On-site testing of pressure gauges should pay attention to matters

When the on-site inspection pressure gauge Xi'an Pressure Instrument Research Institute encounters a variety of problems, we need to use professional knowledge to carefully analyze in order to find the problem. Because there are many influencing factors for on-site inspections and they cannot be controlled, we should not be hastily and should be responsible. Here we discuss the issues that should be noticed in the on-site inspection of pressure instruments.

Remote transmission pressure gauge can be remotely transmitted because there is a sliding wire resistor inside, and its sliding end is connected with the end of the spring tube. When the pressure gauge is under pressure, the end of the spring tube is displaced to move the sliding end of the resistor. The resistance value changes, and the change of the resistance value is received by a display meter located in a remote control room, and is converted into a corresponding pressure value to be displayed, thereby realizing the pressure remote transmission function. For a remote pressure gauge and its corresponding display, a resistance value corresponds to a corresponding pressure value. Therefore, when there is no pressure, the signal received by the display meter should show zero when converted; when the pressure is at the maximum value, the display meter should show the maximum value. If the display is incorrect, the display settings can be adjusted. Since the remote pressure gauge has the same range, the zero point and full-scale output value of each block are also different. Therefore, each remote pressure gauge and digital display meter are the only ones corresponding to each other and have no interchangeability. If you replace the pressure gauge or the digital display, you should recalibrate it. Some users have the potential for safety hazards by changing or swapping instruments without retesting. If the zero point and full scale are correct and the deviation in the middle indication is too large for on-site inspection, the remote pressure gauge should be separately tested to check if the output is linear. If the linearity is not good, the remote pressure gauge should be replaced.

Next, we give an example of the on-site inspection of the transmitter:

For example, if the output of a meter factory is a (4 to 20) mA transmitter, if the zero point (4mA) is adjusted and the output is 20.100mA at full scale, adjust the full-scale knob to adjust the amount to (20.100- 20.000) × 1/4 = 0.025 mA, and the full-scale output is (20.000-0.025) = 19.9775 mA. The zero output after the pressure relief is approximately 3.975 mA, adjust the zero point to 4.000 mA, and then pressurize to full-scale adjustment. Repeated adjustment until the zero and full scale meet the requirements.