What is this valve on cold feed

[BobbyJoe]

Hi everyone, can you tell me what this valve is on the mains cold water feed and is it necessary to have thank you.

 

[ShaunCorbs]

Non return valve what’s the appliance?

 

[Deleted member 120897]

Looks like a verifiable single check valve, if it’s fitted, it’s usually warranted.

 

[BobbyJoe]

It is fitted on the cold drinking water pipe, is it a NRV or single check valve? and is there a difference in the two kinds thank you once again.

 

[ShaunCorbs]

To protect against back flow as it’s a drinking fountain

It’s a verifiable double check

 

[Deleted member 120897]

It is fitted on the cold drinking water pipe, is it a NRV or single check valve? and is there a difference in the two kinds thank you once again.

Check valve - there is a difference

 

[BobbyJoe]

Thank you for the replies and useful information it is much appreciated.
Next question is, where should the double check valve be fitted, on the cold-water feed pipe before or after the stopcock under the sink which would be 15mm in size or on the incoming mains pipe which has a T bar on it and is 22mm in size? Thank you

 

[Ric2013]

In flats, they sometimes put a check valve on the incoming supply pipe to each flat to stop upstairs water running back down to lower floors if the mains supply fails or is shut off.

But this kind of valve could be fitted for many reasons. Most commonly to stop backflow from a specific tap or appliance such as a washing machine. So the correct place to put it depends on why it was put there in the first place.

It is very rare for a check valve to be a problem even if it proved that it were fitted somewhere it is no longer needed.