What are air valves used for?

For a liquid piping system to operate efficiently, it needs to have air and wastewater gases continuously removed. Air valves exist for this purpose. They are used during operation of liquid piping systems to release air or wastewater gases that are admitted or emitted, as and when needed.

How does an air valve work?

Air naturally collects at the highest points in a pipeline. This is where small orifice air release valves are usually found. When air enters the air valve, it lowers the level of the liquid inside it. Should the level drop below a certain point, the valve is triggered to open, thus venting air out of the piping system.As the air vents from the valve, liquid re-enters the valve body, eventually to the appropriate level needed for the valve to close. This process repeats as and when necessary.Large orifice air valves work by allowing the automatic ventilation of a pipeline during filling and emptying. When filling, air is exhausted at a sufficiently high capacity to prevent restriction of the filling rate due to built up back pressure. When emptying, air is admitted to the pipeline at a rate sufficient to prevent high vacuum pressures developing.

Diaphragm Valves

Diaphragm Valves by John Valves

A diaphragm valve is used for both isolation and throttling duties. It is manufactured with an elastomeric diaphragm that is pressed by a plug above the diaphragm into the flow to throttle or isolate the flow of the media. Complete isolation occurs when the diaphragm comes in contact with the seat inside the valve body.

Diaphragm valves are available in “straight-through” or “weir” styles. In a weir-style diaphragm valve, the internal body surface is shaped such that the media flows over a ridge or saddle. This type is better suited for throttling applications due to its quick opening characteristic. As the straight-through valve name suggests, it has a straight through flow path. However, it is not a full port, as the diaphragm protrudes into the flow at the top of the valve. These give better flow characteristics than “weir” style valves making them better suited for slurries, sludges, etc. They are not as accurate when throttling or suitable for higher temperature fluids due to the design of the diaphragm having to be more flexible to seal on the bottom of the valve body.

Both types of diaphragm valves can be used for abrasive media and chemical applications as the valve bodies can be lined with rubber or PTFE and the diaphragm material can be selected to suit the applicable media.

Diaphragm Valves Technical Information

Frequently Asked Questions About Diaphragm Valves

Got questions? Below are some of the questions we get asked often about diaphragm valves.

What does a diaphragm valve do?

A diaphragm valve serves the purpose of both isolation and throttling duties. It is designed to control the flow of fluids by utilising an elastomeric diaphragm. When the valve is in operation, the diaphragm is pressed by a plug or disc against a seat within the valve body, effectively throttling or isolating the flow of the media.

Are diaphragm valves unidirectional or bi-directional?

Diaphragm valves are typically bi-directional, meaning they can handle fluid flow in both directions. They can be used for on-off applications as well as throttling duties, allowing control over the flow rate and velocity of the media. The diaphragm design enables effective regulation of fluid flow by adjusting the area through which the media can enter and exit the valve. This bi-directional capability enhances the versatility and functionality of diaphragm valves in various applications.

Diaphragm Valves

Diaphragm Valves by John Valves

Diaphragm Valves Technical Information

Frequently Asked Questions About Diaphragm Valves

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