There is a special type of check valve that prevents pistons or cylinder plungers from coming down and causing accidents. This is called a line rupture valve. When the line ruptures, the flow through the line rupture valve increases substantially, causing an increased pressure drop.
This in turn creates a stronger force on the ball, which will close immediately. Other special types of check valves are pilot-operated check valves and shuttle valves. A pilot-operated check valve allows flow in either direction by application of an external pilot pressure signal.
A shuttle valve permits free flow at the highest operating pressure. A hydraulic system can only function - as per requirements - by using valves. Thus, you should always look for the correct type of hydraulic valve to serve your intended purpose. Get advice and suggestions from DTA in order to select the appropriate hydraulic valve, in terms of size and function, that suits your application and your budget.
DTA has extensive expertise with hydraulic valves and carries a substantial inventory of hydraulic valves in different sizes, valve spool configurations and solenoid voltages. Remember Me. Username or Email. About Us Contact Us. Articles Plumbing. Next article - Soldering solutions make it easy ». Featured News.
Please leave this blank. Quick links. What next for oil? September 7, HVO potential — the evidence September 3, Designed by Red Box Stafford. This website uses cookies to improve your experience. Non-return valve is a term commonly used in industry and easily understood by the public. Simply put it describes devices trying to stop fluids returning back. Since industrialisation engineers soon realised the need to stop fluids flowing backwards, either to aid processes or to prevent damage.
They soon came up with ingenious designs to stop this, giving them a variety of different names amongst them non-return valves NRVs and check valves CVs. It is only in the 70's that there was a change in the meanings for both of these terms particularly when talking about water supply systems.
Separate standards were drawn specifically for water supply systems in the early 's, which defined higher performance requirements for these new protection devices — now referred to as check valves. So, when reference is made to the Water Fittings Regulations Byelaws in Scotland and backflow protection it is easy to understand why lay people could mistakenly think of non-return valves. A quick search of the internet will show that in Frank P Cotter is credited as to creating the first simple self-seating check valve that could be readily opened for inspection and repair.
His design ensured that the check valve element would remain reliable when subjected to vibration and transitional stresses — something that is a fundamental requirement in modern backflow prevention devices within drinking water systems. Non-return valves are used in systems where it is desirable to make sure fluids flow mostly in one direction, but may not be critical, for example in pumped systems such as heating circuits.
In terms of water fittings, performance testing carried out on NRVs is principally to make sure fluids predominantly do not flow backwards — as you might expect — and to make sure the fitting is water tight and does not leak.
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