Chilling With Ammonia

Concerning the Government Concentrate “Propane Is Hazardous in Air Conditioners,” why not reintroduce ammonia as a refrigerant gas for small-sized refrigerating equipment to get rid of bureaucratic market control (C&EN, July 8, page 21)?

Ammonia was used in household refrigerators until 60 years ago in the form of easy-to-build and safe-to-use ammonia absorption devices. They were practical, even if not the most energy efficient. With advances in magnet technology, small, hermetically sealed, and energy-efficient direct-vapor-cycle ammonia refrigerating units can be built. The electrical parts of the motor are not in contact with the corrosive liquid ammonia inside the circuit.

The total quantity of ammonia in the refrigerating unit would be in the harmless range—on the order of what can be purchased as 10% ammonia solution in any drugstore. Ammonia gas is not very flammable and does not form explosive mixtures with air. A leakage of the circuit would be immediately detectable by smell, and ammonia is a natural environmental constituent.

Edgar Müller
Prilly, Switzerland