ANSI/IIAR 2-2014 - What Does It Mean for the Ammonia Refrigeration Industry

As many of us were informed today, the new standard for safety in Industrial Ammonia systems, ANSI/IIAR 2-2014 is now available for purchase and use from the IIAR, the International Institute of Ammonia Refrigeration.  This standard represents a substantial number of changes over the previous version, 2008 Addendum B.

As a member of the Standards Committee, and having spent countless hours in both in-committee work on the standard and reviewing it during public review periods (many of the public comments were mine) I have a great appreciation for both the excellent information and guidance it contains, and for the increase in complexity it introduces into the design of industrial ammonia systems.  The normative portion of the standard has almost doubled, from 36 pages (not including normative Appendices) to approximately 64 pages (I haven't received a copy of the final published standard at the time of writing, but have a late public review draft).  The overall length of the standard plus Appendices has also nearly doubled.  This represents a substantial increase in guidance to the average user, but also a substantial increase in requirements to which systems must be designed.

While I've spent a lot of time with the standard, and know it quite well, I don't plan on designing systems without having a copy handy.  I thought that, given the news it's become available, this might be a good opportunity to give some highlights regarding important changes.  Whether you agree with the changes, think they're unnecessary, or think they haven't gone far enough, the standard has been accepted by ANSI and will undoubtedly be referenced by engineering specification writers and, likely, code bodies in the coming years.  I would encourage everyone in the industry to read the standard in its entirety, become involved in its continuing maintenance by requesting interpretations, and submitting public comments when the standard is updated (around 2019 or so).

In the meantime, here are a few notable changes you can expect from the new standard.  These are by no means all of the changes, and again, you should read it and become familiar with all of its provisions.  And of course, Sterling Andrews Engineering is here to help you with ensuring your new or modified system design complies.

1. Emergency ventilation - The old version of the standard required 30 ACH for emergency ventilation.  While this has not changed, the indirect requirement for multiple fans has been removed.  Previously, a minimum of (2) fans providing 20 ACH each or (3) fans of 10 ACH each were required to ensure that the failure of a fan did not cause the emergency ventilation rate to drop below 20 ACH.  This requirement has been removed.  While the reasoning can be debated, the fact is that standard now allows a single fan to be provided for emergency ventilation.  It does not provide any increased quality measures for the fan to compensate for this, and so designs with a single emergency fan should be scrutinized to ensure that the fan will be available when needed.  While certain items, like relief valves, are not required to be redundant, such safety items are manufactured and tested to a very high quality standard.  Items such as pressure switches, fans, and other safeties do not have such requirements in-place, so redundancy is another means by which functional safety can (and should) be increased. 

2. Ammonia Equipment in Areas Other Than Machine Rooms - The standard now has language to attempt to accommodate equipment such as vessels and pumps outside of machinery rooms.  These were largely prohibited in earlier versions of IIAR 2 and ASHRAE 15.  However, additional, sometimes complex rules are provided in conjunction with such installations, and careful study of the standard for your particular situation is necessary.

3. Ammonia Detection - Although it has essentially been required by ASHRAE 15 for many years due to the low concentration limits for Ammonia, the new version of IIAR 2 now requires ammonia detectors in all refrigerated rooms in addition to the ammonia machine room.

4. System Design Pressures - The new version of the standard has increased requirements for system design pressures.  While the consequences for expansion to existing systems are still not well-understood, the standard attempts to shield existing systems from some of the possible effects.  The most significant change is that system low-sides are now required to be designed to 250 psig.  While this has very little impact on new systems, existing systems may run into problems depending on how they were designed.  The exemption listed in the standard only applies where process conditions (ammonia pressure and temperature, essentially) remain the same as those for which the system was originally designed.  This is often not the case for ammonia systems in operation for many years.  Equipment and piping design pressures and temperatures should be given special scrutiny.

5. Emergency Pressure Control - While emergency pressure controls are still required in model codes, the new version of IIAR 2 has moved these to an informative appendix.  The effect is essentially nullified, in that most if not all systems will still be required to have these controls.

This list represents just a fraction of the new and updated content in the standard.  Again, we recommend that Engineers, Contractors, and End Users obtain copies of the updated standard and become familiar with the content.  Sterling Andrews Engineering will continue to be your resource for support and guidance with this and other updated standards as they become available.

If you have a question or comment, feel free to leave them here on the blog or to contact us.