Quote Originally Posted by Andy View Post
I have worked on some Gram plants in the past, they use a safety valve on all valve stations which is a check valve with a spring, releasing at a pressure just above the normal defrost pressure. These valves are live to the mains and cannot be isolated meaning you can never over pressure an evaporator. If you are wondering how you change them, it involves pumping out the systems and holding a vacumn until the valve is swapped out (uses nut and tail fittings on the valve).

I alway thought this was a very clever way to go.

Kind Regards Andy

We used to have this in our systems before (long before my time) still use it on the liquid line from pump pressure and back to the liquid separator (think they open at 5 or 10 bar, can't remember)

The ones I have seen on valve stations are mostly cut out and welded shut. probably after the second time they started leaking

the ones we use are Ermeto RHD 10L.

Now that stainless is being used more and more in the corrosive exposed parts of the plant, maybe it wouldnt be a bad idea to start using them again


Cheers