Air Vacuum Air Valves

Air Vacuum Air Valves can also be known as Large Orifice Air Valves and are designed to release or allow air to enter in large volumes during the filling and emptying of a piping system, or, during system failure giving vacuum protection against surge and the potentially critically damaging resulting water hammer. Air Vacuum Air Valves do not release accumulated gases whilst the system is pressurised.

Often constructed with a guided float or floating ball, it lifts with the rising liquid during filling and once pressurised remains seated against a resilient seat even if accumulated air builds-up in the valve chamber. When the pressure drops during emptying or when negative pressure occurs during a surge event the float rapidly drops allowing large quantities of air to enter the system equalising pressure. This can prevent damage to pipework and joints caused by negative pressures and the potentially catastrophic cracking or collapse of plastic or even cast iron pipework.

Air Vacuum or Large Orifice Air Valves are designed for use on all liquid transportation pipework systems, but should be carefully selected, sized and located specifically following a surge analysis or hydraulic modelling of the system. They are typically located at the high points where separation of the media, or column break, can occur, but, if incorrectly selected or located, they can actually be the cause of damage to a pipework system.

To discuss your requirement in more detail, call the MGA Controls technical team on 01704 898980 or email

We are currently in the process of updating and adding products to the website. If you have any questions or require technical advice please contact us using the form below.

There are many variants of this product available, which we hold in stock. Free technical support is available to help specify your product.

Your Name (required)

Your Email (required)

Your Company (required)


Your Message

Get the latest news and offers