R717

R-717 is the refrigerant designation for ammonia (NH3). It is a natural refrigerant widely used in industrial refrigeration and in some large-scale HVAC applications due to its thermodynamic properties and cost effectiveness.

Key properties include a boiling point of −33.34 °C at 1 atm, a critical temperature of about 132.4 °C, and a critical pressure around 113 bar (approximately 11.3 MPa). Ammonia has a high latent heat of vaporization, which contributes to strong refrigerating capacity. It is classified as non-flammable (ASHRAE A1) under normal conditions, but it is highly toxic and irritating at relatively low concentrations. Proper leak detection and ventilation are essential for safety.

Environmentally, R-717 has zero ozone depletion potential and essentially zero direct global warming potential, making it attractive from a climate perspective compared with many synthetic refrigerants. Its use, however, requires stringent safety measures due to toxicity and potential for asphyxiation in enclosed spaces.

Applications and equipment design typically involve large industrial refrigeration systems for food processing, cold storage, beverage production, and ice rinks. Ammonia systems often employ high-efficiency components and may be used in cascade arrangements with other refrigerants (for example, CO2 in certain installations) or in dedicated ammonia circuits for large capacities. Material compatibility, leak containment, and specialized protective equipment are important considerations in both design and operation.

In summary, R-717 is a highly efficient, environmentally favorable refrigerant for certain industrial uses, balanced by significant safety considerations due to its toxicity and potential for hazardous leaks.