Nitrogen sealing valve working principle and fault repair

There are two forms of nitrogen storage tanks in normal operation, the nitrogen source pressure of these two forms of nitrogen are nitrogen from the nitrogen cylinder, nitrogen pressure is high, but the nitrogen pipeline is fine, there is no pressure reducing valve, and Directly into the self-energizing nitrogen sealing valve, the self-acting nitrogen sealing valve has the function of automatic pressure adjustment, there is no need to set the pressure reducing valve in front, the nitrogen sealing pressure of the storage tank is very low, we control the ± 500pa, for the protection of the storage tank One type is controlled by a nitrogen sealing valve mounted on the top of the tank matched with a self-energizing nitrogen sealing valve. The nitrogen sealing valve is also provided by a self-operating regulator valve manufacturer. The function of the nitrogen sealing valve is to adjust with the self-adjusting valve. The valve works as a safety function. When the pressure is too high, for example, when the pressure of the tank is +500 Pa, although the nitrogen sealing valve stops entering nitrogen gas, when the tank continues to enter the material, the pressure of the tank rises. The material in the tank is discharged through the nitrogen-sealing valve to maintain the pressure of the gas in the tank not exceeding +500pa, so that the tank is not overpressured. We do not have a safety valve, but control it through the nitrogen sealing valve. When the tank pressure will be lower than -500 At the time of pa, the self-operated regulator enters nitrogen to keep the tank pressure from becoming too low.

There is also a form of self-regulating valve with a double seal water tank, storage tank pressure is controlled ± 500pa, the working principle is basically the same, when the pressure reaches +500pa, the gas in the tank breaks the water in the respiratory tank The seal maintains the pressure in the tank not exceeding +500pa. When the pressure in the tank is too low, on the one hand, the self-operated regulator valve replenish nitrogen to the tank to maintain the nitrogen pressure not too low, in case of self-regulation. When the valve fails, another water seal of the breathing tank plays a role. The outside air breaks through the other water seal and enters the tank to maintain the tank pressure not too low to -500pa, avoiding the abuse of the tank. This form is also There is no safety valve. The above-mentioned form prevents the overpressure phenomenon that may be caused by the positive pressure of the storage tank, and also avoids the possibility of the storage tank sucking caused by the negative pressure of the storage tank and ensures the safety of the storage tank.

Failure Analysis and Treatment (1) During the initial driving of a large aromatic device, it was found that 24 nitrogen sealing valves were not working properly. After the valve was dismantled, it was found that the air-tight valve, the main valve, and the two valve core inner walls of the nitrogen-sealed valve were stained with a thick layer of dirt and wiped and greased. Some welding slag was found at the valve seat, which caused rust in the pipeline after driving and residual impurities to be blown by nitrogen into the nitrogen sealing valve, so that the main valve could not return to the valve seat.

(2) The pressure tube is blocked. If the pressure guiding tube is clogged, the nitrogen sealing valve has no feedback signal, which can also cause nitrogen gas to constantly replenish into the tank. Check whether the reason is as follows according to the procedure shown in Figure 3.

(3) The spring force becomes smaller. If the pilot valve, the main valve and the two valve core chambers are not dirty, and the pressure guiding tube is not blocked, check the spring force of the small spring below the air guiding valve. If the elastic force is reduced, the nitrogen sealing valve will continue to replenish the air. . You can stretch the spring to increase its spring force.

(4) The seal ring is damaged. Air guide valves operate more frequently during operation. The seal ring is often subjected to the impact of the valve seat, resulting in the seal ring worn or broken, does not achieve the sealing effect, replace the seal ring can be.

(5) The inlet of the control gas and the outlet of the pilot valve are reversed. This is a product quality issue. Combined with the working principle of the nitrogen sealing valve, you can make a judgment.