Some customers will confuse the pneumatic diaphragm pump and screw pump, the reason for the confusion, that there is common ground between the two, but in fact, the pneumatic diaphragm pump and screw pump is very different.
Pneumatic diaphragm pump and screw pump are positive displacement pump, pneumatic diaphragm pump is pneumatic, will not produce electrical spark, pneumatic diaphragm pump is a new type of conveying machinery, using compressed air as power source, for all kinds of corrosive liquid, liquid with particles, high viscosity, volatile, flammable, highly toxic liquid, can be pumped out.
Screw pump is positive displacement rotor pump, generally electric. The screw pump depends on the volume change of the sealing chamber formed by the screw and bushing to suction and discharge the liquid. Screw pump according to the number of screw is divided into single screw pump, double, three and five screw pump. Screw pump is characterized by smooth flow, small pressure pulsation, self-priming capacity, low noise, high efficiency, long life, reliable work; And its outstanding advantage is the transmission medium does not form eddy current, not sensitive to the viscosity of the medium, can transport high viscosity medium.
The two principles are the same, through the formation of a movable closed space, the fluid standard volume in front of the pump to reduce, increase after the pump, to increase the pressure before the pump, reduce the pressure after the pump effect.
Pneumatic diaphragm pump flow can be adjusted, the adjustment of the place is in the outlet of the material, pretending to throttle valve to adjust the flow. The flow rate of the screw pump is relatively stable, so its vibration will be relatively small, the noise will be relatively low.
Qigong diaphragm pump is pneumatic, relatively safe, explosion-proof and anti-static is better, Qigong diaphragm pump can transport solid fluid, chemical corrosion resistance is better. Because of the limitation that the pump film can withstand the pressure, often the pressure after the pump is not too large, the vacuum degree before the pump should not be too high. Pneumatic diaphragm pump itself does not have power equipment, need supporting air compressor, air pressure pipeline operation. Do not use nitrogen pipeline to drive, especially in confined Spaces, because it is easy to asphyxiate.
Screw pump is electric mechanical equipment, with a motor. Because it is completely mechanical transmission structure, it has a wide range of use. Notice that the velocity flow through the screw has a certain amount of heat because of the friction of the screw.
Above we briefly introduce some similarities and differences about pneumatic diaphragm pump and screw pump, the following Xiaobian to tell you about the selection of pneumatic diaphragm pump actuator suggestions!
First, the consideration of output force
Pneumatic diaphragm pump actuator no matter what type, the output force is used to overcome the effectiveness of the load (mainly refers to the unbalanced force and unbalanced torque plus friction, sealing force, gravity and other related forces). Therefore, in order to make the pneumatic diaphragm pump work normally, the actuator should be able to produce enough output force to overcome various resistance, to ensure a high seal and the opening of the valve.
For double acting pneumatic, hydraulic, electric actuator, generally have no return spring. The size of the force has nothing to do with its direction of operation. Therefore, the key to selecting the actuator is to understand the large output force and the torque of the motor. For a single acting pneumatic actuator, the output force is related to the opening of the valve. The force on the pneumatic diaphragm pump will also affect the motion characteristics, so it is required to establish a force balance in the opening range of the entire diaphragm pump.
Ii. Determination of the type of actuator
After determining the output force of the actuator, select the corresponding actuator according to the requirements of the process environment. If there are explosion-proof requirements on site, pneumatic actuator should be selected, and the junction box is explosion-proof type, electric actuator cannot be selected. If there is no explosion-proof requirement, pneumatic and electric actuator can be selected, but from the perspective of energy saving, electric actuator should be selected as far as possible. For hydraulic actuator, its use is not as extensive as pneumatic and electric actuator, but it has the characteristics of high adjustment accuracy, fast action speed and smooth. Therefore, in some cases, in order to achieve better adjustment effect, must choose hydraulic actuator, such as speed adjustment of transparent machine in power plant, temperature control of catalytic reactor in refinery.
In addition, pneumatic diaphragm pump selection, the following points also need to pay attention to understand these benefits without harm.
The spool shape structure is mainly considered according to the selected flow characteristics and unbalance force. When the temperature and pressure of the medium are high and change greatly, the material of the spool and valve seat should be selected with small changes in temperature and pressure.
Corrosion resistance due to the corrosive medium, in the case of can meet the adjustment function, try to choose simple structure valve. Wear resistance When the fluid medium is a suspension containing high concentration of wear particles, the spool and seat joint surface will be severely friction each time it is closed. Therefore, the flow path of the valve should be smooth, and the internal material of the valve should be hard.
