When the applied pressure reaches the upper limit scale value of the pressure gauge measurement, the pointer of the pressure gauge still does not move or rarely moves
It means that the pressure is not transmitted to the spring tube. First check whether the sealing gasket connected to the pressure gauge calibrator blocks the channel at the joint. If there is no problem at the connection, it proves that the internal pressure gauge is blocked and should be cleaned.
When we use the pressure gauge, we often encounter the following problems (with solutions):
1. After the pressure is removed, the pointer cannot return to zero
1) The pointer is bent or loose, it can be corrected with tweezers, and it should be tightened after verification.
2) The balance spring torque is insufficient, the meshing of the central gear and the sector gear can be disengaged, and the central gear shaft is turned counterclockwise to increase the balance spring torque.
2. The pressure gauge pointer jumps or sluggishly does not turn
1) There is friction between the pointer and 3) the transmission gear. Adjust the meshing clearance of the transmission gear.
There is friction on the surface glass or dial. It can correct the pointer, thicken the gasket under the glass or twist the pointer shaft hole.
2) The center gear shaft is bent, the shaft diameter is not concentric, and does not match. The gear can be removed and straightened with a wooden hammer or straightened with flat-nose pliers;
3) There is dirt at the meshing position of the two gears, and the two gears can be removed for cleaning.
4) The movable screw between the connecting rod and the sector gear is inactive or loose, and the thickness of the connecting rod can be thinned with a file.
3. Only one test point is out of tolerance
1) On which scale you find out of tolerance, you stop on that scale. Check the coordination of various parts on the scale point, whether the transmission shaft hole is blocked; whether the connecting rod is flexible; whether the tooth meshing point is damaged or foreign objects are eliminated.
2) When a positive error occurs at a certain point, it is often due to dirt and burrs at the meshing point of the tooth; when a negative error occurs, it is mostly due to the shape of the tooth or damage to the tooth. If the teeth are seriously damaged, they should be replaced with new ones. When there is no replacement of new parts, the center wheel has a damaged tooth that can change the meshing position, so that the damaged tooth avoids the transmission. If the fan-shaped wheel has broken teeth, it cannot be repaired and must be replaced with a new one.
How to solve the problems in the use of pressure gauge
4. In use, the indicated value is not stable and the pressure drops significantly
At this time, first check whether there is oil leakage at the connection between the pressure gauge and the pressure gauge calibrator. If there is no oil leakage, the calibrator is intact, indicating that the spring tube is leaking, and the scale plate should be removed for further inspection.
1) The base itself has trachoma, which gradually produces leakage after long-term use. Need to replace the base of the same specification, repair welding at low pressure.
2) Long-term exposure to pulse pressure, spring tube fatigue or leakage at the sealing parts at both ends. The two sealing parts can be repaired or re-tightened, and the spring tube is scrapped if it breaks.
3) Long-term corrosion by the measured medium, the spring tube causes leakage. It is necessary to select a pressure gauge with corrosion resistance and replace the spring tube if necessary.
4) Due to the quality problem of the spring tube, there are obvious cracks or ruptures. Need to replace high-quality spring tubes of the same specifications and take corresponding protective measures.
5) Improper specification is selected, the measured pressure is close to the upper measurement limit of the meter, and long-term pressure will cause fatigue and rupture. The pressure gauge of the appropriate specification should be carefully selected. If the spring tube is broken, the pipe of the same specification should be updated.
5. Uneven pressure error
1) The spring tube is deformed and the displacement is not proportional to the pressure, so the spring tube needs to be replaced.
2) Improper adjustment of the free end of the spring tube and the sector gear and wheel rod transmission ratio requires re-examination and adjustment.
3) The coupling position of the gear splint and the bottom plate is not correct. The coupling screw should be loosened to drive the splint counterclockwise.
4) The displacement of the pointer causes the spring to be unevenly biased forward or backward. The spring tension can be adjusted to rotate the central gear.
6. During the pressurization process, the pressure gauge pointer jumps, stagnate, and deteriorates greatly.
It means there is friction in the transmission mechanism, and the meter must be disassembled to check the meshing of the transmission mechanism and carry out necessary treatment.
7. The error of the checked table always increases or decreases by a fixed value
According to the characteristics of this error, we can conclude that the error of the tested meter increases or decreases by the same amount as the pressure increases. In the entire measurement range, the pointer reading always differs from the standard indication by a fixed value. This is a systematic error caused by incorrect pointer installation. We don't have to worry about it particularly. Because it is very easy to adjust this error, just restart the needle to adjust.
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