The publication of ANSI/IIAR 2-2008 (Addendum A), American National Standard for Equipment, Design and Installation of Closed-Circuit Ammonia Mechanical Refrigerating Systems, was released by the International Institute of Ammonia Refrigeration, Alexandria, Va. According to the organization, the publication includes several important changes to the previously released edition of ANSI/IIAR 2-2008.

According to IIAR, the need for an addendum arose during the 2008 standards renewal process as deliberation began on the topic of machinery room design. It was at that time that IIAR committed to establishing an updated standard that would address the concerns and needs of the industry surrounding machinery room design.

The major alterations outlined in Addendum A pertain to emergency switches, room pressure, signage and more. Continuous ventilation is no longer a requirement, and the formulas used to determine "normal" and "emergency" ventilation rates have been changed.

IIAR says the change to the continuous ventilation requirement is consistent with the NEC (which both ASHRAE and IIAR reference), requiring ammonia detection if electrical machinery is not Class I, Division 2. Regarding normal ventilation, the new formula is based on: a rate of 20 air changes per hour, or the quantity of air needed to limit the room temperature to 104°F (40°C) based on the heat load, whichever value is higher.

Under the new standard, normal ventilation fans need not run continuously or at full speed except when refrigerant is detected, and emergency ventilation is based on 30 air changes per hour.

The new edition of ANSI/IIAR 2 is available online to IIAR members in the eLibrary, or it may be purchased from the organization’s online store.