Machinery Rooms in Europe and USA: Sprinkler Systems


Machinery rooms are enclosed zones with mechanical ventilation, separated from public space and accessible only to authorized personnel. They serve primarily as dry and protected places for the components of a refrigeration system, mainly compressors and pressure vessels, but also additional equipment, for example in secondary systems the evaporator and/or water cooled condensers.

The machinery room ensures that only authorized personnel, familiar with the characteristics of refrigeration systems, can be in contact with the equipment containing ammonia. Taking a look at the entire refrigeration system we can certainly all agree that the chance for an ammonia leak is nowhere greater than in the machinery room, since the high pressure is created here and most of the liquid is stored here. The machinery room is usually the place where most maintenance takes place and this increases the chance for potential accidents.

It makes therefore sense to use utmost care when designing, installing and maintaining the equipment in the machinery room.

It makes therefore sense to use utmost care when designing, installing and maintaining the equipment in the machinery room.

I do not want to get into details where the regulations differ slightly, but would like to bring up one issue that is handled quite differently on both sides of the pond, namely the requirement for sprinkler systems in the machinery room. In USA sprinkler systems are mandatory, whereas in Europe it is more or less prohibited to use them except under certain pre-conditions (EN378-3. section.

One of the persons in strong opposition to sprinkler system was the wellknown Anders Lindborg, an honorary life member of IIAR.

The reason for prohibiting sprinklers from 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, as the gas volume is much more difficult to handle compared to the liquid. Adding water to liquid ammonia would introduce energy and evaporate the ammonia resulting in an enormous increase of volume (about 170 times) which increases the risk to people and spreads the ammonia vapour over much larger distances.

Keeping the ammonia in its liquid form minimizes the risk. According to German official bodies (i.e. Mr. Köritz) sprinkler systems do not belong in machinery rooms. (In order to wash down 1l ammonia about 30.000 l water would be needed).

It is possible that this requirement has been added since sprinkler lobby intervened because in some countries insurance fees would be higher compared to systems not having a sprinkler system. An older version of EN378 stated that sprinklers were not permitted in machinery rooms. The latest version, after vigorous lobbying from certain quarters, states that sprinklers are required but only if they meet certain restrictions, namely that

  • The sprinkler heads are individually activated by high temperature (> 141°C)
  • There is no manual override of the system
  • The system conforms to the European Standard requirements

Something to think about….