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Pounds per Square Inch for Pressure Release Valves

Hi,

I want one for my still. I have found one I can use by drilling my 4" TC plate and fitting there. It comes preset to 0.2 MPA that is 30lb per square inch. It can be adjusted bu I am not sure by how much... so lets just say worst case it's 30lb per square inch. That seems a lot of pressure to me.. better than nothing but all the same.

Does anyone have any thoughts or suggestions?

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Comments

  • The pressure relief I have on my kettle proper (not jacket), is 5psi, 0.5bar.

  • yes, i was thinking i needed 5psi... if this one starts at 30 i cant see it going down to 5psi. I have a 5psi one but its threaded so i would need to drill and tap my SS 4" plate. or find one that has a nut and washer etc.. not as easy as it sounds!

  • You should have national standards that apply to both pressure vessels AND pressure relief valves.

    That is, even if your vessel doesn't require a PRV, if you install one you now need to comply with the national regulations for PRVs. Here in AUS, the National Workplace Health and Safety Act (Legal compliance is required) references these various other AUS/NZS standards.

    AUS/NZS Standards on their own are not a legally enforceable document but when they are referenced by an Act then they become legally enforceable.

    FYI on an aside, like Europe, here in Australia and New Zealand we follow IECEx standards rather than the ATEX certification model.

    With that in mind, find your equivalent pressure vessel and pressure safety devices standards for the best guide. If you can't or don't understand them, find an engineer who does.

    For us here we MUST have these things specified by a certified engineer as every vessel, conditions, environment etc is unique and must be accounted for.

    Another good example of how unique these calculations are, in some situations venting into the room is acceptable. In other situations the vent must be external, and the vent must not be in certain locations and it must be a certain distance from the roof of the building and a certain distance frlm all manner of other things for all manner of reasons.

    Then, the sizing (length, bends, diameter) of the vent piping and everything from the pressure vessel to the outlet of the vent are all accounted for and specified. Nothing is left to chance. Remeber, we are not experts in this field but we can go to prison if we think we are and we get it wrong, in the event of a catastrophic failure. That's why we employ a an engineer certified for that l line of work.

    There's no simple solution for the commercial operator.

    I hope that helps, a little.

    Cheers,

    Mech

  • it doesn't help, not even a little bit :))

  • @needmorstuff said: it doesn't help, not even a little bit :))

    I got my SD 380L boiler back when it was thought that never having a valve or other way to seal the still was safe enough... after one fatal distillery accident where the supposed cause was blockage in the condenser, that was no longer a safe assumption, and a $100 PRV of 0.5-1.0 was the new norm on ALL still kettles...

    You can get the official SD one, or an eBay/Aliexpress one, I suggest the 2" TC one only, and if you are scared of the flammable vapors, you can pipe it outside with 2" TC pipe... I wanted a couple, and put an offer on these on eBay from China and got them for a few dollars less for buying 2...

  • Interesting. I didn't realise it was available on 2". Just so long as you don't use it on the oil heating section of a bain marie its a great solution.

  • edited February 6

    Pressure Relief Valve 2" TC x .1 MPA @ StillDragon Australia

    Maybe i should be buying them from eBay too.

    StillDragon Australia & New Zealand - Your StillDragon® Distributor for Australia & New Zealand

  • So .1 MPA is like 15psi... Is that also ok? I'm talking pot still pressures.

  • buy 1000 of them and they are only $10...
    Stainless Steel Sanitary Clamped Pressure Vacuum Relief Valve for Brewing @ Alibaba

    Just think how safe you will be! =))

  • I'd have 50 years worth of stock.

    StillDragon Australia & New Zealand - Your StillDragon® Distributor for Australia & New Zealand

  • edited February 5

    15 psi is about 1 bar overpressure, its equivalent of water boiling at 120 degre Celsius. It must be enough. Thats eqivalent of 10 m of water. Thats 100 plates running at very low speed with 100 mm of product ( or water ) in each plate. Dynamic effects will apply so running it more than in idle will mean maybe 30 plates, but thats just a guess. If you are unsure Please put the whole still to the watersystem, it will give you about 5 bars (70 psi or so ) and the valve should open. If you really want this safety Please do it right. The outlet of the valve, dont let it point in the direktion of a flame, face or something else that does not like steam at 120 degree celcius :) . Maybe down in a drain or in a pipe to the cieling. Of course you could put the valve under the water / alkohol level as well but i would not do that, it could clogg , liquid has less heat and it could also run dry. The mechwarrior mentioned this above indirectly. But steam in the face is never good. However an explosion is almost allways worse, so even ignoring what we wrote you are safer with the valve.

  • When I'm asking is 15psi ok, I mean is it too high for a pot still...

  • I reckon that question has been covered fairly well already, asking the same question is likely to get you the same answer.

    StillDragon Australia & New Zealand - Your StillDragon® Distributor for Australia & New Zealand

  • 1 bar for a jacket and .5 bar for the kettle

    StillDragon North America - Your StillDragon® Distributor for North America

  • Thanks Smaug, appreciate that.

  • Is it hobby or commercial?

    For commercial, the valve is sized based on the max available power, size of the vessel, content %abv. The valve must discharge to external of the building but under a few minor circumstances it may (but I wouldn't recommend it) be discharged to inside.

    Are you commercial?

  • Yes but very small scale. 50litre pot still. Charge 30%,3kw

  • With a pressure gauge you can tune ours to the max pressure rating or less.

    StillDragon North America - Your StillDragon® Distributor for North America

  • Wondered why more folks didn’t just use sanitary bursting disc.

  • Yes, but then the pressure gauge falls under the standards and must be certified, calibrated and maintainted, tested/recertified as compliant every 6 months or 12 months depending on your local legislation.

    @needmorstuff , for an operation of your size it would take an suitably qualified/certified engineer about 5 minutes to tell you what you need to know, plus the cost of the report.

    It would be cheap as chips for the 100% certainty that what you're doing is meeting at least the minimum legal requirements.

    For me and many larger facilities our engineering costs would exceed your distillery costs.

    What have you got to lose?

    Ultimately it's your business and your risks to take. When and if the risks have the potential to involve employees, family, friends or businesses/ neighbours then you should consider the risks you are taking without consulting them. That's why these laws exist, to remove the decision making process from your hands.

    I've said enough on this post.

  • @grim said: Wondered why more folks didn’t just use sanitary bursting disc.

    what would happen if you took disc of aluminum foil and clamped it in the gasket of a 2" fitting on top top of the still, and had a pipe going outside, or into a bucket of water inside (you could see leaks) and it would mitigate alcohol going into the air...

  • @CothermanDistilling why aluminum foil? Aren't you just hard plumbing a blow off tube? Control max pressure by water immersion depth...

  • @grim said: Wondered why more folks didn’t just use sanitary bursting disc.

    These are brilliant items and highly accurate. Maybe because it does not look as cool as a vent. Maybe because if piped to the outside you would not notice the burst unless you had instrumnentation in place. Maybe because its a final break and would need to be replaced whereas a vent starts as a gentle leak and the closes aferwards.

  • @Unsensibel said: CothermanDistilling why aluminum foil? Aren't you just hard plumbing a blow off tube? Control max pressure by water immersion depth...

    a readily available material that seals, and bursts with some regularity. thinking on the vent tube, would need to allow for some serious suction too... maybe some 8' sections of 2" glass on the wall...

  • Bursting discs are one off and quite expensive. You can get reusable ones but they are very expensive.

    StillDragon Australia & New Zealand - Your StillDragon® Distributor for Australia & New Zealand

  • @CothermanDistilling said: a readily available material that seals, and bursts with some regularity. thinking on the vent tube, would need to allow for some serious suction too... maybe some 8' sections of 2" glass on the wall...

    If we're talking about PRV, why would you protect for vacuum? During a run, I don't know when you would encounter a vacuum. However, kettle plus been to floor should give you 5' easy

  • A vacuum is encountered when the vessel and or its contents which are under pressure and undergoes cooling

  • edited February 7

    While a vacuum break is critical in both places, it's especially critical for a steam jacket, which can easily go from being very hot, to very cold quickly. Imagine you accidentally had the steam jacket on, with an empty kettle. Ooops. Turn off the steam and proceed to spray down the kettle with cold water from a hose, or pump in cold wash.

    Boom.

  • I've seen 100,000L silos collapsed due to the absence of a vacuum break.

    Hot contents just emptied (just like a still), well intentioned but ill informed still hand starts the CIP on the still, flushing with cold water and instantly BOOM!!!.

    You now own a very expensive pile of useless junk, that was a moment ago your functional art, the financial driving force of your empire, your still is now useless.

  • edited February 7

    Most jurisdictions require PRVs with specific approvals, in the US it would be ASME rated and stamped pressure relief valves (eg. Apollo valves). I mentioned bursting disk above, you can find these in jurisdiction-approved flavors. While a non approved valve might work in exactly the same way, recognize that the price you pay for these valves has nothing to do with the actual valve, and everything to do with the testing and certifications required for liability lawsuits. You aren't paying for the valve, you are paying for the lawyers and engineers that stand behind them.

    Anyway, nice thing about bursting disk is that they are sanitary, and for the most part aren't going to be damaged by CIP. They should probably be replaced regularly, but that said, they have the advantage of fitting standard triclamp, so they are very easy to retrofit. I seriously doubt the reliability of even Apollo valves subjected to harsh CIP chemicals. Even with teflon seals, they may not stand up to the incredibly harsh conditions. These should probably be replaced regularly as well.

    What I really like about bursting, they don't reset. Meaning, if there is an overpressure situation that releases the vent to protect the system, you need to fix the root cause.

    However, it's true, they ain't cheap. Little tri-clamp gasket burst like this one is easy a few hundred dollars.

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