{{unreferenced, date=August 2009
Pneumatic non-return valves are used where a normal
non-return valve
A check valve, non-return valve, reflux valve, retention valve, foot valve, or one-way valve is a valve that normally allows fluid (liquid or gas) to flow through it in only one direction.
Check valves are two-port valves, meaning they have ...
would be ineffective. This is for example where there is a risk of
flood water entering a site but an equal risk of pollution or a
chemical spills leaving a site and polluting the environment.
Pneumatic non-return valves are installed below ground and can be used to pneumatically lock the non-return valve closed thus containing a site in the event of a spill.
It is common practice to lock sites using pneumatic non-return valves during the loading or transferring of chemicals or hazardous waste. Pneumatic non-return valves have a longer service life when compared to
pneumatic bladder systems.
Valves
Environmental protection