Pneumatic door valve fittings will work in accordance with the principle of moment balance. When the signal pressure to the bellows increases, this will cause the main lever to rotate around the fulcrum. At this time, the nozzle baffle will be close to the nozzle. After the nozzle back pressure is amplified by the one-way amplifier, the pressure that passes into the membrane chamber of the actuator increases, and at this time it also moves downward toward the valve stem.
The use of the positioner of the pneumatic door valve will actually drive the feedback lever to rotate around the fulcrum. The feedback cam will also rotate as a counterclockwise direction. The auxiliary lever will rotate around the fulcrum through the roller, and then the feedback spring will be stretched. When the pulling force and signal pressure of the main lever balance the moment when the force on the bellows reaches balance, the meter reaches equilibrium.
The valve position of the actuator on the positioner of the pneumatic valve is actually maintained at a certain degree of opening. A certain signal pressure corresponds to a certain opening of the valve position. The above-mentioned mode of action is also referred to as corrective action. If the mode of action is to be changed, the cam should be turned over at this time, and the A direction becomes B direction, and so on.
As for the positive positioner on the positioner of the pneumatic valve, this means that the signal pressure increases and the output pressure will increase. The so-called reactive positioner means that the signal pressure increases and the output pressure decreases. . At this time, we actually need to pay attention to the fact that as long as a positive acting actuator is equipped with a reaction locator, it can also realize the action of a counteracting actuator.
In contrast, a counter-acting actuator only needs to be equipped with a reaction locator. At this time, the action of the positive-acting actuator can also be achieved. The action at this time will have an impact on the equipment applied to the pneumatic door valve fittings. Therefore, the use of the positioner of the pneumatic door valve fitting is carried out on the application of the principle, and the production quality can also be guaranteed.http://www.pump-casting.com