Gear oil pump safety valve calibration and maintenance should be comprehensively tested. The technical performance indicators of the safety valve must be a full performance test. The most basic requirement of the test is to have actual operating conditions or even exceed actual operating conditions. In addition to equipment such as high-temperature and high-pressure vessels, such a test device also has a rapid measuring instrument with various parameters, and ensures a high-temperature and high-pressure steam source with a large flow rate, which is costly.
Calibration is part of the safety valve test and is the main project of the factory's factory test. Before the factory, the opening pressure setting and sealing test of the air medium are generally carried out using a normal temperature safety valve calibration table. The safety valve normal temperature calibration table can only be used for opening pressure setting and sealing test.
1. Under what circumstances does the safety valve need to be calibrated? 1) Long-term storage or before the first use 2) Periodic verification 3) Valves with severe damage and corrosion 4) Valves with missing valve nameplates 5) Valves with damaged seals The meaning of the adjustment of the return pressure and the method of the return pressure defined by the national standard means that after the safety valve reaches the discharge state, the pressure of the medium drops to a certain value, and the valve flap is again in contact with the valve seat, that is, the opening height becomes zero, at the inlet of the valve. Static pressure, the return pressure is too low and too high is not good, too low will cause loss of medium and energy, too high will not reach the discharge, causing the frequency of the valve jump, the principle is to achieve the discharge as much as possible Increase the return pressure and reduce the loss of media and energy.
Third, the adjustment method is back to the seat pressure is adjusted by the adjustment ring, the principle of adjustment is the principle of the gap, the smaller the gap, the greater the resistance when the spray, the greater the force to hold the spool, the more difficult to return to the seat, and vice versa, The larger the gap, the easier it is for the spool to fall back and the higher the return pressure. For the safety valve with only the lower adjustment ring, the adjustment ring is adjusted upwards, the return pressure is lowered, the adjustment ring is adjusted downward, and the return pressure is increased; for the safety valve with the upper and lower adjustment rings, the distance between the upper and lower adjustment rings is reduced, and the return pressure is reduced. Lower, the distance between the upper and lower adjustment rings increases, and the return pressure increases.
Fourth, the calibration method and its advantages and disadvantages Safety valve calibration has two methods of on-site calibration (on-line verification) and calibration station verification. If conditions permit, it should be verified on the spot as possible, because the on-site calibration is more realistic. Working conditions are therefore more reliable. Advantages of on-site calibration: It is convenient for the verification of welded safety valve. It can measure the pressure of return seat and the measurement is accurate. The disadvantage is that the calibration time is long, the system needs to be repeatedly boosted, it is not economical, it is dangerous, and it can not be used for sealing test. .
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