Pneumatic diaphragm pumps are one of the most widely used in the industry. This fact is due to several basic characteristics:
They have a strong and durable construction;
The materials they are made of allow them to transport a wide range of fluids: neutral, chemically active, abrasive, contaminated, containing solid impurities, fluids from rare to extremely dense - even in the form of slurries, resins and other viscous liquids, flammable substances, powdered raw materials, and others;
They can work indefinitely "in the dry", ie. without fluid, or against a closed tap at zero flow without damaging them;
They are supplied with compressed air, allowing operation in potentially hazardous environments;
There is no seal or gasket construction that makes them safe and reliable for unwanted leaks;
Low cost and lack of support.
There is rarely an industrial production where no diaphragm pumps are installed. Because these pumps come to the rescue when there is no technical solution with another type of pump or there is one, but it is too costly as an investment and subsequent maintenance. Their acquisition value is low, related to the responsibility and specificity of the process involved. To this must be added the lack of any maintenance during the operational operation. And given the easy-to-repair design and the ability to replace all working mechanisms, this makes the double-diaphragm pneumatic pump the preferred choice for an extremely wide range of applications. Moreover, the different materials used to make the individual pump components make it possible for combinations of choices that make the pump suited for the right application, to work with a specific fluid type (s).
We have to add something that is far from important. It is an opportunity to regulate the pump's output very simply and easily. Electrically powered pumps have a specific performance that depends on several basic characteristics that can hardly be influenced: engine power consumption, number and size of impellers, hydraulic part parameters and pipe connections. To change the factory-specified pump performance and to be able to regulate the pumping process, the solution is to use a frequency inverter to change the pump speed. This changes its performance. In order to use the inverter, we also need some instruments to monitor the process and supply information to the inverter (eg pressure transmitter). Thus, the technical solution is, on the one hand, more expensive, on the other - pumping already involves three components: pump, inverter, and transmitter. This leads to a tripling of the possibility of equipment failure. How can we adjust the diaphragm pump? The answer is simple: by adjusting the supply air - the flow rate or the pressure. Reducing the value of either of these two components results in a decrease in pump performance. Therefore, there are several curves in the Q-H diagram of the diaphragm pump. Each of them shows the operation of the pump at different pressure values and the consumption of the supplied air. Thus, in practice, no additional investment is needed to obtain different pumping capacity from the same pump.