Operation of diaphragm pump

What is a diaphragm pump?

The name diaphragm pump derives from the diaphragm inside the pump. This diaphragm enables the pumping of liquid. The advantage is that apart from the pump head and diaphragm, no other parts of the pump come into contact with the pumped medium. This makes the application of this pump broad. The diaphragm pump is used for example as a (dirty) water pump, dosing pump and for pumping chemicals. With flows from 1 litre per hour to many cubic metres per hour, there is a diaphragm pump for every application. Handy is also that these pumps are self-priming and dry-running is often not a problem.

At Dosing Pump Shop, we specialise in dosing. Roughly from 0.1 to 1000 litres per hour. We usually deploy electrically driven membrane dosing pumps for this.

The diaphragm pump as a dosing pump

The diaphragm pump is often used as a dosing pump. If the diaphragm and the pump head of the dosing pump are made of a chemically resistant material, it is no problem to pump corrosive or aggressive liquids. After all, the liquid does not reach other internal parts of the dosing pump. Chemically resistant plastics such as PTFE (Teflon), PVDF, PP and PE are often used. These materials are chemically resistant to a wide range of chemicals. It is always wise to check which material is suitable for the chemical you want to dose! 

When dosing, it is often important to dose as precisely as possible. The diaphragm dosing pump is therefore very precisely adjustable. Most models have an adjustable stroke frequency. The fewer strokes, the less dosing takes place. For even more precise dosing, the more elaborate models often also have an adjustable stroke length. As this reduces the amplitude of the diaphragm, less fluid is pumped per stroke.

Operation of diaphragm metering pump

First, let's take a look at what parts there are. The image below gives a good idea of them.

From left to right, we can clearly see the pump head (1), the diaphragm (2) and the drive (10). These are the main components of the dosing pump.

The diaphragm is attached to the actuator shaft. As the actuator moves back and forth, the diaphragm is pulled backwards on the input stroke. This creates a negative pressure in the pump head. We can see this in the left image below. As the diaphragm (1) moves backwards, a space is created. The non-return valves (2 & 3) are open and closed, respectively, so that the fluid is drawn in. On the outward stroke, pictured below right, the diaphragm is depressed. The fluid has to go somewhere, but because of the non-return valves, it can only go towards the outgoing side, the other side is squeezed shut.

First, let's take a look at what parts there are. The image on the right gives a good idea of them.

From left to right, we can clearly see the pump head (1), the diaphragm (2) and the drive (5). These are the main components of the dosing pump.

The diaphragm is attached to the shaft of the actuator. The actuator is moved back and forth electromagnetically. This pulls the diaphragm backwards on the input stroke. This creates a negative pressure in the pump head. We can see this in the left image below. As the diaphragm (1) moves backwards, a space is created. The non-return valves (2 & 3) are open and closed, respectively, so that the fluid is drawn in. On the outward stroke, pictured below right, the diaphragm is depressed. The fluid has to go somewhere, but because of the non-return valves, it can only go towards the outgoing side, the other side is squeezed shut.