Understanding What Belongs on Your Ammonia Refrigeration Machinery Room Placard Under the Latest IIAR Standards | Blog No. 102

As the industrial refrigeration industry continues to evolve, so do the standards that govern safe system operation and emergency response. One question that continues to surface among facility owners, engineers, and contractors is whether Field Test Pressure must be included on a machinery room placard. Recent updates to IIAR standards have brought clarity to this topic—and also corrected common misconceptions.

At Macha PSM, our engineering team frequently receives requests for guidance on what information should (and should not) appear on placards. A recent inquiry from a partner facility inspired us to highlight the latest requirements so operators can remain compliant and avoid unintentionally posting inaccurate system information.

Field Test Pressure: No Longer a Required Placard Item

Under legacy practices, some facilities routinely included field test pressure on machinery room signage. However, current IIAR standards no longer require this information, and in some cases, posting it can be misleading or technically improper—especially if the value is assumed rather than verified through testing.

Both IIAR 9-2021 Addendum A-2024 and IIAR 2-2021 clarify the expectations for signage, and field test pressure is not part of the required placard content for systems built before or after 2021. Instead, the standards emphasize accuracy, hazard communication, and emergency usefulness—areas where assumptions or incorrect values can create risks rather than reduce them.

What the Standards Do Require

IIAR 9-2021 Addendum A-2024 – Section 7.2.9.1

Facilities must ensure the following signage is provided in machinery rooms:

• NFPA 704 placards

• Alarm signage, identifying the meaning of each alarm

• Restricted access signage, indicating that only authorized personnel may enter

This section focuses on hazard visibility and access control—not technical system parameters.

IIAR 2-2021 – Section 5.14.1.1

For systems containing more than 22 lbs. of ammonia, IIAR requires signage or schematic drawings that include:

1. Emergency shutdown instructions

2. Emergency contact information

3. Maximum intended ammonia inventory

4. Refrigerant compressor oil type

5. Low-side and high-side design pressures

These design pressures are tied to the lowest MAWP (Maximum Allowable Working Pressure) on each side of the system—not the field test pressure.

This is a key distinction: Design pressures are required. Field test pressure is not.

IIAR 2-2021 – Section 6.15

Additional required signage includes:

• NFPA 704 placards at all machinery room entrances

• Alarm signage in accordance with Section 17.6

• Restricted access signage

• Emergency control switch signage

• Electrical hazard signage when applicable

The emphasis remains on safety communication and emergency readiness.

Why Field Test Pressure Should Not Be Included

Placing a field test pressure on a placard can create more harm than good if:

• The value is assumed or outdated

• The system has changed for initial testing

• Personnel interpret it as a design or operating limit

Because field test pressure is not part of the IIAR-required placard information—and in some cases can mislead emergency responders or operators—facilities should refrain from adding it unless absolutely certain of its accuracy and necessity.

What Should Be Included Instead

Facilities should focus on ensuring their placards and schematics include the correct design pressures, based on:

• The lowest MAWP on the low side

• The lowest MAWP on the high side

These values are meaningful for equipment protection, emergency planning, and regulatory compliance. Most importantly, they align directly with IIAR’s current requirements.

Final Thoughts

As standards continue to evolve, accurate and compliant signage plays a crucial role in maintaining a safe ammonia refrigeration environment. Understanding the difference between historical practices and modern requirements is essential—especially when facilities rely on this information during emergencies.

If your facility needs assistance determining compliant design pressures, evaluating existing signage, or updating your PSM documentation, the experts at Macha PSM are here to help.

Thank you for Reading!

Previous Blog: Highlighting a Powerful Training Opportunity: Ammonia Awareness Through PSM Academy | Blog No. 101

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