Like other rotary pumps, a stationary vane pump also has one stator and one rotor. There is no groove in the rotor. There is one vane that does not rotate with the rotation of the rotor. Instead, it moves up and down following the different rotational positions of the rotor. Actually the tip of the vane touches the periphery of the rotor with spring pressure. The vane separates the space between the rotor and the stator into two segments. Like the rotary vane pump, there is no volumetric link between these two segments.
The stator consists of one inlet and one outlet. The position of the inlet and the outlet is opposite of the stationary vane. Both the inlet and outlet consist of the non-return valve. It is unlike the case of a rotary vane pump where the only outlet consists of a non-return valve.
A rubber pipe connects the inlet of the stationary vane pump with the vessel in which the vacuum to be created.
Working Principle of a Stationary Vane Pump
The shaft of the rotor is fitted eccentrically on the rotor. As a result, the rotor rotates eccentrically when the shaft is coupled with a prime mover. The diameter of the hollow space in the stator is such that the rotor always touches the inner peripheral wall of the stator during each position of the rotation.
For demonstrating the working principle, we have shown four stages of rotation of a stationary vane pump below. Let us consider that the rotor is rotating clockwise.
The air or any other gas or the pumping fluid coming from the vessel through the inlet valve has already filled the space between the stator and rotor. Since there is a non-return valve at the inlet of the stationary vane pump, the pumping fluid gets trapped in that space between the stator, rotor and the vane.
After a certain clockwise rotation of the rotor, the trapped fluid comes under the outlet of the pump. But due to the clockwise rotation of the rotor, the space between the stator, rotor, and vane decrease gradually. As a result, the pressure of the trapped fluid increases. Due to the forward pressure of the trapped fluid the valve associated with the outlet of the stationary vane pump opens. Therefore the fluid comes out from the outlet of the pump.
After a further clockwise rotation of the rotor, there will be a further decrements of the space under the outlet. At the same time, the space between the stator, rotor, and vane under the inlet increases. As a result, the fluid from The vessel comes in that space through the inlet valve.
This is the maximum compressed condition of the fluid under the outlet. At that position of the rotor, the discharge cycle completes. In the stationary vane pump, the suction cycle takes place simultaneously with the discharge cycle. Therefore at that position the suction cycle also completes.
The entire process of suction and discharge repeats during every rotation of the rotor. It will continue until the required vacuum is created in the vessel.
With the help of this rotary pump, we can create a vacuum in the range of 10-3 Tor. The capacity of the pump may be up to 6 liters per minute.
Use of a Stationary Vane Pump as a Compressor
There is a non-return valve fitted at the outlet of the pump. It makes the pump suitable to use as a compressor. In that case, we need to connect the outlet of the pump to the vessel in which the compressed gas or fluid is to be stored. Generally, the prime mover of this stationary vane pump is an electric motor. Therefore by controlling the speed of the motor, we can easily control the delivery and section rate of the pump.
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