bursting disks and prv's

[squidward]

Hey does anyone here use a bursting disc ahead of a pressure safety release valve? We suffered a ***** loss due to a bad safety ( neoprene seat r-22 and wf-68 oil are ok below 70 F) I got new Hanson safetys and saw available bursting disc assembly. A good idea i think, many good benefits, nobody upstairs wants to approve the use. Comments?

[chilliwilly]

Yes I know what you mean. I think they would rather damage the system than allow ***** to escape into the atmosphere.

To be honest I've only ever seen a pressure relief setup to vent into a cylinder. That in turn itself was under a vacuum. It was intended to receive about 500 lbs of R22, from three Isovel units. And have a glycol loop formed around it, and it's own small chiller to keep it cool enough to keep the ***** in liquid form.

This was back in the early eighties, and it never got any further than the receiver cylinder being craned up to the roof and then secured. With no plumbing whatsoever.

I suppose these days it would be part of the package and not as an extra. It was only a suggestion as it took so long to commision the job in the middle of winter. The customer didn't want their mainframe computers to be down for any longer than neccesary. As it took nearly four days to make the bubbles disapear from the site glass.

I think the prv device was just a metal bursting disc that just had a strainer surrounding it to catch any fragments. Then angled down to the floor.

[ICE/RUNNER]

We use Henry safety valve kits (a rupture disc and prv) on our units, they had proven to be highly reliable. They have prevented several releases of refrigerant due to degradation of the prv valve seat. When we have had systems vent the rupture disc assembly has also give us a visible indication that it been activated unlike a prv on its own.

[NH3LVR]

Rupture discs are well worth the expense. I recomend them highly. Sooner or later they will save you a lot of money.

[McFranklin]

The Hansen rupture disc assemblies are to indicate which relief valve has discharged. They are not stand alone safety devices. They will provide a hermetic seal to eliminate minute losses through the pressure relief valve. The Hansen RDA's are a one time use device. They reduce the capacity of the PRV (10% per ASME)
I would match RDA's and PRV, i.e. stay with Hansen since you have Hansen PRV, if you had Henry's use their RDA.
Verify the capacity reduction is acceptable with respect to your regulating agency.
If your release was due to an overpressure event, all a RDA will do is localize which valve opened.
If your problem is seepage through a valve, it will stop that.
And Hansen's literature says the RDA's are required when using their valves with halocarbon refrigerants.

[squidward]

Thanks Everybody, it looks like I'm going to get approval to use the Hanson Bursting disc and Hanson safeties. Our failure was due to neoprene seat degradation. Hanson has teflon seats. I'm also adding liquid level transmitter into receiver and tracking on plant computer.

[Grizzly]

Hi squidward.
You may like to consider these Henry PRV'S.
They have visual indicators on them.
follow the link.
They even, can come with a pressure switch gauge port.
To wire into a comp system to warn of refrigerant release.

http://www.henrytech.com/catalog/2010/h20-h21.pdf
cheers Grizzly