By Monika Witt, Managing Director Of Th. Witt GMBH, Germany, Eurammon Board Member

In my February 2019 article, I examined the need for sprinkler systems in machinery rooms in the USA and their prohibition in Europe. Afterward, I was contacted by Jeff Shapiro who indicated that Anders Lindborg, an honorary life member of IIAR and expert on ammonia releases, had changed his mind just before he passed away and was no longer arguing against sprinkler systems in machinery rooms. Jeff also provided his article from 2011 that laid out the different perspectives of experts from each side. It is evident that this has been a long-running discussion and has caused some confusion within the industry. This article serves to present both perspectives and illuminate that there are different approaches to refrigeration system and building construction depending on where in the world the system is located.

The reason for examining the differences in regulations concerning the safe operation of refrigeration systems was prompted by an IIAR member and owner of many food-processing plants. The desire was to identify the different requirements for the same refrigeration system in different locations of the world. How can the very same installation be regarded safe in the USA and not being permitted elsewhere? This notion has prompted an effort by the IIAR International committee to identify major differences in regulations to be able to inform such multinational companies of the variances.

In Europe, as in the USA, the operation of a refrigeration system can be subject to different inspectors depending on the area you live in. In Europe, operation is purely a national responsibility and there is no uniform regulation or code of conduct. In Europe EN 378 is the most important regulation for refrigeration. Part 2 is harmonized with all European regulations concerning free trade and addresses the design and installation of refrigeration systems. But other parts, particularly part 4, dealing with the operation, are only recommendations and each country may have additional requirements that need to be considered.

Coming back to the sprinklers, Bernhard Schrempf, chairman of EN378 in Germany, argues that any flammable material in the machinery room is not permitted, and sparks to initiate a fire would not be possible because electrical equipment in the room would automatically be disconnected (except for the explosion-protected ventilation systems) once a sensor indicates more than 30,000 ppm ammonia. Before this, at 500 ppm, the ventilation system kicks in to vent any ammonia that may have collected in the machinery room for whatever reason and a warning must be sent to the permanently occupied control center of the plant. Thus any low ammonia levels from minor leakage would be checked by the maintenance staff before a major incident can occur.

Given the facts that: 1) machinery room walls are built in a fire-resistant way to withstand at least 90 minutes of fire with all openings being sealed with fire-retardant sealant, 2) a ventilation system is in place that is activated by sensors to avoid a flammable concentration is accumulating, and 3) entrance is allowed only for authorized and trained personnel, Bernhard Schrempf concluded that a fire could not develop inside a machinery room and water would do more harm than good.

The European point of view is that in the event of a leak, the ammonia should be confined to the machinery room without introducing unnecessary energy which would cause ammonia liquid to evaporate, making the additional gas volume much more difficult to handle compared to the liquid. Adding water to liquid ammonia would increase the volume (about 170 times) which would increase the risk to people by spreading the ammonia vapor over much larger distances. Keeping the ammonia in its liquid form minimizes the risk. But this presumes that sprinklers would activate simultaneous to a liquid ammonia release, i.e. by rupturing pipework due to fire affecting the support structure.

From the US perspective, because sprinklers are not activated by ammonia, but rather by the heat from a significant fire, an ammonia release would be a secondary concern. Considering that vessels and associated piping are equipped with pressure relief devices, and the evaporation of refrigerant inside the system creates a cooling effect, there is little chance that a fire would cause a liquid release. Further, sprinklers would work to extinguish the fire and simultaneously cool the refrigeration equipment.

Jeff Shapiro explained that the issue of sprinklers is more a function of the overall building/occupancy risk versus the isolated risk of a machinery room itself. In the US, sprinklers tend to be installed in a much higher percentage of buildings than in most other countries because of the US building safety scheme. Much of that is associated with incentives, by which owners are allowed reductions in fire-resistance ratings for walls/floors/structures when sprinklers are installed (the assumption being that sprinklers will slow the growth of or extinguish a fire, reducing the level of dependence on fire-resistive building elements).

These construction cost incentives can go a long way to offset the cost of installing sprinklers, and with insurance discounts and higher assurance of business continuity after a fire within sprinklered properties, the economics and business considerations can be complex. Concerning U.S. machinery rooms, the U.S. codes significantly reduce required fire resistance for walls enclosing machinery rooms, and this extends to ratings for door openings, mechanical ventilation openings, sealing of penetrations in the enclosure walls with expensive fire-rated materials rather than simple “plugging” material, etc. when sprinklers are provided. That stated, there is not a specific requirement for sprinklers in an ammonia machinery room simply because there is ammonia refrigeration equipment within it. The requirement to have sprinklers or not is driven entirely by the building code and the owner’s choice of investment. But as stated before, when sprinklers are provided in a machinery room, fire-rated separation is not required.

Jeff assumed correctly that Europe relies on fire-resistive building elements and less on “active” systems, such as sprinklers. In many European countries, water supply infrastructure is not required by any building codes and is simply not available. Instead of prolific sprinkler requirements, Germany, for example, has sophisticated strategies of fire prevention relying on fire-resistant walls, prohibition of flammable materials, and includes isolating sections of the building with special automatic doors, ventilation systems, and evacuation routes (that can sometimes slow down projects like what occurred at the Berlin airport).

I agree with Jeff’s opinion that there is little reason to further debate or initiate further action on the topic. The risk of a liquid ammonia spill occurring while sprinkler heads are active is very low, as is the risk of a fire occurring in a well-designed and well-maintained machinery room. However, this shows clearly that requirements to install a refrigeration system are sometimes driven less by good refrigeration knowledge than by looking at the overall picture, including an examination of building codes.

A good risk analysis is therefore the key to installing a safe refrigeration system and the risks may be considered differently depending on where the refrigeration system is located based on local habits. I am pretty sure that other differences will come up for the very same reason on other occasions and that we will discover there are good reasons for them.