“DX Ammonia Piping Handbook,” a guide to help engineers and designers successfully design low-charge dry expansion (DX) ammonia refrigeration systems, was released by Colmac Coil, Colville, Wash., in response to growing interest in low-charge ammonia refrigeration system.

End users of ammonia refrigeration systems are increasingly interested in these systems refrigeration systems. Benefits of such low-charge designs include reducing risk to workers and products associated with ammonia leaks as well as reducing regulatory obligations associated with a large on-site inventory of ammonia. One effective way to reduce evaporator and system ammonia charge is to design and operate the evaporator using direct expansion circuiting and controls.

DX ammonia has been used for some time in medium- and high-temperature systems ― suction temperatures above 20°F (-7°C) ― with some success, Colmac notes. However, DX ammonia has not yet been applied successfully at freezer temperatures. At suction temperatures below 20°F, certain characteristics of ammonia result in extremely poor evaporator performance unless certain concerns are addressed and mitigated.

Colmac has developed, tested and patented a low temperature DX ammonia system that it says addresses all the issues peculiar to ammonia as a refrigerant that have prevented its use at low suction temperatures.

The handbook guides readers through designing and implementing DX ammonia from -50 to 50°F (-45 to 10°C) and realizing the benefits of reduced ammonia charge, simplified controls, energy-efficient dry suction line, reduced line sizes, fast defrost, and elimination of ammonia recirculator pumps.

For more information contact Jeremy Olberding at 509-684-2595, or e-mail jeremy.olberding@colmaccoil.com.