Views: 0 Author: Site Editor Publish Time: 2021-03-03 Origin: Site
Diaphragm pump is a special form of positive displacement pump. It relies on a diaphragm to agitate back and forth to change the volume of the working chamber to suck in and discharge liquid.
Working principle of diaphragm pump
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The pneumatic diaphragm pump is mainly composed of two parts: the transmission part and the diaphragm cylinder head. The transmission part is a driving mechanism that drives the diaphragm to agitate back and forth. Its transmission forms include mechanical transmission, hydraulic transmission, and pneumatic transmission. Among them, the hydraulic transmission is widely used. The working part of the diaphragm pump is mainly composed of a crank connecting rod mechanism, a plunger, a liquid cylinder, a diaphragm, a pump body, a suction valve, and a discharge valve. Plug pumps are very similar.
When the diaphragm pump is working, the crank connecting rod mechanism drives the plunger to reciprocate under the drive of the motor. The movement of the plunger is transmitted to the diaphragm through the working liquid (generally oil) in the liquid cylinder, causing the diaphragm to agitate back and forth.
The cylinder head of the pneumatic diaphragm pump is mainly separated by a diaphragm to transport the liquid and the working liquid. When the diaphragm moves to the side of the transmission mechanism, the liquid is sucked under negative pressure when the pump works, when the diaphragm moves to the other side , Then drain the liquid. The conveyed liquid is separated from the working liquid by the diaphragm in the pump cylinder, only in contact with the pump cylinder, suction valve, discharge valve and diaphragm on the pump side, without contacting the plunger and sealing device, which makes the column Plugs and other important parts work completely in the oil medium and are in good working condition.
The diaphragm should have good flexibility and good corrosion resistance. It is usually made of Teflon, rubber and other materials. The pot-shaped parts with mesh holes on both sides of the diaphragm are provided to prevent the diaphragm from being excessively deformed locally, and are generally called diaphragm limiters. The pneumatic diaphragm pump has good sealing performance, can easily achieve leak-free operation, and can be used to transport corrosive liquids such as acids, alkalis, salts, and high-viscosity liquids.
A diaphragm is installed in each of the two symmetrical working chambers of the pump, and it is integrated by the central connecting rod. Compressed air enters the gas distribution valve from the air inlet of the pump, and the compressed air is introduced into one of the chambers through the gas distribution mechanism to push the diaphragm in the chamber to move, while the gas in the other chamber is discharged. Once the end of the stroke is reached, the air distribution mechanism automatically introduces compressed air into the other working chamber and pushes the diaphragm to move in the opposite direction, so that the two diaphragms continuously and synchronously reciprocate. In the figure, the compressed air enters the valve and moves the diaphragm to the right. The suction force of the chamber causes the medium to flow in from the inlet and push the ball valve into the chamber. The ball valve is blocked by suction; the medium in the chamber is squeezed. Push the ball valve to flow out from the outlet, and at the same time, the ball valve is blocked and prevented from flowing. In this way, the medium is continuously sucked into the inlet and the outlet is discharged.
Diaphragm pumps can be divided into three types: pneumatic, electric, and hydraulic, according to the power used by the actuators they are equipped with. That is, pneumatic diaphragm pumps with compressed air as the power source, electric diaphragm pumps with electricity as the power source, and liquid media ( Such as oil, etc.) Electro-hydraulic diaphragm pump powered by pressure.
The flow characteristic of the diaphragm pump refers to the relationship between the relative flow and displacement (relative opening of the valve) of the medium flowing through the valve. The ideal flow characteristics are mainly linear, equal percentage (logarithmic), parabolic and quick opening. The curve and spool shape are shown in Figure 1 and Figure 2. Commonly used ideal flow characteristics are only straight line, equal percentage (logarithmic) and quick opening.
The specific considerations are from the following aspects: ① From the analysis and selection of the adjustment quality of the adjustment system; ② From the situation of process piping; ③ From the analysis of load changes.
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