Air Vent Valve

Introduction To Air Vent Valves

An Air Vent Valve is installed in water supply systems, HVAC systems, and technical pipelines to remove accumulated air during operation. If trapped air remains inside the piping network, it can reduce flow capacity, create noise, and affect overall system stability. For this reason, air vent valves play an important role in maintaining efficient and reliable operation.

Today, air vent valves are available in various designs and sizes to suit projects of all scales, from residential buildings to industrial facilities. Common performance requirements include effective air discharge, reliable sealing, durable materials, and clear technical specifications to ensure safe long-term service.

Watts air vent valves are highly regarded for consistent quality and strict manufacturing standards. Their design focuses on mechanical durability, reliable operation under a wide range of conditions, and compatibility with technical systems. Compared with many standard products on the market, Watts air vent valves offer higher dependability and meet demanding engineering requirements in real operating environments.

Operating Principle of Air Vent Valves

An air vent valve operates fully automatically based on the buoyant force (Archimedes’ principle) and the density difference between the liquid and air. Its main component is a float inside the valve chamber, linked to the vent orifice through a lever mechanism. The valve opens or closes in response to the water level inside the chamber.

• Normal condition (Valve closed): When the pipeline operates normally, and the chamber is full of water, buoyancy lifts the float to its highest position. The lever mechanism presses the sealing plug tightly against the vent outlet, keeping the valve closed and preventing leakage.
• Air release condition (Valve open): When trapped air enters the chamber, it displaces water and lowers the water level. The float drops under its own weight, opening the vent outlet. Accumulated air vents rapidly to the atmosphere.
• Reset condition (Valve closes again): After excess air is discharged, water refills the chamber. Buoyancy lifts the float upward again, closing the vent outlet and restoring the sealed position.
• Vacuum break condition (Pipeline draining): When pipeline pressure drops suddenly, such as during draining, the float falls to the lowest position and fully opens the vent. Outside air enters the pipeline to equalize pressure and help prevent vacuum-related pipe deformation.

Watts Air Vent Valve Product Line

To meet different technical requirements and system sizes, Watts offers a wide range of air vent valves with various configurations, sizes, and application ranges. Each model is designed for specific installation conditions, helping engineers and contractors select the most suitable solution for each system.

Series W-PQ21X-16T

The W-PQ21X-16T series is a small automatic air vent valve from Watts, designed for hot water and chilled water distribution systems. The valve features a compact structure, light weight, durable materials, and stable performance under high-pressure conditions. It is suitable for installation at high points in piping systems where continuous air release and reliable sealing are required.

Below are the key technical specifications of the W-PQ21X-16T series:

• Valve size: DN15 – DN25
• Body material: Brass HPb57-3
• Nominal pressure: PN16
• Temperature range: 0°C to 110°C
• Test standard: GB/T 13927-2008
• Connection standard: G thread
• Working medium: Water

Series 9101A

The 9101A series is a double orifice air vent valve from Watts, designed for large-diameter piping systems. The valve effectively releases accumulated air during normal operation while also allowing large-volume air intake and discharge during system filling or draining. With its robust construction and stable operating performance, the Series 9101A is commonly used in water supply networks, transmission pipelines, and large-scale infrastructure systems.

Below are the key technical specifications of the 9101A series:

• Valve size: DN50 – DN200
• Body material: Cast iron
• Nominal pressure: PN16
• Temperature range: −10°C to 120°C
• Design standard: EN 1717:2002
• Connection standards: Flanged to EN 1092-2 or ANSI B16.1
• Connection type: Flanged
• Working medium: Water

Series 9701

The 9701 series is a compact automatic air vent valve from Watts, designed for piping systems that require precise air control even under full pressure conditions. The valve features a robust construction, a stable float mechanism, and effective air discharge during continuous operation. These qualities make the Series 9701 suitable for water supply systems, HVAC applications, and technical systems requiring high reliability.

Below are the key technical specifications of the 9701 series:

• Valve size: DN15 – DN25
• Body material: Cast iron EN-JL-1040
• Nominal pressure: PN16
• Temperature range: -10°C to 120°C
• Design standard: EN 1717:2002
• Connection standards: NPT to ASTM B1.20.1 or BSPT to BS EN 10226

Toan Cau – Exclusive Distributor of Watts Air Vent Valves in Vietnam

Watts air vent valves meet strict engineering standards, prioritizing stable air release performance, reliable sealing, and long service life for water supply, HVAC, and technical infrastructure systems. The product range is clearly classified by size and operating conditions, helping engineers and contractors select the right model for each installation point.

In Vietnam, Toan Cau Building Materials Co., Ltd. is the exclusive distributor of Watts air vent valves, providing genuine products and transparent technical information. The company also carries hot water control valves, pressure regulating valves, pressure reducing valves, safety valves, and strainers – covering complete piping system needs. With more than 18 years of experience, Toan Cau is trusted for accurate product consultation and project-based technical support.