The art of engineering air operated double diaphragm pumps

Ballvalve

Since the first introduction to the market in the 1950s, the construction and basic working principles of air operated diaphragm pumps have remained very similar to the early double diaphragm pumps. The construction looks very straight-forward, but due to the alternating working principle of the pump, special care has to be made to keep the pumps leak tight.

There are two zones which have to be sealed to keep the liquid inside the pump: the contact between the diaphragm and the outer pump chamber and the contact between the manifolds and the outer pump chamber.

Traditionally, clamping bands or bolts are used to seal the zones adjacent to the pump chamber. By using clamps, especially on bigger pumps and on applications with products of higher viscosity, the stress caused by the movement of the pumps can lead to leakages. For this reason, Verder has chosen to use bolted versions as standard. The bolts are divided over the sealing surface to equalize the pressure over the sealing area.

The drawings illustrate the sealing principle between the manifolds and the outer pump chambers.  

Although it initially seems straight-forward, a high degree of engineering is necessary to construct a perfect leak-tight pump as the Verderair proves to be.