As a business owner or facility manager, the safety of your people, property, and product is one of your most important focuses. It’s important to stay up to date on the latest standards, as non-compliances can bring devastating results. The International Institute of Ammonia Refrigeration (IIAR) standards set the industry standard and are a must-have technical resource to ensure a safe and efficient industrial refrigeration operating environment. IIAR 9-2020 was officially released in 2021 and requires businesses to evaluate their ammonia refrigeration systems to determine if the system meets minimum safety requirements.


ANSI/IIAR 9-2020 provides the minimum safety requirements for existing closed-circuit ammonia refrigeration systems as well as provides a method to determine if existing stationary closed-circuit refrigeration systems using ammonia as a refrigerant comply with minimum system safety requirements.

Before this new standard, it was difficult to apply these standards for the minimum system safety requirements as these standards continued to change over the years. Facility managers questioned if their system fit the updated standard depending on how the system was designed if older code was used, and if the system continued to be maintained, inspected, tested, and in safe operation.

The answer is now clear. This standard provides a method to determine if your existing ammonia refrigeration system complies with minimum system safety requirements or if modifications to the existing system are needed.


The IIAR 9-2020 Standard details specific requirements that facilities need to meet. It’s up to facility owners to understand these requirements and apply them to their current system, identify gaps, and put a plan in place to mitigate those issues.

The new standard also requires an initial safety evaluation to be conducted for each ammonia refrigeration system to ensure compliance with the safety requirement specified in IIAR 9 within five years from the date of publication of this new standard (IIAR 9-2020 was published in March 2021). If this is not done and OSHA or EPA audits the facility and they are not following general industry standards, they could be cited.


Inspecting an industrial ammonia refrigeration system PSM requirements continue to evolve, and it is the responsibility of each facility to ensure it remains compliant. Our PSM experts can perform a system safety evaluation and help verify what requirements are met or not met. The PSM team looks at the safety systems in the ammonia engine room such as ammonia detection and alarms, emergency ventilation, pressure relief protection, machinery room access, and egress. The team also reviews the operating procedures developed for the ammonia refrigeration system and the required inspection, testing, and maintenance practices established based on the ammonia refrigeration equipment in your system. The thorough review examines systems with questions like the following:

  • Are directions provided for the emergency shutdown of the system at a location that is readily accessible to trained refrigeration system staff and trained emergency responders?
  • Does the ammonia alarm activate an alarm to a monitored location so an immediate response can be set in place at a detected concentration of no higher than 50 ppm (can be set to activate at a lower ppm)?
  • Is the machinery room separated from the remainder of the building by tight-fitting construction?
  • Does the machinery room have makeup air provided to replace air being exhausted?
  • Do the compressors shut down if a high ammonia liquid level is detected in a vessel where the compressor suction line is directly connected to that vessel?

Many of the questions asked in the IIAR 9 evaluation are similar to information reviewed during a Process Hazard Analysis (PHA) revalidation which is required at least every 5 years.  During your next PHA revalidation, you may also consider performing this new required IIAR 9 Minimum System Safety Evaluation.

After our PSM team performs the IIAR 9 evaluation and identifies any gaps, Bassett Mechanical’s team of designers, engineers, and technicians work together to offer full-service solutions for complete system care. Our team will help bring you peace of mind and bring your facility into compliance.


Developing trusted relationships with a mechanical contractor with PSM capabilities is key to knowing your building inside and out in a way that will help you to conserve the integrity of the building and your business. Lighten the burden on your business by providing the necessary support to verify that your facility is safe for all employees and surrounding communities.

With Bassett Mechanical’s expertise in industrial ammonia refrigeration and other natural refrigerants, our PSM service offerings help your organization develop a safe work environment that will protect your brand, provide regulatory compliance, and create peace of mind.