The Error Reasons and Corrections of Orifice Plate Flowmeter
Author:vacorda Source:vacorda.com Date: 2016-12-13 15:28:22
In the use of orifice plate flow meter, its process pipeline needs to be purged many times , so it must frequently disassemble the orifice flowmeter. If the orifice plate size is the same, errors will appear even a little carelessness, exchange orifice flowmeter will appear normal phenomenon. When installation, we must determine the flow direction of the media in the pipe and the direction of the orifice plate flow meter, or it will result in the lower measured value than actual. And we must make sure that the surface marked with "+" on the orifice meter is on the upstream side of the flow direction. The main role of the pressure pipeline is used to transfer differential pressure signal generated by orifice flowmeter, The laying length of the guide pressure pipe should be between 3 and 20 meters. If the length is too short, there will have a larger fluctuations of the flow measurement; If it is too long, the measurement hysteresis phenomenon will occur.
(Orifice plate flow meter)
In the course of industrial production, most of the gas measurement is using the standard throttle orifice flowmeter with the differential pressure transmitter. Although the differential pressure transmitter can reach a maximum accuracy of 0.075, but due to various reasons, the measurement error is also great, when the differential pressure transmitter used in industrial measurement, this problem will be more obvious. So it is of great significance that find out the reasons and solutions of the measurement error.
Orifice plate flowmeter is mainly composed of guide pressure tube, orifice plate and differential pressure transmitter, the throttle device components of the orifice plate flow meter will change the flow of media into differential pressure, differential pressure transmission from the guide pressure tube to the differential pressure transmitter membrane positive and negative pressure chamber, and the positive and negative pressure chamber diaphragm is through the silicone oil filling fluid to the differential pressure is transmitted to the measurement of the diaphragm, you can make the measurement diaphragm left and right shift.
When transporting or installation the orifice flowmeter, it will always cause the damage to the upstream and downstream surface or flange pad protruding pipe, will cause the measurement error of flowmeters. So before install the orifice flowmeter should be carefully examined the orifice plate, if the damage occur, should be promptly replaced.
The standard orifice flowmeter is designed through a large number of experiments, it can be used directly without the actual calibration, it may be irregular or even the wrong in the installation process, which will lead to flowmeter measurement error. Orifice plate flowmeter before and after the straight pipe section may not meet the requirements, the straight pipe before and after the pipeline is to ensure the flow of fluid stability,but because it will often have bifurcation, turning and other resistance parts appear, it will cause the phenomenon of fluid instability, resulting in the measurement error. So you can use before and after straight pipe with the requirements of the rational design of throttle installation location.