Relief valves

Not sure if asked before, but what methods & types of relief valves are installed on refrigerant side thermosyphon oil coolers, oil drain pots, pumped liquid lines.
Do you vent to atmosphere, internally.
Mare reliefs designed for liquid.

Thanks

On our systems we vent internally.
-Oil drain pots we use danfoss OFV 25 as a vent back to the LP drum during heating operation
there is also a Ermeto RHD 12L (5 bar cracking pressure) that vents back to the LP drum
http://www.parker.com/parkerimages/e...VALVES/RHD.pdf

We use this RHD on all lines where there is a danger of trapping cold liquid.

The thermosyphon, last one I remember was protected by the SFV on the receiver as there was isolating valves only on the liquid line, and no isolating valve on the return line back to the top of the receiver.

if there had been valves on both lines, I would have preferred to use a danfoss OFV type valve back to the receiver.

Thanks Tycho,
With OFV valves do you somehow lock or tag valve so it can’t be closed?
With thermosyphon, if you empty 1 you have to empty all.
We recently had one where tube failed on S&T, leaking refrigerant into oil system when off, unusual, but possible.