The CU-620 belongs to the CU series of spun‐copper liquid‐line filter/driers manufactured by Emerson (also marketed under the Copeland/Alco/Emerson Flow Controls umbrella).
Copeland
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Baker Distributing
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It is designed for installation in the liquid line of refrigeration or air-conditioning systems (i.e., downstream of the condenser, upstream of the expansion device) to protect the system by removing moisture, acids and particulate contamination.
rathvac.com
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Its housing is constructed entirely of copper, giving it enhanced corrosion resistance (especially useful in coastal, marine or other corrosive environments).
Baker Distributing
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The internal desiccant core is a 100% molecular sieve material, designed to adsorb water and acids in refrigerant systems using CFC, HCFC or HFC refrigerants.
rathvac.com
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Typical uses: replacement service part or original equipment installation in small‐to‐medium refrigeration/AC systems, especially where the environment may be aggressive (salt air, outdoor units).