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I'm building a new boiler, and have been asked why I don't use a pressure relief system.
My still (a ponu) is open to the atmoshpere, so I wonder, do I need one? Is it saver? How do you build one?
A new item to me, so a lot of questions, and new things to learn

I use one, though I think I'm in the extreme minority. I read the same thing on this forum all the time, It's a open system why would I need a pressure relief? Well it's a open system right up until the time it gets plugged, then you have a bomb. The likely hood of you ever having a problem about 0, but why not have a backup? It only costs 5-10 bucks to buy one and if you can build a still you can install one on your boiler.

as long as you can pass the same or more lbs.of steam per hour then your boiler can produce, you are fine.
more relief or back up relief is never a bad thing.

i got a 3 " collumn packed with copper scrubber. I never in the world thought i would have a problem and need a relief valve. The keg says right on it "do not exceed 60psi" I think it was 60? but anyway, I could never see something plugging and building even half that pressure. Maybe if yer stillin on the grain?

you could use a coffee machine over pressure valve, they are small screw into a simple thread nut.

but i think they "release" at about 22 - 25 psi, even that might be to high as the gas would come hissing out under a fair amount of pressure and if naked flame "BOOM!!"

you would need to ensure it "vents" away from flame....... and maybe into a jug of water etc to knock down the ether....

it's an interesting idea.... like MK said would take a fair amount of goop to plug one fully and not have it spew it out pretty quick so i am not sure it's worth installing

rubber duck wrote:I use one, though I think I'm in the extreme minority. I read the same thing on this forum all the time, It's a open system why would I need a pressure relief? Well it's a open system right up until the time it gets plugged, then you have a bomb. The likely hood of you ever having a problem about 0, but why not have a backup? It only costs 5-10 bucks to buy one and if you can build a still you can install one on your boiler.

This is a good point, ducky. I could put something actually usefull in the hole I had a thermometer in.

rubber duck wrote:I use one, though I think I'm in the extreme minority. I read the same thing on this forum all the time, It's a open system why would I need a pressure relief? Well it's a open system right up until the time it gets plugged, then you have a bomb. The likely hood of you ever having a problem about 0, but why not have a backup? It only costs 5-10 bucks to buy one and if you can build a still you can install one on your boiler.

Ok, sounds reasable.
Can you show me a pic, how it looks like.

The only pressure i can think of is a thumper where the outlet is submerged a few inches underwater in the thumper. 4" Of water = 0.14 Lbs/sq". A well sealed system will cater for low pressure. High pressure should never happen and a high pressure relief valve is a symptom of a big problem that shouldn't be there in the first place.

I installed this little suckers, they are used normally as hot water pressure relieve.

I took them apart and replaced the spring with a softer one, than calibrated to 15 PSI.

One is for pressure the other reversed is for vacuum.

The instrument never shows any pressure during the runs.

That vacuum break is a good idea Rednose. Your set up is similar to what I have on my keg still.

The only way I can think of to get a pressure build up would be to have something fall on the worm and kink it, or if a guy was running on grain. Weird stuff happens all the time, just look at the pictures of the unvented keg rim. I guess I'm just super cautious, I figure if something bad can happen it will happen to me.

RD

I use a water column of 12" for a safety relief (.75 lbs of pressure). pretty much a 12" deep P trap coming off the boiler filled with water...Pressure gets to high it will blow the water out of the tube and release pressure (as well as vacuum, if needed)...

A reflux still is open to the atmosphere...no measurable pressure unless your'e a quantum physsyst. A pot still may experience a tiny pressure accordin to the thumper and there's all it is.

I get a little confused, but maybe I discribe my rig.
Copper boiler, a helmet which fits loose in the boiler (breaddough will clos it) on top the ponu.
I can place an element in the helmet, something like this maybe:http://www.ebora.nl/producten/Appendage ... -10.00.pdf
This is totaly new to me, so every suggestion is welcome, and pics even more

I don't have a relief valve, but I do have a 15psi pressure gauge (it was free) so I can monitor things. In over 40 runs I have never seen the needle tick even a bit, even with a full thumper (outlet 6-8" under liquid). Not to mention, if the outlet got plugged you'd notice right away ("why is my still so quiet...?").

Pressure can only build up to the point that your weakest link can handle. If you are sealing with bread dough, that pressure is very low, and even if your seal "fails" it certainly won't be catastrophic. I've done a few tests with my own (non-still) stock pots, and a bread/water mixture never held past 1-2 PSI, even when think and even. The natural irregularities in such a seal prevent a really bad failure (eg, the lid flying off), the thinnest part of the seal just pops (and maybe whistles), then there is no more pressure.

While I don't think you'd ever really need a relief valve on a dough sealed still, it would be really easy to put one on if you are worried about it.

I keep a pressure relief on my ponu's... If that outlet tube going to the condenser (secondary coil) plugs she'll start building pressure. I've done over 50 runs and it hasn't happened (or even come close) yet, buy why take chances.....