Leaking T&P Valve Question

debtfreeian

Hi there, I have a t&p valve similar to this one below. It's leaking at the nut on the side. Can someone tell me what that nut is for? More for info as I have a plumber coming tomorrow so assume we'll replace the part. I just don't see that nut on many of these valves so curious.
https://www.unventedcomponentseurope.com/redring-pressure-temperature-relief-valve-97392033.html/?utm_source=Google%20Shopping&utm_campaign=Copy%20Unvented%20Components%20Europe&utm_medium=cpc&utm_term=3137&gclid=Cj0KCQiAhs79BRD0ARIsAC6XpaVv_vSgmZ9_X5GrcCOzOryiOSnu8-_REmbBZgGCI9wdTSH0-tN6Q7QaArTiEALw_wcB

Homer_home

Which nut there's at least 3 of them?

Jeepers_Creepers

The good news is that I know which nut he is referring to.

The bad is that I haven't a clue what it does.

It looks like an isolator - ie give it a quarter-turn and it closes off the valve - but it also looks as tho' it has 'something' in the centre of that 'wing'?

Haven't a scooby. Try emailing Redring? And then please come back :-)

Homer_home

If it's the thing that's not a nut in the slightest then it's a discharge valve (a safety device)