Ammonia has long been used as a refrigerant for industrial applications. Engineering and maintenance requirements, have proven themselves to cope with its high toxicity and low Flammability. Technical progress extension application for ammonia, for example, low-battery, packaged liquid coolers for use in air conditioning. Ammonia can not be used with copper and copper alloys, refrigerant and components should be of steel or aluminium. This can be a problem for the air-conditioning market, where copper was the main material for pipelines and plant. One property, which is unique for ammonia compared with other refrigerants is that it is less dense than air, so leakage ammonia as a result of rising upwards and into the atmosphere. If the plant is located in the courtyard or on the roof leak of ammonia can retreat without prejudice to the driver and passengers. Ammonia can be detected by a characteristic smell at very low concentrations, and this acts as an early warning signal. Safety aspects of the ammonia plants is well documented, and there is reason to expect that steady growth in the use of ammonia as a refrigerant.