Verification process of pressure transmitter

Verification process of pressure transmitter
The verification process of excitation transmitter mainly includes the following parts.
First, check the accuracy of the instrument and zero it. Find the zero point, otherwise, there will be errors in the subsequent measurement process, which will have a definite impact on the measurement accuracy. The zero adjustment process is as follows: first fill the air chambers h and l with air, and then observe the indication of the ammeter. If the indication is 4 A, the zero position is correct. Otherwise, manually adjust the zero adjustment button until the indication is 4 a.
Second, the range needs to be adjusted. The specific process is to use the pressure source to slowly pressurize it to a very large value. At this time, the indication of the ammeter should be 20 A. otherwise, it is necessary to adjust the range to 20 A, and then carry out the first step of zero adjustment, and then adjust the range until the current indication is 20 mA when it is pressurized to a very large value. Note that during the process of pressurization, the pressurization speed must be controlled. If the pressurization speed is too large, the reading of current indication will be unstable, resulting in - constant error.
Third, divide the measuring range equally. When the corresponding pressure is charged into the H-switch, the corresponding output will be obtained. Repeated tests will be carried out for many times to obtain the basic error and variation between them. If the error is large, the adjustment test needs to be carried out again until the requirements are met. Before verification, the transmitter and related instruments need to be insulated to achieve thermal balance. Power on and preheat the impulse pipe and signal line. The pressure plane of excitation transmitter shall be the same as that of standard. Slowly pressurize, close the pressure source after reaching a very large value and seal for at least 15 minutes. During this time, it is necessary to ensure that there is no gas leakage in the pressure chamber and ensure air tightness. In the process of measuring, the pressure transmitter must strictly follow the national standard display error and the relevant national standards on the influence of static pressure.