Safety Valve Correct Position 1

[kmic]

Hi, everybody
I have a system that produce Hot-Water in order to heat milk .
My question is where is the correct position of Safety valve in hot water line and why. I attached three files with three cases may have more than three.

CASE 1
In first case I place the safety valve at hot water outlet after the welded brazed heat exchanger and I follow the rule for hot-water boiler in central heating that place the safety valve at outlet of boiler .

CASE 2
I saw it from internet but I don’t know the reason and why place the safety valve at the line of filling water at suction line of pump.

CASE 3
In case 3 also i saw it from web plase the safety valve at pump outlet before welded brazed heat exchanger.

I don’t know which one is the correct one to choose.
Pls Advice.

 

[IRstuff]

Surely, one might start with the actual requirement? What is the safety valve supposed to do, and when is it supposed to do it?

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

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[BronYrAur]

The source of over-pressurization is the heat exchanger. If the heat exchanger becomes isolated or the expansion tank is somehow valved off, the thermal expansion will have no where to go. I would place the valve right after the heat exchanger BEFORE ANY SHUTOFF VALVES. For a boiler system, the relief valve is right on the boiler. Ideally, it would be right on the heat exchanger in your case; but, a plate-type exchanger has no connection for relief. I would put it immediately downstream of the heat exchanger.