Cork pressure relief

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shadylane
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Cork pressure relief

Post by shadylane »

How effective is a cork for a boiler pressure relief valve aka PRV :?:
What diameter cork, would be a good place to start experimenting
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Re: Cork pressure relief

Post by RedwoodHillBilly »

shadylane wrote:How effective is a cork for a boiler pressure relief valve aka PRV :?:
What diameter cork, would be a good place to start experimenting
Better than nothing. Myself, I use a steam rated PRV or a PRV/VRV, but to each their own.
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shadylane
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Re: Cork pressure relief

Post by shadylane »

I also use a steam rated PRV.
Some folks are using a cork, and I was wondering how effective they are.
Now I need to find a couple corks and test them.
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thecroweater
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Re: Cork pressure relief

Post by thecroweater »

Shady didn't you post a picture of a corked manometer a few years ago?
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ShineonCrazyDiamond
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Re: Cork pressure relief

Post by ShineonCrazyDiamond »

2" I would be interested in. I am going to do a 2" tee to the thumper, cork on top.
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Re: Cork pressure relief

Post by ShineRunner »

I run a thumper and boiler with 2” tee, very much like MCH’s design. I’ve had my cork stopper pop up a little while using it for steaming corn.

Got mine here: https://www.onlinesciencemall.com/produ ... 7349363398" onclick="window.open(this.href);return false;" rel="nofollow

I’d be interested in seeing the test numbers compared to your manometer..

SR

Edit: when corks start getting that big, I couldn’t find any single piece corks. My first corks were laminated horizontally and started to fall apart over time. When I bought these, I talked to the sales rep and they confirmed that they are laminated vertically, and use no glue. They are pressed together only. Because they’re laminated vertically, the pressure from being inserted into the top of the tee holds it together...
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bluefish_dist
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Re: Cork pressure relief

Post by bluefish_dist »

I would be concerned about the cork actually releasing. They swell up a lot under heat and vapor. A spring type pressure relief is much safer. Most pressure reliefs are simply a plate with a really light spring. The trick is adding a path to contain the vapor after release.
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Re: Cork pressure relief

Post by zach »

A bench test could be done with a manometer to determine the lifting pressure of the cork.
The repeatablity of the result would depend on if the depth the cork was inserted into the opening was consistent.

I wouldn't use a cork because there are better options like a manometer. The manometer could be as simple as a CSST tube into reservoir of water with a depth greater than the anticipated pressure in the boiler. 1 psi will produce a water column of approximately 27.6 inches .

I work in an industry where the prv's are required to vent into a water tank to prevent atmospheric release of toxic gas. I would do the same if I had a boiler that required a PRV.
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thecroweater
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Re: Cork pressure relief

Post by thecroweater »

Exactly my point, if the prv doesn't gas off to a vented area or a reservoir then it may just be creating an extra hazard.
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Kareltje
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Re: Cork pressure relief

Post by Kareltje »

Indeed! The release pressure of a cork depends on how hard you slammed into its place. As long as this pressure is below the exploding pressure of a vessel it is safe, apart from the vapours that are released.
I would rather use a marble or a set of marbles, venting into a safe space. That can be calculated and regulated.
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shadylane
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Re: Cork pressure relief

Post by shadylane »

The round hole, I'm plugging with a cork is 21mm.
That's a tad smaller than 53/64" and a little bigger than 13/16" :lol:
I have both rubber and a real cork that fits the hole.
When the corks are gently seated I can blow hard enough to pop them out.
Damn, I forgot blowing hard will make your ears hurt :lol:
Guess I need a stronger source of hot air than I can supply
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shadylane
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Re: Cork pressure relief

Post by shadylane »

thecroweater wrote:Exactly my point, if the prv doesn't gas off to a vented area or a reservoir then it may just be creating an extra hazard.
And that's a fact, when venting anything more volatile than water :thumbup:
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shadylane
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Re: Cork pressure relief

Post by shadylane »

All the tests were done with dry, cold air.
I hammered a good quality natural cork in the hole and it took 36lbs air pressure to blow it out.
The rubber cork withstood almost 70 pounds pressure before it popped.
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bluefish_dist
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Re: Cork pressure relief

Post by bluefish_dist »

I bet if the natural cork had steam behind it it would have been even higher.
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Soft batch
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Re: Cork pressure relief

Post by Soft batch »

Doing some quick math and assuming a perfect seal, the marble on top may be a better low pressure safety valve for a boiler/thumper.

Assumptions:
1/2" ID pipe
9/16" marble @ 4.56 grams = .5 PSI
3/4" marble @ 17.0 grams = 1.9 PSI

I remember reading some time back where someone made a bed of silicone for the marble to rest on to improve the seal.
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Re: Cork pressure relief

Post by The Baker »

I would not use cork, it could jam.

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Re: Cork pressure relief

Post by acfixer69 »

30 bucks you can get a spring lifted steam rated PRV 5 pis and be done with the drama and worry. Give it a lift couple times a year and you are covered. I like shadys manometer though be cool to know along the run for reference.

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