Diaphragm pumps have very important properties that make them particularly suitable for use in agriculture in sprayers. Their popularity is also helped by the fact that there are manufacturers on the market, such as COMET, who offer diaphragm pumps for many and different brands of sprayers.

In today's article, the service and spare parts team at NIK brings together the 3 main advantages of diaphragm pumps compared to centrifugal pumps:

1. Excellent capacity and self-suction thrust
2. Excellent performance in dry running
3. Excellent corrosion and abrasion resistance

What exactly is a diaphragm pump?

A diaphragm pump is a type of pump that uses alternating changes in chamber volume (expansion and contraction) to generate pressure imbalances between the chamber and adjacent spaces.

Trying to compensate for the difference in pressure between two media, the liquid naturally moves from the space of greater pressure to the space of lower pressure, which causes it to move down, rise and, in short, to pump the liquid itself.

The expansion and contraction of the chamber volume that generate these pressure changes are produced by the variable bending of the diaphragm.

The diaphragm is a rubber disc placed on the piston, which separates the pumping chamber from the transmission parts and prevents the pumped liquid from contacting the mechanical parts and lubricating oil.

Due to the tightness generated by the diaphragm and the separation between the pumped liquid and the oil bath chamber, the use of a diaphragm pump has three main advantages.

1. Excellent capacity and self-suction thrust

The diaphragm pump has the ability to create a good vacuum of the suction pipeline. In practice, the diaphragm generates an excellent hermetic seal and a constant vacuum of the suction pipeline, which means that the diaphragm pump can pump liquids from levels lower than those at which it is located (thrust capacity). Pumping of 3 and 3.8 meters is normal for a diaphragm pump. So it can pump liquids from canals or pools which is a huge benefit when refueling tanks.

In addition, the diaphragm pump can work without the need to fill the suction pipe (unlike the centrifugal pump), thanks to the fact that it can suck in the air contained in the suction pipe during start-up and thus eliminate the air through the supply line (self-suction capacity).

After removing all the air, the pump works normally.

2. Excellent performance in dry running

Thanks to the hermetic separation between the pump chamber and the transmission components lubricated in an oil bath, diaphragm pumps can withstand reasonable periods of dry operation (e.g. when operating in self-suction mode or in the event of a break in the suction pipeline) without negative consequences such as overheating and blockage of the pistons, which occur with centrifugal pumps that can not run dry.

3. Excellent corrosion and abrasion resistance

Since there are no mechanical parts in direct contact with the liquid (as we said, the diaphragm creates an airtight seal between the pumping chamber and the transmission components), the diaphragm pump can pump liquids that are not perfectly filtered with residues of solid particles and sand (mechanical resistance) and can be used with most plant protection substances of water-based, including when mixed with acids, solvents, abrasive particles, sludge or slurry (corrosion resistance).

Contact our SPARE PARTS team for more information about Comet pumps