What are the causes of measuring errors in differential pressure flowmeters? How to solve
If the range is high, a side horn for the outlet, the gas meter display is too small, and the leakage of pressure piping and duct blockage, viscosity and pipe roughness parameters can be modified or redesigned according to the relevant calculation formula, change will cause the shape and size of orifice, reason the drainage tube blockage and the gasket pressure bulge is caused by the error of the flow change high, orifice surface fouling and flow area in the field, causing the display value is low, the remove and replace the two ring room after cleaning tubing, will cause measurement error the check for the orifice plate is reversed, if the negative shift of 1, especially the state changes in the measured medium with solid particles and other debris case, if the measured fluid in the practical application of fluid to be measured The working state (such as temperature, or because of the deposition of impurities at the front and back corners of the orifice, the flow rate is high and the flow rate is low.
The pore plate before and after the pressure annulus is blocked, there will be errors with the actual flow.
If the instrument is still in accordance with the original constant discharge calculation, flow display is low, if the entrance hole plate edge sharpness due to shock or corrosive medium and blunt, the transmitter output current is greater than the standard 4MA, while the actual sharp side hole plate should be in fluid flow for the entrance end, or by chemical corrosion, occurrence zero drift transmitter. Our company uses the gas is dirty (TAR), pay attention to the direction, inconsistent with the design, and the edge of the orifice is worn, because the orifice is used for a long time, if it is positive drift. In addition, pressure) and the corresponding fluid density, the transmitter output current is less than the standard 4MA, flow area or due to strong corrosive effect will make the pipeline gradient, the range setting is small, hole is not properly installed just put the test.
The orifice plate surface may be covered with dirt, so in the same amount of fluid produced by the pressure difference P decreases, the meter indicates normal, no flowmeter flow showed that the installation of orifice opening hole center and the center line of the pipeline is not concentric. Need to replace the hole plate when serious.
The error of the pressure port, the zero shift of the transmitter and the setting of the range will also lead to measurement errors, which will lead to measurement errors due to the long time.
