What Is a Small Orifice Air Relief Valve?

A guide to understanding function, purpose, and benefits

Definition: Small Orifice Air Relief Valve

 A small orifice air relief valve (also referred to as a single small air release valve) is a type of automatic valve designed to discharge small, accumulated quantities of air from pressurised pipelines while the system is in operation.

 Unlike manual vents, these valves continuously and automatically remove trapped air, ensuring smooth flow and reducing the risk of performance issues.

How Does a Small Orifice Air Relief Valve Work?

 The valve operates using a simple float mechanism inside a chamber:

• Air Collection – As water flows, dissolved air naturally separates and collects at high points in the pipeline.
• Detection – The collected air lowers the water level in the chamber, dropping the float.
• Release – The float movement opens a small orifice, venting the air to atmosphere.
• Sealing – Once air is released, the chamber refills with water, raising the float to reseal the orifice.

 This cycle repeats automatically, keeping the system free of unwanted air pockets.

Why Are Small Orifice Air Relief Valves Important?

• Efficiency: Prevents air locks that restrict water flow and increase pumping costs.
• Protection: Reduces pressure surges, vibration, and water hammer that can damage fittings and pumps.
• Longevity: Safeguards meters, valves, and pipework from unnecessary stress.
• Automation: Works continuously without operator intervention.

Typical Applications

 Small orifice air relief valves are commonly used in:

• Water distribution networks – at high points where air collects
• Rising mains – to prevent air locks in long pipelines
• Pump stations – downstream of pumps to remove dissolved air
• Irrigation systems – to ensure smooth and reliable operation

Summary

So, what is a small orifice air relief valve?
 It’s a compact, automatic device that protects pipelines from the hidden but damaging effects of trapped air. By releasing small accumulations continuously, it ensures reliable operation, reduced costs, and longer equipment life.

 If you’re beginning your search to solve air build-up problems in water pipelines, this valve is often the simplest and most effective answer.