Air Operated Double Diaphragm Pump vs. Single Diaphragm Pump

In the field of liquid transportation, pneumatic diaphragm pump is a common and widely used pump type. Air operated diaphragm pumps use compressed air or other gases to drive the pump's movement, rather than relying on electric motors or other traditional power sources. Because the pneumatic diaphragm pump does not rely on electricity, it can work in places with unstable or no power supply. Therefore, in some special working environments, such as the field, remote areas or explosion-hazardous areas, the pneumatic diaphragm pump is a reliable and safe liquid delivery solution. And it is also suitable for various corrosive liquids, liquids with particles, high viscosity, volatile, flammable and highly toxic liquids. Pneumatic diaphragm pumps are divided into pneumatic double diaphragm pumps and pneumatic single diaphragm pumps according to their structure. So what are the differences between pneumatic double diaphragm pumps and single diaphragm pumps?

Differences in performance

Flow and pressure requirements

Pneumatic single diaphragm pumps are suitable for smaller flow and lower pressure liquid delivery, while pneumatic double diaphragm pumps are suitable for larger flow and higher pressure liquid delivery. If liquid delivery requires higher flow and pressure, it is more appropriate to choose a double diaphragm pump.

Tightness

The air operated double diaphragm pump adopts a double diaphragm structure, so that the liquid is sandwiched between the two diaphragms, which enhances the sealing of the pump and reduces the possibility of leakage and volatilization. In contrast, single diaphragm pumps have relatively low sealing performance and are not suitable for handling liquids with strict leakage requirements.   

Cost

Because the double diaphragm structure of the pneumatic double diaphragm pump is relatively complicated, the manufacturing cost is relatively high, so the price is also high. The dual-diaphragm construction also means that more attention and patience are required during maintenance and repairs. In contrast, the pneumatic single diaphragm pump is relatively low in cost due to its simple structure, and the price is more affordable. Maintenance and maintenance are relatively simple, and repair costs are relatively low.

Differences in structure and working principle

Air operated single diaphragm pumps usually consist of a pump chamber and a diaphragm. After the compressed air enters the gas distribution device, it directly pushes the diaphragm to move, and the upper and lower single-way valve balls change the volume of the pump cavity through the movement of the diaphragm to push the liquid out. When the diaphragm is formed, the gas distribution device will pull the diaphragm back to its original position. At this time, there will be an exhaust action. After the exhaust action is completed, the gas distribution device will directly push the gas to the diaphragm, squeezing the pump chamber to continuously suck and discharge the liquid.

Pneumatic double diaphragm pumps are generally composed of two symmetrical pump chambers on the left and right. Double diaphragm structures are used. In the two symmetrical working chambers of the double diaphragm pump, each is equipped with an elastic diaphragm. At the same time, the gas in the other working chamber is discharged from the back of the diaphragm. Once the end of the stroke is reached, the gas distribution mechanism will automatically introduce compressed air into the other working chamber, pushing the diaphragm to move in the opposite direction, thus forming the synchronous reciprocating motion of the two diaphragms. There are two one-way ball valves in each working chamber. The reciprocating movement of the diaphragm causes the volume of the working chamber to change, forcing the two one-way ball valves to open and close alternately, so that the liquid is continuously sucked and discharged.

Differences in application scenarios

Due to its simple structure, wide application range, and low cost, the pneumatic single diaphragm pump is suitable for general liquid delivery scenarios with low flow and pressure requirements, such as small industrial applications, laboratory experiments, and small flow liquid processing.

The pneumatic double diaphragm pump has a double diaphragm structure, high flow and pressure adaptability, and good sealing performance. It is suitable for more complex liquid delivery scenarios that require high flow and pressure, and strict requirements on the sealing performance of the pump. It is especially suitable for chemical, petroleum, pharmaceutical and other industrial fields.