In the on-site calibration of PDS pressure transmitters, due to various influencing factors, the measurement accuracy may decrease. Therefore, efforts should be made to minimize the impact on the accuracy of the measurement results and keep them within the allowable range. To reduce measurement errors, corresponding measures and methods should be taken based on the source and nature of the errors.

　　

1. Reduce the impact of static pressure error

PDS pressure transmitterUsually calibrated under atmospheric conditions at the low pressure end, but almost all cases where differential pressure transmitters are used include static pressure acting on the high and low pressure chambers of the transmitter at a certain value. The main reason for the change in output of differential pressure transmitters under static pressure is the mechanical deformation of the pressure sensing part. Although the deformation of the transmitter casting housing and the silicone oil filled in the diaphragm box is very small, the change is still significant due to the high sensitivity of the instrument. Measure static pressure error using the following two methods:

1) Single static pressure test

Apply nominal pressure to the high and low pressure chambers respectively, measure the basic error and return error after pressure relief, and their values should meet the requirements of the identification regulations.

2) Static pressure test

At the same time, apply rated pressure to both high and low pressure chambers, and the change in output lower limit value after pressure relief should comply with the requirements of the verification regulations.

　　

2. Reduce the impact of zero position changes

In differential pressure transmitters, the installation position of the differential pressure transmitter has the greatest impact on the zero position output, especially for micro differential pressure transmitters. Due to their small measurement range, the weight of the sensing components in the transmitter can also affect the output of the micro differential pressure transmitter. Therefore, it is normal for zero position changes to occur when installing micro differential pressure transmitters. The method to eliminate zero position changes is to install the pressure sensitive component of the transmitter so that its axial direction is perpendicular to the direction of gravity. If the installation conditions are limited, the zero position of the transmitter shall be adjusted to the standard value after installation and fixation. At the same time, the negative pressure chamber of the differential pressure transmitter shall be installed with a water collector, and the sewage shall be discharged frequently to avoid water accumulation affecting the accuracy.

　　

Above, we have discussed the common faults, handling methods, and diagnosis of differential pressure transmitter faults in PDS pressure transmitters.