Staying Safe Around Anhydrous Ammonia Exposure

Industrial refrigeration uses many different types of chemicals and materials to aid in refrigeration.

One of the more popular types of refrigerants used in places such as ice rinks or ice manufacturing plants, is ammonia. More specifically, anhydrous ammonia.

What is anhydrous ammonia?

Anhydrous ammonia tank
Liquid ammonia that is used in refrigeration systems is ammonia gas that has been compressed into a pure liquefied form, known as anhydrous ammonia.

Anhydrous ammonia is one of the most effective refrigerants, however, it is also one of the most dangerous.

Liquid ammonia is a clear fluid that evaporates quickly at room temperature, and a major ammonia spill poses a danger to the workplace because liquid ammonia evaporates quickly when exposed to air, which creates an explosive fire hazard.

How to protect your work environment when using anhydrous ammonia

Workplace safety should always be of the utmost importance when working with industrial refrigeration.

However, it can be difficult to figure out which safety measures to take for each refrigerant.

IRSI is here to help.

Vapour gas detectors & anhydrous ammonia

Anyone with a registered refrigeration plant using ammonia as a refrigerant must have vapour gas detector sensors installed.

  • These will sound the alarm and start the ventilation equipment at vapour concentration levels of no higher than 300 ppm, which is the Immediately Dangerous to Life and Health (IDLH) level.
  • Exposures at IDLH levels are likely to cause death, irreversible and permanent health effects, and/or prevent escaping from the area.

Gas sensors & anhydrous ammonia

When utilizing anhydrous ammonia as your refrigerant, it is also important to consider gas sensors.

  • Gas sensors must be installed in the machinery room, valve group rooms, every closed cold room, and next to the end of any relief lines.
  • The sensors are monitored at the control panel of the machinery room, and are integrated into the control system of the refrigeration plant to limit the consequences and potential disasters of an ammonia leak.


20-80% humidity

Tolerated humidity



50% humidity

Short response time

Sensitive to other gases


Special considerations for gas sensors:

  • Room geometry air flow
  • Most probable leak position
  • No unmonitored “pockets” should remain
  • Cold ammonia vapour can accumulate at floor level

Common issues & how IRSI can help

As with any system, issues are common, but with regular maintenance they can be kept in working order by correct placement and correct setting at action limits.

  • One of the problems associated with using gas sensors are false alarms due to things like humidity and exhaust gases.
  • Repeated false alarms must not lead to the shut-off of the gas alarm system. If this happens, contact our IRSI 24/7 emergency service immediately.
  • Refrigeration units must be check on an annual basis to ensure correct calibration and functioning.

Our trained technicians can help you identify the conditions capable of damaging the sensor, and recommend how to eliminate with different compensations and preconditioning.

Want to do some minor improvements to your system? Download our FREE guide on the top 10 ways to improve your industrial refrigeration’s efficiency.

Are you taking care of your anhydrous ammonia system?

Contact us today to ensure your refrigeration system is being properly cared for, and schedule your routine maintenance.