Is this an Isolator ?

[Mark 9002]

I'm going to be changing the noisy Ball cock V/V in my CWST for a more silent flowmaster type fill V/V. I had my head up in the tight loft space just to give the job a coat of looking at before I give it a go. I know this sounds a bit obvious, but the picture shows a fitting on the mains supply just before the tank connection to the old V/V I'm going to replace, and Just want somebody to confirm what it is. I know it looks like an Isolator, but I've never seen one like this before. It looks a bit more substantial than your run of the mill isolator V/V. I don't want to try turning the screw on top just yet incase I get the dreaded dribble of water start coming out of the top before I'm ready to do the job.. Is it just an old type of isolator or some other type of fitting ????????

 

[mogget]

It's a heavy duty Ballofix isolator, they're actually very good and on the more modern types at least the screw will only turn a 1/4 turn and will not go round and round.

 

[Mark 9002]

Thanks Mogget.
Now I know. I'll a spare on hand when I do the job Just in case. That ones been there 25 years