Question 1

What is an air release valve and how does it work?

Accepted Answer

An air release valve is a pipeline component that continuously releases small air pockets that accumulate at pipeline high points during normal operation. It uses precision orifices and floating ball mechanisms that automatically release air while maintaining a liquid seal, preserving hydraulic efficiency and preventing air-related issues such as reduced flow capacity, increased pumping costs, and potential water hammer.

Question 2

What is the difference between an air release valve and an air vacuum valve?

Accepted Answer

Air release valves continuously release accumulated air during normal operation via small orifices, while air vacuum valves admit atmospheric air into the pipeline via large orifices during drainage, pump shutdown, or line break conditions to prevent vacuum formation that could collapse pipes or damage equipment. Both functions are essential for proper pipeline design.

Question 3

When should I use a combination air valve?

Accepted Answer

Combination air valves integrate both air release and air vacuum functions in a single compact unit. They are ideal where space constraints limit installation of separate components, and are commonly used at pipeline high points in water distribution systems, pump stations, treatment plant piping, industrial process lines, and irrigation networks where both functions are required.

Question 4

How do I size an air valve correctly for my pipeline?

Accepted Answer

Proper air valve sizing depends on several key factors: pipe diameter and length (which determine the volume of air to be released or admitted), system pressure, flow velocity, pipeline profile (high points require air release valves, low points need vacuum valves), and water quality (corrosive fluids may require stainless steel construction). SHIELD engineering team uses industry-standard air valve selection charts to ensure optimal sizing for your specific application.

Question 5

What materials are available for SHIELD Air Valves?

Accepted Answer

SHIELD Air Valve Series AV is available with body and cover materials in cast iron, ductile iron, and stainless steel. Float materials include stainless steel, polypropylene, and UHMWPE. Seat materials include EPDM, NBR, Viton, and PTFE. Stainless steel options are recommended for wastewater and aggressive fluid applications.

Question 6

What size range and pressure rating does the SHIELD Air Valve Series AV cover?

Accepted Answer

The SHIELD Air Valve Series AV covers a size range of DN25 to DN300 (1" to 12") with pressure ratings of PN10, PN16, and Class 150. The working temperature range is -20°C to 120°C. Design standards include AWWA C512, ISO 4126, and EN 1074, with testing per API 598, ISO 5208, and EN 12266-1.

Question 7

Where should air valves be installed in a pipeline?

Accepted Answer

Air release valves should be installed at pipeline high points where air pockets naturally accumulate. Air vacuum valves should be installed at pump discharge lines, transmission mains, storage tank inlets and outlets, and any location where vacuum conditions could occur during system operation or maintenance. Proper air valve installation at high points is critical for optimal performance.