The restricted use of Chlorofluorocarbon (CFC) and hydrochlorofluorocarbon (HCFC) gases within refrigeration and air conditioning system has caused an increased usage of ammonia. Using ammonia avoids the strong greenhouse effect which are prevalent with CFC and HCFC. However, this causes another issue most of the food that we consume will have spent time stored in chilled areas using ammonia.
Whilst in dry conditions, ammonia is lighter than air, but when exposed to wet of humid conditions ammonia can form a vapour, which is heavier than air, causing it to behave differently to the dry gas form.
Ammonia gas will cause irritation of the eyes and cause mucous membranes to develop after a short exposure to levels of 200 part per million (ppm). Once the exposure level reaches 1500ppm it can be quite harmful and the risk of injury becomes increasingly prevalent above 2500ppm. Between 16-27% (i.e. part per hundred) by volume, it also creates a potential explosive risk.
Understand the danger
Without proper maintenance, catastrophic ammonia leaks from refrigeration systems do occur. Deaths and injuries caused from this happen every year. Serious incidents can be caused when an external force ruptures the pipes. Minor leaks from the shaft seals, pipe flanges or valves, or during maintenance can also happen as well. The risk of any escape will depend on the site and other many factors including the leaks size; the location, ventilation, atmosphere, if the leak presents any explosive risks as well as the toxicity.
How to be safe
Ammonia is known to have a pungent smell and irritation, although it’s not a gas that you can be near or aware of. It is advised that you acquire two gas detection sensors. One for the toxic range and another for the explosive range, as this will prevent any entry into the unsafe environment.
There are many factors that need to be considered when dealing with a leak. If it is a small leak it may only need opening of windows and turning on the ventilation to allow the air to clear. Larger leaks may require evacuation of the area or the whole site with the attendance of emergency services.
It is ideal that any site that is using ammonia must have a clear understanding of the risk factors involved within their site. Procedure need to be in place to handle a system breakdown on different scales, these procedures should be familiar to all appropriate staff.