In order to improve the accuracy of measuring natural gas, it is an important task to analyze and master the cause of errors in the use of measuring devices.

1.Installation error

The Sharp end of the orifice plate should follow the direction of the medium flow as the inlet end, and the flared one is the outlet end. If the installation is wrong, the display data will be small.

Solution:check the installation direction.

2.The inlet end Edge wear

If the use time is long, the geometry and size of the orifice plate will change when the measured medium is mixed with solid particles and other impurities. If the opening is enlarged or the edge of the opening becomes dull, the pressure difference will become smaller. The flow will be low.

Solution:Remachine the orifice plate to meet the requirements; if it is severe,we suggest change a new one.

3 transmitter zero drift

If used for a long time, the zero point of the transmitter may drift. If it is negative drift,the pressure difference will become smaller. The flow will be low.

Solution: calibrate the zero point of the transmitter.

4.Upstream and downstream straight pipe length is short.

If the length of the upstream and downstream straight pipe sections is not enough, The distance the gas flows is small, the measurement data will be have large error. If there are multiple elbows in the upstream straight pipe section, the measurement data will be low.

Solution: Reform the steam pipeline so that the length of the upstream and downstream straight pipe sections meets the specified requirements. Install a rectifier before the throttling device.

5 differential pressure transmitter three valve have group leak

If the high pressure valve of the three valve or balancing valve of the three valve have group leaks, the differential pressure will be reduced and the measurement data will be low.

Solution: If the high pressure valve of the three valve group leaks, tighten the valve and replace if necessary. If the balance valve in the three-valve group leaks inside, tighten the valve and replace if necessary.

6 The level of the spacer liquid is not same

From the condensate tank to the differential pressure transmitter is to separate the high temperature medium from the differential pressure transmitter to protect the differential pressure transmitter. If the liquid level height on the low pressure side is lower than the liquid level height on the high pressure side, the differential pressure will be reduced and the measured flow rate will decrease.

Solution: Check if the height of the high and low side condensation tanks is same. If not, please correct it.And check that the height of the condensate tank is higher than the steam pipe. If it is lower than the pipe,please raise the height of the condensate tank.

The accuracy of the orifice flow meter is determined by the accuracy of the differential pressure transmitter and converter. But when the accuracy of other parameters is not high, if you used high precision differential pressure transmitter also is useless.The function of the converter is mainly in monitoring the stability of the operating parameters, and its accuracy is generally no problem. So there should be a comprehensive estimate of the accuracy of the measurement in order to make the best choice for the technical economy.