How to install the diaphragm pump
In principle, a diaphragm pump is no different from a plunger pump with an installed diaphragm separating the pressure chamber into a pumping chamber, the working space, and a hydraulic chamber, as shown in figure. Here, the diaphragm is a flexible yet statically tight partition. The pressure on both sides of the diaphragm is almost exactly equal during normal operation. Simply put, the diaphragm transfers the plunger stroke from the hydraulic fluid to the pumped fluid.
Figure : Plunger pump with installed diaphragm
This simple step alone substantially improves the design. The simple diaphragm pump now has more advantages compared to the plunger pump. One advantage is that the plunger seal is only in contact with hydraulic oil. This reduces wear, and the pumped fluid is not contaminated by dust from abrasion. The fluid chamber is hermetically tight. Consequently, no pumped fluid leaks into the environment. Furthermore, the pump is absolutely dry-run safe with still high efficiency.
Some disadvantages remain, however; as a result, this simple design is not yet functional. Unavoidable leaked oil at the plunger seal escapes into the environment. Oil leakage causes a reduction in the oil volume in the hydraulic chamber. This is why the diaphragm would then be moved back gradually toward the plunger and finally overstretched.
In the next step, a strategy for catching leakage and preventing damage to the diaphragm due to overstretching must be considered.