69
4.4. Suction Pressure Transducer
The Suction Pressure Transducer is a 0.5 - 4.5 VDC to 0 - 250 psig ratiometric device. The
body is brass with a ¼ SAE female refrigerant connection. This transducer must be supplied
with 4.5 to 5.5 VDC power. A display reading of 0.0 psig for the transducer indicates the
device is disconnected or defective. For this device to function, 5.0 VDC must be present from
the black to the green wires on the transducer. To verify the output of the transducer, measure
the DC voltage (should read between 0.5 to 4.5 VDC) from the white to the green wires on this
transducer and use this voltage in the following formula to determine the pressure (0-250 psig).
Pressure (psig) = (62.5)*(V) – 31.25
Example, if V = 2.50 VDC, then;
Pressure (psig) = (62.5)*(2.50) – 31.25
=
156.25
–
31.25
=
125
psig.
The Suction Pressure Transducer’s replacement part number is available from Desert Aire by
calling our service department.
4.5. Discharge Pressure Transducer
The Discharge Pressure Transducer is a 0.5 - 4.5 VDC to 0 - 652 psig ratiometric device. The
body is brass with a ¼ SAE female refrigerant connection. This transducer must be supplied
with 4.5 to 5.5 VDC power. A display reading of 0.0 psig for the transducer indicates the
device is disconnected or defective. For this device to function, 5.0 VDC must be present from
the black to the green wires on the transducer. To verify the output of the transducer, measure
the DC voltage (should read between 0.5 to 4.5 VDC) from the white to the green wires on this
transducer and use this voltage in the following formula to determine the pressure (0-652psig).
Pressure (psig) = (163)*(V) – 81.5
Example, if V = 2.50 VDC, then;
Pressure (psig) = (163)*(2.50) – 81.5
=
407.5
–
81.5
=
326
psig.
The Desert Aire replacement part number for the Discharge Pressure Transducer is available
by calling our service department.
4.6. Differential Air Pressure Transducer
The Differential Air Pressure Transducer is 0.5 - 4.5 VDC to 0 – 2 inches or 0-5 inches of water
column. This transducer must be supplied with 5.0 +/- 0.25 VDC power.
4.7. CO
2
Sensor
The CO
2
sensor is a non-dispersive infrared technology (NDIR) repeatable to +/- 20ppm, +/-
1% of measured value. The output is 4-20 mA with a range of 0-2000ppm. This transducer
must be supplied with 20-30VDC/24VAC power.
Desert Aire - CM3500 Manual
Summary of Contents for CM3500 Series
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Page 5: ...5 Desert Aire CM3500 Manual Product Warning for the State of California ...
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Page 78: ...78 Desert Aire CM3500 Manual Figure 89 Addressing is now complete ...
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