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Compact. Computer-Compatible. Watertight.
Because the superheat or subcooling is calculated right in the transducer head, control systems are greatly simplified. A standard PLC or off-the-shelf PID controller can be used with this sensor. Combining the temperature measurement and pressure measurement in one sensor simplifies installation. Having the temperature sensor extend into the fluid flow greatly
increases the accuracy and response time of the temperature measurement.
A precision thermistor in the extension tube accurately measures the refrigerant temperature. A precision, temperature compensated, pressure transducer in the transducer body accurately measures the refrigerant pressure. Electronics within the transducer head convert these measurements to a superheat or subcooling value. Data for the refrigerant properties of ammonia are stored on the base circuitry. Data for the refrigerant properties of many other refrigerants including R22, and R134a are stored on refrigerant keys that plug into the circuit board inside the NEMA 4 electrical enclosure. When one of the keys is plugged into the circuit board, the electronics use the data for the refrigerant specified by the key, instead of the ammonia data. The superheat or subcooling value is then converted to a mA output signal. 12 mA output corresponds to saturation (i.e. zero superheat, zero subcooling). 4 mA corresponds to 30°F (16.7°C) subcooling. 20 mA output corresponds to 30°F (16.7°C) superheat.
• Supply Voltage: 12-30 VDC
• Signal Output: 4-20 mA proportional to
superheat or subcooling
• Maximum Load Resistance: 1200 Ohms at
24 VDC
• Ambient Temperature Range: –20°F to +125°F
(–30°C to +50°C)
• Refrigerant Temperature:
Standard Model HPT -35ºF to +150ºF
(-37ºC to +65ºC)
• Low Temperature Model HPTL
-60ºF to +150ºF
(-51ºC to +65ºC)