How to solve the leakage of pressure comparator?

If there is air leakage in your pressure comparator, don't rush to say that there is a quality problem in the pressure comparator. In fact, most of the time, it is because we don't pay attention to some small places. If there is a pressure leakage, please first check it according to the following methods, and maybe solve your problem soon.
1. Check whether the pressure relief valve of the pressure comparator is closed
2. Check whether the stop valve of the pressure comparator has been opened
3. Check whether the oil cup or water cup of the hydraulic pump is connected with the atmosphere
4. Remove the standard gauge and the inspected gauge, plug the plug, and then conduct pressure test
5. Whether the pressure comparator, standard gauge, pressure comparator and inspected gauge have correctly used the O-ring, and replace it if necessary