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Cause analysis and solution of measurement error of orifice flowmeter

Author:    Source:    Date: 2021-06-03 15:09:11
1 Installation is not standard.
(2) The maintenance is not timely or the operation is improper.

(3) The changes in the process system or working conditions are caused by these three reasons.

1.1. Irregular installation of orifice plate

Although the design calculation of the standard throttle device orifice plate has been summarized by a large number of experiments, it can be directly put into use without actual calibration. However, the following non-standard or even error conditions may occur during the installation process, resulting in measurement errors.

Reverse loading on the upper and lower sides of the standard orifice plate: Before installation, correctly identify the flow direction of the pipeline and the direction of the orifice plate, otherwise the measured value will be at the low end. This is due to the carelessness of the construction personnel. The elimination method is to install the orifice plate and mark the orifice plate. +. The surface is located on the upstream side of the flow direction. . . Different orifice plate installation error position: This situation is generally easy to appear in the test stage. In the test phase, each process pipeline needs to be cleaned many times, and the orifice plate is removed and installed frequently. If the size of the orifice plate is the same, there will be errors with a little attention, and the orifice plate can be changed to normal.

Damage to the upper and lower surfaces of the orifice plate or the orifice flange gasket protruding from the pipe: During the process of transporting the orifice plate or installing the orifice plate by the construction personnel, it is easy to cause damage to the upper and lower stroke surfaces or the flange gasket protruding to the pipe, causing measurement errors. The elimination method is to improve the technical quality and sense of responsibility of the construction personnel. Before installing the orifice plate, the construction personnel should carefully check the orifice plate. If the orifice plate and the lower surface are found to be damaged, replace it in time; when installing the orifice plate, avoid damage to the orifice plate; when installing the flange gasket, the center line of the flange gasket Should be consistent with the centerline of the pipeline.

The straight pipe section before and after the orifice plate does not meet the requirements: the function of the straight pipe section before and after the orifice plate is to ensure the stability of the fluid flow in the pipeline. However, due to the bending, bifurcation, confluence and other resistance components on the processed pipe, the fluid is stable Turn into disturbance, causing measurement error. The elimination method is to rationally design the installation position of the throttling device according to the requirements of the front and rear straight pipes.

2. The installation of the differential pressure transmitter is not standardized

The installation environment of the differential pressure transmitter is too bad, such as large vibration, large dust or strong corrosive medium. The elimination method is to choose a suitable location to install the transmitter according to the relevant technical regulations; if it must be installed in a special environment, protective measures should be added according to the actual situation on the spot, such as adding a protective box or a fixed bracket.

3. Non-standard installation of pressure wire

The main function of the pressure guiding tube is to transmit the pressure difference generated by the orifice plate. The non-standard installation of the pressure guiding tube will cause the positive and negative pressure of the differential pressure transmitter, causing additional errors and measurement errors.

Guanghua Rd, Qingyang Dist, Chengdu, Sichuan Province, China 备案号:蜀ICP备13021392号-1