Pneumatically operated diaphragm pump ( medium: compressed air). Used in various industries for pumping fluids and liquid suspensions. Watch our video (with a transcript).

Diaphragm pump – video transcript.

Diaphragm pump! What is it? Where to use it? How does it work? Let’s watch the video.

Hi, my name is Michał Mróz. Today, I’d like to talk a little bit about diaphragm pumps.

What are their features and functions?

Pneumatic diaphragm pump characteristics.

First of all, diaphragm pumps are powered by compressed air. They can operate either partly or fully submersed. The condition for such operation is extending the air outlet above the fluid surface using, for example, a hose. You don’t need to prime this pump. It’s self-priming They are ATEX certified, so they can be used in potentially explosive areas. They can also run dry if, for example, the line is clogged. They can easily pump fluids with a large solids content, for this pump, it’s about 1.5 mm. They can pump two fluids mixing them at the same time with a 50 to 50 ratio, for example, mixing water and antifreeze.

Diaphragm pump – construction

Their construction is very simple. The body is in aluminium or polypropylene as standard but stainless steel is also available. The pump has holes so can be firmly mounted to a base. All connections are female BSP imperial pipe threads. Here is 3/8″ air supply, 1/2″ air outlet and fluid outlet, and 3/4″ fluid inlet. We offer 1/2” and 1” pumps but pumps in sizes up to 2” are available on special request.

zanurzeniowe pompy membranowe
pompy membranowe pneumatyczne

Diaphragm pump working principle

Let’s take a look at how they work. The principle is very simple. The slide valve directs compressed air to one of the chambers. There, the air pushes the membrane outwards and forces the ball in the valve number two to move up discharging the fluid, while shutting the bottom valve number one. At the same time, the other chamber makes the opposite movement producing vacuum. The ball in the valve number four shuts, the valve number three opens allowing fluid suction. There is a special valve installed in the pump which uses a pressure compensation mechanism. So no matter which position the pump stops working, it always moves back to the correct position once the pump is restarted. The material of the pump diaphragm varies depending on its application. It can be either EPDM rubber, NBR rubber but also PTFE.

pompa membranowa pneumatyczna
pompa membranowa części

Let’s see how these pumps work in practice

I’ve prepared two buckets to show you how these pumps work. There is water in one bucket and yoghurt with seeds not bigger than 1.5 mm in the other. I’ve connected three hose assemblies to the pump. One supplying compressed air, one on the inlet and one on the outlet of the pump. You can use quick release couplings to connect them or standard male thread fittings as I’ve done it. As you can hear, the pump isn’t very loud, the noise level is at 75 decibel. The pump is pumping the fluid with the pressure equal to the compressed air pressure.

Now, I will check how it handles a denser substance.

These pumps are used for pumping a wide variety of fluids, also high viscosity fluids. They are ideal for chemicals, petrochemicals, waste oils, waste water, solvents or varnish. But remember that all pumps can only be used for fluids with a flash point above 55 degrees Celsius.