How to wire a 4-wire pressure transmitter

Other Hardware Sensors
21

I don't understand? Currently there is nitrogen in the pipe that the transducer is connected to, and the contractor told me he charged it with 70 psi nitrogen for now. So shouldn't I get that reading?

22

That is for you to determine. At present, you have no way to know whether the sensor is working correctly.

It is a good idea to test sensors before installation in the final location.

23

Simple test sketch for the 100pis sensor.
Change 100.0 to 500.0 for the 500psi version.
Calibrate '102' to get zero psi without pressure.
Calibrate '922' for 100psi readout with 100psi pressure, assuming you have the gear to calibrate.
Leo..

const byte sensorPin = A0;
float sensorRating = 100.0; // 100psi sensor
int offset = 102; // zero pressure adjust (10% of A/D)
int fullScale = 922; // max pressure adjust (90% of A/D)
float pressure; // final pressure

void setup() {
  Serial.begin(9600);
}

void loop() {
  pressure = (analogRead(sensorPin) - offset) * sensorRating / (fullScale - offset);
  
  Serial.print("Pressure: ");
  Serial.print(pressure, 1); // one decimal place is all you get
  Serial.println(" psi");
  delay(500);
}
24

Depends if it as absolute or relative transducer. If you have a relative transducer and zero at 70 PSI then 70 PSI is your baseline.

25

then ambient atmospheric pressure is the baseline.

26

What pressure are you reading? How did you connect the sensor to the pipe? Maybe the precharge leaked out.

27

Normally you don't add a transducer to a live system as whatever you're measuring will leak out. Start with a cold, unpressurized system and make sure you're properly zero'd. THEN charge to system to an KNOWN reference pressure and adjust the SPAN (AKA GAIN) to give a full scale reading. Then your system can go live with a reasonable expectation of success.

28

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