In the process of transporting the orifice plate or installing the orifice plate by the construction personnel, it is easy to cause damage to the upstream and downstream surfaces or the flange gasket to protrude out of the pipeline, resulting in measurement errors. The elimination method is to improve the technical quality and sense of responsibility of the construction personnel. The construction personnel should carefully check the orifice plate before installing the orifice plate. If the downstream surface of the orifice plate is found to be damaged, it should be replaced in time; during the installation of the orifice plate, avoid damaging the orifice plate; The centerline of the gasket is consistent with the centerline of the pipe.

 

3. The downstream surface of the orifice plate is reversed

 

Before installation, correctly identify the flow direction of the medium in the pipeline and the direction of the orifice plate, otherwise the measured value will be low. This is due to the carelessness of the construction personnel. The elimination method is to make the surface marked with "+" on the orifice plate on the upstream side of the flow direction when installing the orifice plate.

 

4. Different orifice plates are installed in the wrong position

 

This situation is usually particularly easy to occur during the test run phase. During the commissioning phase, each process pipeline needs to be purged multiple times, and the orifice plate is frequently disassembled and assembled. If the size of the orifice plate is the same, errors will occur if you don't pay attention, and the orifice plate can be replaced to restore normal.

 

It can be seen that in order for the instrument to exert its maximum function and effect, the correct selection is the first condition, and the correct installation is the decisive factor.

 

Precautions before installation of orifice flowmeter

 

1. Before the installation of the instrument, the process pipeline should be purged to prevent the ferromagnetic substance remaining in the pipeline from adhering to the instrument, affecting the performance of the instrument, or even damaging the instrument. If it is unavoidable, a magnetic filter should be installed at the entrance of the meter. The instrument itself does not participate in the air sweep before production to avoid damage to the instrument.

 

2. Before the instrument is installed in the process pipeline, it should be checked for damage.

 

3. The installation form of the instrument is divided into vertical installation and horizontal installation. If it is a vertical installation, the angle between the center vertical line and the plumb line of the instrument should be less than 2°; if it is installed horizontally, the horizontal center line of the instrument should be The horizontal angle is less than 2°.

 

4. The upstream and downstream pipelines of the instrument should have the same caliber of the instrument, and the connecting flange or thread should match the flange and thread of the instrument. The length of the upstream straight pipe of the instrument should be at least 5 times the nominal diameter of the instrument, and the length of the downstream straight pipe should be greater than Equal to 250mm.

 

5. Since the meter transmits signals through magnetic coupling, in order to ensure the performance of the meter, no ferromagnetic materials are allowed to exist at least 250px around the installation.

 

6. The meter for measuring gas is calibrated under a specific pressure. If the gas is directly discharged to the atmosphere at the outlet of the meter, it will cause a pressure drop at the float and cause data distortion. If it is such a working condition, a valve should be installed at the outlet of the instrument.

 

7. The instrument installed in the pipeline should not be subjected to stress, and the entrance and exit of the instrument should be supported by suitable pipelines to keep the instrument in a state of minimum stress.

 

8. When installing PTFE (polytetrafluoroethylene) lined meters, be especially careful. Because PTFE will deform under pressure, do not overtighten flange nuts at will.

 

9. For instruments with liquid crystal display, try to avoid direct sunlight to the display during installation to reduce the service life of the liquid crystal.

 

10. When measuring low temperature media, the jacket type is required.