by Eric Smith, P.E., LEED AP, IIAR Technical Director

Alarms and Detectors

The topic of alarms and detectors is often discussed in this publication and several others. Perhaps the reason that it is discussed so much is that there is not clear, written, single source guidance on how to handle the various aspects surrounding ammonia alarms and detectors. As part of a major revision of IIAR Standard 2, the IIAR will be attempting to provide clearer guidance and we request the assistance of IIAR members. As is done with many controversial or difficult issues, IIAR will be conducting a panel session at the annual conference to get feedback from the audience. If you have an interest in this important topic, please plan to attend the final session on Wednesday, March 20. The panelists will be industry experts who deal with codes, emergency response, design and maintenance. Note that this panel will focus on the use of alarms and detectors, and not the technology or selection of them. To support this effort, we ask that you consider the following aspects, and come prepared with questions, suggestions, and anecdotes.

Among a litany of questions that likely surround alarms and detectors are:

What are the minimum code requirements? Oddly, this is not made clear enough in existing documents, and people have different views on what is written. For many years, it has been perceived that the only definite requirement is to have one detector – located in the machinery room. However, ASHRAE 15 exceptions on charge limits for industrial occupancy would indicate otherwise. Further, the latest edition of IIAR 2 requires at least two detectors, set at different concentrations. There are also new code body proposals that could require detector/alarm systems be approved by authorities having jurisdiction. What might this approval entail? Would it be applicable to existing facilities? What if a facility wanted to add a detector? Would this require re-approval? There are also proposals that ammonia detectors be “listed” by nationally recognized testing agencies (such as UL). Is this necessary or will it simply raise the costs of detectors and provide no additional level of surety? Is the industry ready for such a change?

Should relief vent lines be required to have ammonia detection? What should be done if a vent line detector is activated? Naturally, the concentration of ammonia in a relief header will be high, but this is not a good indicator of whether there is a serious problem, or a short term relief valve “puff.”

Should every storage or production room have a detector and/ or alarm? If an interstitial space has ammonia equipment, but is not normally occupied, should the space be treated differently?

Should concentration levels, as indicated by detectors, initiate different responses? For example, a 25 ppm concentration level is common when service work is being performed. But if no work is being done and this concentration is reached, should employees leave the area? Or should levels be as high as 300 ppm before employees leave? Can two different alarms be used for different action levels? Does this expect too much from employees?

What are the mechanisms that could distinguish small releases that occur during maintenance and unintended, unpredicted releases? Is there, or should there be a difference if a release occurs in a machinery room versus an occupied storage room or production room?

Should ammonia detection systems be tied to the fire alarm panel? Although this seems to be common, it also can be problematic if fire companies show up expecting a fire, but are unprepared for an ammonia release. Another problem is that they might show up for a minor release due to maintenance. Related: shall notification of detection be facility-wide or only to a designated monitor?

Should back up power be required for alarm/detection systems?

What color should ammonia alarms be? Should this be distinct and defined? One user has complained that local officials wanted a unique color, but would not say what it should be. In any case, red is an indicator of fire. And fire evacuations can be treated differently than ammonia release evacuations.

How do employees know if they should evacuate or shelter in place? Should detector/alarm systems be integral in this decision? Is a public address (PA) system adequate for this? Is it possible or reasonable that a PA system be tied to the ammonia detection system?

Should there be more definitive guidance within standards on the placement of detectors? For example, ammonia released in very low temperature rooms or freeze tunnels behaves differently than in higher temperature rooms.

Is it ever appropriate to over-ride detectors if daily routines such as high humidity clean up shifts create false positives? Is it appropriate to over-ride detectors if maintenance is being performed? Is there an acceptable compromise?

How extensive should additional functions of the refrigerant detection system be? For example, shall they be used for automatic equipment shut down? Does reliance on detection/alarm systems create a false sense of security? In other words, will the presence of this equipment make people believe that risks are reduced? What is expected by OSHA and the EPA? Is this beyond the minimum requirements? What are the financial implications of more detectors and alarms in initial and ongoing costs?

And perhaps most importantly, how far should IIAR go in establishing guidance to answer these questions? When consider this, we must bear in mind the adage “If we don’t establish guidelines ourselves, someone else will do it for us.”