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HVACR318 - Refrigeration II. Metering Devices. Metering Devices – Four Types. Capillary Tube. Thermostatic Expansion Valve. Discharge Line. Connects the compressor to the condenser. Fixed –Bore Piston. Automatic Expansion Valve. Capillary Tubes . Low Cost Device No Moving Parts
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HVACR318 - Refrigeration II Metering Devices
Metering Devices – Four Types CapillaryTube Thermostatic Expansion Valve Discharge Line • Connects the compressor to the condenser. Fixed –Bore Piston Automatic Expansion Valve
Capillary Tubes • Low Cost Device • No Moving Parts • Can be used on a wide range of applications Condenser • Rejects heat from the refrigerant
Thermostatic Expansion Valve (TXV) • Most efficient • Maintains a constant evaporator superheat • Helps prevent compressor flooding
TXV Types • Pressure Limiting • Balance Port • Externally equalized • Internally equalized • Electric Operated
Automatic Expansion Valves • Maintain a constant evaporator pressure • Used on small systems that have constant loads
Fixed-bore Metering Devices • Most common today on residential systems • Dual purpose device: • Works as a metering device • Works as a check valve • Critical charge