has a distinct odor, which is a safety valve when trying to detect leaks in a system.
Ammonia refrigerant also has many applications, such as use in industrial facilities like meat, poultry, and fish processing plants, dairy and ice cream plants, wineries and breweries, soft drink processing facilities, and cold storage warehouses.
When handled properly, ammonia refrigerants are very friendly, efficient, and versatile. But, like many other chemicals, ammonia must be handled with care. If it is not, it can have health consequences for the technician and others. Ammonia is labeled as a high health hazard because it is corrosive to the skin, eyes, and lungs. According to the Occupational Safety and Health Administration (OSHA), “Exposure to 300 ppm is immediately dangerous to life and health. Ammonia is also flammable at concentrations of approximately 15 to 28 percent by volume in air. When mixed with lubricating oils, its flammable concentration range is increased. It can explode if released in an enclosed space with a source of ignition present, or if a vessel containing anhydrous ammonia is exposed to fire.”
OSHA also states that “accidental releases of ammonia from refrigeration facilities have resulted in both injuries and deaths to employees of these facilities. These injuries and deaths are caused from contact with both liquid and vapor forms of ammonia. Because refrigeration systems operate at elevated pressures, additional care must be taken to maintain and operate these systems so as to prevent releases with potentially catastrophic consequences.”
Three Common Mistakes
One refrigeration contractor, Charles Ruebensaal of Tempest Inc., Cleveland, recently polled his six start-up and service technicians about the most common mistakes when working with ammonia. Each person has experience in servicing both ammonia and Freon industrial systems.
“I put the question out to each of them to get a response,” Ruebensaal said. “The following are the three most common responses.
“First mistake, a failure to use the correct personal protective equipment (PPE), specifically eye protection. When performing maintenance or repair work that doesn’t require a full face respirator or escape mask, wearing proper eye and face protection is a must. This is a common mistake made when draining oil.
“Secondly, a lack of pre-planning. Take your time, plan out your task, and control the hazards. Lock out/tag out electrical, tag all isolation valves that are required to be closed to isolate the repair, and provide a safe location to purge the component. Be sure ammonia is not trapped in the piping and everything is purged out before opening up the component for repair.
“Thirdly, not knowing how to keep vapors from endangering others. This is especially true when making a repair to the ammonia system on the roof of the building — either at the evaporative condensers, or at a control valve station group. It is important to locate any make-up air intakes for the plant before beginning your work. Make sure these are turned off or blocked off. Although the ammonia vapor should rise and not cause problems, prevailing winds and down drafts can cause ammonia vapor to be drawn into the building to levels strong enough to cause alarm or evacuation.”
The Agency for Toxic Substances and Disease Registry has a website that discusses ammonia and its impact on public health. Visitwww.atsdr.cdc.gov/toxfaqs/tf.asp.
Publication date: 01/09/2012