How to Test a Pressure Transducer?
When we get a pressure transducer, it's necessary to do detection for it. The easiest way to test a pressure transducer is to connect it to a display instrument directly. And check whether the display value changes with the pressure. If it is ok. We have to do further detection for the pressure transducer.
The main methods of pressure transducer testing are:
- The normal output signal is 0V or 4mA (signal of zero point), or the zero point potentiometer can be adjusted to 0V or 4mA.
- Connect air pressure transducer to a pressure source, such as a nitrogen or argon cylinder, and adjust the pressure reducing valve to slowly increase to see if the output changes linearly.
- Adjust full range potentiometer and check whether pressure transducer can be calibrated to full range.
After these, we can basically confirm that the pressure transducer can generally work.
In the industrial field, the digital pressure transducer that has been working normally sometimes suddenly does not display any value, that is, there is no output signal. Many people first thinking is that the pressure transducer is broken. In fact, it is not entirely true. In the industrial control system, there are many situations that can lead to no output signal. At this time, we need to check the whole system module one by one.
In order to facilitate instrument maintenance workers to quickly troubleshoot, inspection process of no output for pressure transducer is shared in a picture as shown below.
We should test pressure transducer with a multimeter. The main testing steps are as follows:
- When the pressure transducer is used with a display instrument, if there's no display on the instrument, it should be judged first whether the pressure sensor has no output or the display instrument is faulty. Measure the output of analog pressure transducer with a multimeter to see if it has a current output of 4-20mA. If the pressure transducer is used with a signal isolator and DCS, it can be judged by measuring the current with a multimeter.
- If the pressure transducer doesn't have output, check firstly whether the 24V power supply is normal. If the 24V power supply and power supply are normal, but the pressure transducer still has no output, check whether the power cord is connected reversely, whether the positive and negative poles of the signal are connected incorrectly. If they are, check whether there are open circuit faults in the whole circuit.
- If all above inspections are normal, the hardware of the pressure transducer may break. If the circuit board of pressure transducer is damaged, it directly leads to no current output. Overload or over-voltage of the pressure transducer will also lead to damage of its measuring component, which may also lead to no current output; Damage of the transducer's gauge outfit would also lead to no current output. Short-circuit the gauge outfit directly with two wires and it will be normal after short-circuit, indicating that the gauge outfit is damaged. If the LCD head has no display, check the LCD board first, and then check the circuit board. If there's still no output, check the EMI board and circuit board.