Air Valves for Major London Infrastructure Upgrade

It was our pleasure to supply three-function combination air valves to sites across London for use in a major infrastructure project, ensuring optimal performance of pipelines and preventing potentially damaging accumulations of air and vacuums within pipe systems.

The Problem

Air valves are the unsung heroes of pipeline management, ensuring optimal hydraulics and minimising energy consumption. Uncontrolled accumulation of air within pipe systems can result in increased head loss, reduced pumping efficiency, corrosion and cause potentially catastrophic transients resulting in pipe failure. Air naturally forms from turbulence-inducing components such as pumps, valves and pipe fittings (e.g. bends and tees), poor joints and inherently from the conveyed fluid itself.

To the contrary, when the pressure of the pipeline falls beneath atmospheric pressure, vacuums can form. Sudden changes in velocity can occur when a pump abruptly stops, a valve closes quickly or drains sections of the pipeline without controlled air ingress, potentially resulting in vacuum-generating conditions. Under such conditions, pipes could implode and/or fail, resulting in media release.

During rehabilitation works to underpasses across London, there was a requirement for robust and reliable air valves to provide protection from the aforementioned effects of transient pressures, water hammer and air accumulation in pipelines, while also optimising system performance.

The Solution

T-T Flow supplied 64 plastic three-function plastic combination air valves rated to 16 Bar, delivering the efficient management of air over a long life thanks to the lightweight single chamber design, aerodynamic full-bore body and dynamic sealing preventing leakage in low-pressure conditions.

Air valves are self-acting hydro-mechanical devices that maintain a balanced system through the controlled intake and discharge of air. Generally, they have three overriding principal functions, also known as combination air valves. Firstly, the discharge of bulk air during the pipeline filling or charging phase, secondly the bulk intake of air during the pipeline draining or discharging phase, and thirdly, the controlled bleed of smaller pockets of accumulated air in the valve body during the operating phase.  

Proven Aquabrake® air valves from T-T boast an additional innovative safety principle of protection from anti-water hammer through a non-slam surge prevention system. This is deployed when the approaching water column exceeds a specific velocity, thereby avoiding the valve suddenly slamming closed.

T-T offers custom air valve variants including anti-shock air valves, anti-slam valves, inflow only, outflow only and those suitable for underground and submerged installation.  Pressures up to 64 Bar/ 928 psi can be catered for and in various materials from coated iron, stainless steel and aluminium bronze for offshore environments.

Selecting the correct air valve variant and positioning is critical in ensuring system stability and optimal performance. Utilising the latest hydraulic analysis software, T-T Flow engineers are available to offer advice on correct air valve selection and positioning. Just give our team a call on +44 (0)1630 647200 and we will be happy to help.