Where and why are non-return flap valves used?


One of the explosion protective systems are non-return flap valves also called explosion isolation flap valves. Here are a few words on how they work and where they are used.

What isolation flap valves are installed for?

The certified isolation flap valves are used for explosion isolation. In other words they prevent the explosion from spreading along the pipelines by cutting the explosion off from the rest of the pipeline system. In effect, the flame and the pressure of explosion do not reach the production hall or the processing machines. The explosion isolation flap vales protect both people and entire plants from danger of explosion. The flap valves, aslo called non-return valves, are one of the ATEX protective systems, certified systems which aim at explosion protection in accordance with the ATEX directive.

How do the flap valves work and where are they installed?

The non-return flap valves are installed on pipelines – both on the dirty (dusted air) and clean (filtrated air) side of a dust collector. One must follow the strictly defined distance of the flap from the protected tank (a dust collector, a silo etc) so that the valve works properly. The valve we offer can be installed in both horizontal and vertical position.
When an explosion occurs, the shock wave shuts the flap, which automatically locks itself (it cannot be opened except manually) preventing the explosion from spreading into other parts of the dedusting system – the explosion is isolated, both people and facilities are safe.

What should you remember about when selecting and assembling the non-return flap valve?

When selecting a valve and planing its assembly, we need to make sure whether its ATEX certification is valid and what explosivity class it is designed for. It is also very important to read the User Manual and follow the rules of the allowed distances at which the valve can be mounted and the number of bends (elbows) that can be used between the protected tank (dust collector) and the valve. Another crucial thing is to know the direction of the air flow inside the installation and to determine the direction of the possible explosion. Only a correctly installed flap valve is going to work and effectively protect your plant.