Machinery Room Ventilation System Tests

Machinery room ventilation systems have long been required by model codes and standards. Dating back to at least the 1967 Uniform Mechanical Code[1], refrigeration machinery rooms have been required to be configured with adequate ventilation in the event of a refrigerant release. While we have written previously about the current ventilation design, control, and testing requirements in ANSI/IIAR 2-2021, it is important to expand our consideration regarding the requirements for testing a machinery room ventilation system. 

With the release of ANSI/IIAR 6 in 2019, the ammonia industry now has clear requirements regarding inspecting, testing, and maintaining (ITM) emergency ventilation systems. Table 12.1 in the standard lists each of the ITM requirements for emergency ventilation systems, and the frequency for each.

Table 12.1

Emergency Ventilation Systems Inspection, Testing, and Maintenance Tasks

ITM Task Description	Frequency
Inspection
a) Verify automatic function of Temperature Control Ventilation	WA-A
b) Visually inspect ventilation equipment for damage and degradation	S
c) Observe for indications of excessive vibration in powered supply and exhaust ventilators	S
d) Listen for abnormal sounds	S
e) Visually inspect fan belt tension and condition	WA-S
f) Visually inspect emergency ventilation override switch for damage or degradation	S
g) Visually inspect emergency ventilation control switch for proper installation of signage	S
Testing
a) Functionally test audible and visual annunciators	A
b) Functionally test manual override of Emergency Ventilation	A
c) Expose ammonia detector(s) to calibration test gas and verify function of ventilation equipment	A
d) Test sail switches, air flow sensors, or other means to verify function of emergency exhaust equipment	A
e) Test function of intake louvers	A
f) Verify fan belt tension is adequate by measurement	WA-A
g) Functionally test notification to a monitored location for the loss of power to or failure of the emergency ventilation system	A
Maintenance
a) Lubricate exhaust fan components	WA-M
b) Replace fan belts	WA-5

Frequencies: S – Semiannual, A – Annual, WA – Where Applicable, 5 – Five Years

Inspection

Annual inspection tasks include verifying the temperature-controlled ventilation fans are activated automatically (if applicable). 

Semi-annual inspection tasks include checking the ventilation equipment for damage, excessive vibration, and abnormal sounds. The fan belt and ventilation control switches should also be inspected for proper tension (fan belt), and labeling on the control switches.

Testing

Each of the testing activities should be performed on an annual basis. These tests include:

• Functionally testing audible and visual annunciators
• Functionally testing the manual override control of the emergency ventilation
• Verifying the ammonia detectors activate the emergency ventilation by exposing them to calibration gas
• Testing sail switches, and airflow sensors
• Measuring the fan belt tension
• Functionally testing that a monitored location is notified if the ventilation system loses power or fails

Maintenance

Only two items are listed in the maintenance section and include lubricating the exhaust fan components on an annual basis, and replacing fan belts every five years.

Airflow Testing

Notice the table above makes no mention of testing the ventilation system airflow. In the past, we have witnessed CalOSHA cite ammonia refrigeration facilities for failure to properly test their machinery room ventilation system. Interestingly, OSHA does not reference the PSM standard or ANSI/IIAR 6-2019 in their citation, but rather the lesser known regulation Title 8 CCR §5143 “General Requirements of Mechanical Ventilation Systems”. Specifically, this regulation requires that:

“The ventilation rate of every mechanical ventilation system used to prevent harmful exposure shall be tested after initial installation, alterations, or maintenance, and at least annually, by means of a pitot traverse of the exhaust duct or equivalent measurements. Records of these tests shall be retained for at least five years.” [Title 8 CCR §5143(a)(5)]

For example, on 10/4/16, OSHA cited a California facility for failure to comply with the above-stated requirement. In the citation notes, OSHA indicated that “the employer did not test the ventilation rate of the mechanical ventilation systems used to prevent harmful exposure of ammonia in North and South machinery rooms. The employer did not provide test records as required.”

Airflow tests can be conducted using an anemometer to measure the velocity of air at the fan discharge. We recommend taking measurements at several locations and averaging the results. Once the air velocity has been determined, the airflow (CFM) can be calculated by multiplying the velocity by the fan discharge area.

Consideration can also be given to performing an additional qualitative test using a smoke candle to subjectively determine if make-up air is adequate and if the room is free from dead spots. These tests can expose ventilation system weakness and can be an effective training tool for employees who work inside a machinery room. As a best practice, we use the smoke test to develop a ventilation system diagram that visually depicts the function of the system.

Ammonia refrigeration facilities in California need to be aware of the requirements of Title 8 CCR §5143. We suggest that annual airflow tests be incorporated into the facility inspection, testing, and maintenance program for other refrigeration equipment onsite. A ventilation test can be readily integrated into other annual tests such as annual inspections, ammonia detection/alarm tests, and e-stop tests.