Pressure Gauge Repair Experience
The pressure gauge is the most common and widely used instrument in industrial production control, and it is also the simplest pressure detection indicator instrument because of its low price, easy installation and use, and intuitive instructions. It is widely used.
However, the maintenance and maintenance of pressure gauges are often neglected in daily instrument maintenance, and some pressure gauges are inaccurately indicated throughout the year, which brings great hidden dangers to production. Sum up the experience and experience combined with the actual work.
Common faults in calibration can be roughly divided into several categories:
1. The pointer of the force meter does not return to zero.
This is mainly due to the elastic inertia of the paralyzed tube of the spring tube pressure gauge after a period of use, which causes the initial displacement of the spring tube to send changes.
That is, the long-term elastic aftereffect makes the elastic inertness larger, which can be understood as zero drift. The way to eliminate this fault is usually the fixed needle. When the pressure calibrator is not pressurized, the needle of the pressure gauge is opened and fixed to the zero position again, so that the current initial position is treated as a zero point to achieve zero adjustments.
Normally, the accuracy of calibration with a pressure gauge after needle setting is most suitable for the original requirements. For example, the return error, linearity, accuracy, and tap displacement are most qualified. If it is not ideal, further adjustments can be made according to the actual situation.
2. The firmware is loose.
After the pointer does not return to zero, the calibration is not ideal. The reason is that the fastener is loose. It is mainly due to the loosening of the adjustment screw connecting the tie rod and the sector gear. Its original position changes, which causes the displacement magnification of the paralysis tube to change.
Causing the pointer indication of the pressure gauge to become larger or smaller. This can be restored by adjusting the position of the adjusting screw under standard pressure and then fixed to restore the magnification of the original pressure gauge to make the pointer indication accurate.
In addition, check whether the tightening screw is loose after the pressure gauge core and whether the fixing pin of the connection between the spring tube and the pull rod is broken.
3. The central gear is seriously worn.
This failure often occurs in situations where the pump outlet pressure fluctuates greatly. In actual use, because the pressure valve opening is large, the buffer tank is not designed or the effect is not ideal, resulting in the pressure gauge pointer fluctuating frequently within a pressure range, such as the plunger.
The pressure gauge at the outlet of the pump fluctuates frequently within a pressure range for a long time, causing the sector gear and the central gear to frequently mesh and rotate, and increased friction causes some gears to be damaged.
Therefore, the pressure gauge card set or just the phenomenon of inaccurate indication is not returned. To eliminate this fault, only the central gear and the sector gear can be replaced. During operation, the lower fixed base plate can be replaced together.
4. The elasticity of the hairspring becomes weak or damaged.
This also occurs mainly in occasions with frequent pressure fluctuations, and the elasticity of the balance spring for a long time is weakened. If the pressure line on the north side holds back the pressure or the pressure tube of the pressure gauge freezes or condenses, causing the needle of the pressure gauge to overturn and damage the balance spring, this can also be repaired by replacing the bottom plate.
5. Spring tube deformation
The deformation mentioned here mainly refers to elastic deformation, and such failures often appear on the current pressure gauges. The spring core of the early pressure gauge is thick, regardless of the wall and diameter of the tube, so the impact resistance and elastic inertia of the spring tube are small, that is, the range of Hook’s law is large and the life is long.
Therefore, the pressure of the spring tube is long-term. The relationship does not change (the amount of change is small). The wall and diameter of the spring tube used by the current pressure gauge manufacturer are very small, and the pressure resistance and elasticity of the long-term use become poor, and the life is shortened. The main performance is that the range of Hooke’s law of the spring tube becomes smaller.
The linear area keeps increasing, making the pressure-displacement linear relationship range smaller, so there is a phenomenon of non-linearity and even the deformation and distortion of the pressure gauge spring tube, which even causes the danger of medium leakage. The spring tubes with non-linear changes can only be scrapped.
The above is the summary of the maintenance process of ordinary spring tube pressure gauges in daily maintenance. I hope it will help you in the process of using the pressure gauge.