Carlyle® Compressor — part of Carrier — is delivering on the global demand for natural, lower-GWP refrigerants by offering a new generation of compressors that once again work with one of the original natural refrigerants — ammonia. A carbon-neutral, nonozone depleting refrigerant, ammonia is one of the few refrigerants found naturally in the environment and has a GWP of zero.

Sixty years ago, it was not unusual to find refrigeration systems operating with Carlyle compressors pumping ammonia as the refrigerant. Then came a generation of man-made CFC and HFC refrigerants that gained widespread adoption. Now, customers have the option to go back to ammonia with Carlyle’s 5H semi-hermetic compressors which are approved to operate with low GWP ammonia refrigerant, R-717. Factory-installed options include:

• Electric solenoid unloading;

• Integrated oil pressure protection; and

• Suction and discharge valves.

The 5H41, 5H61, and 5H81 compressor models are nominally 25 HP, 40 HP and 50 HP and are well-suited for many low-temperature booster and medium applications, particularly those in food retail, ice making, and light industrial businesses. A system running ammonia as a refrigerant requires careful attention to ensure compatibility of materials, alloys, and seals. The new 5H compressors were designed specifically to operate safely under the unique characteristics of ammonia.

“Ammonia, of course, is not new to Carlyle nor the whole industry,” said Steve Holden, manager of application engineering, Carlyle. “Here we have leveraged decades of design and manufacturing experience to create a series of compressors that operate with ammonia better than anything we could have ever done in the past.”

Robert Ochs, western regional sales manager, Carlyle, recapped a recent project, “Raley’s wanted a modern design for the refrigeration system in their new supermarket in northern California. The Raley’s engineers determined that ammonia over carbon dioxide was the clear choice to deliver on environmental stewardship and efficiency. The installation and operating costs provide a financial advantage over other natural refrigerant designs. By utilizing the 5H compressor from Carlyle, they also made a smart choice for long-term reliability and performance.”

In refrigeration, ammonia is suitable for both direct expansion evaporators and flooded coolers. Ammonia is cost effective, as it is abundantly available worldwide and is not subject to disposal rules that apply to HFC/CFC refrigerants. Lower mass flow rates mean smaller piping designs that may reduce installation costs. There are currently no identified or proposed phase-outs, taxes, or F-gas regulations that wouldimpact ammonia.

To find out more about Carlyle’s 5H ammonia compressors, visit

Publication date: 4/29/2019

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