Creating a vacuum using a dual valve pressure controller and the Venturi effect

One of our customers needed a way to control the pressure in a reaction chamber between -200 to +200 cmH2O. While the customer’s building had an ample supply of compressed air, they had no vacuum source. Without suction, they were unable to reach negative gauge pressures.

They reached out to Alicat in search of a solution that would simultaneously produce a vacuum and control pressure in their reaction chamber.

Solution: Dual valve pressure controller with a Venturi vacuum generator

We added a third party Venturi vacuum generator onto the exhaust valve of an Alicat dual valve pressure controller. This solution was smaller and more affordable than integrating a pump, and the customer was able to use their compressed air source to create the suction they needed to control to sub-atmospheric test pressures.

How does the Venturi effect work?

As fluid flows to increasingly restrictive environments, its velocity increases. This can be demonstrated by placing your thumb over the open end of a garden hose while it sprays water.

Bernoulli’s principle states that this increase in velocity is associated with a drop in pressure. Thus, fluid flow passing through a restriction will have a resultant pressure drop – this is the Venturi effect.


In the solution described above, compressed air flows through a restriction in the Venturi vacuum generator. This induces a vacuum of about one PSIA, which is plumbed to the exhaust valve of the dual valve pressure controller. This solution enabled the customer to generate a vacuum using their compressed air source and new pressure controller.

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