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Offline DGdistill  
#1 Posted : Tuesday, June 12, 2012 1:08:35 PM(UTC)
DGdistill


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"Hi All,

Has anyone installed any pressure relief devices on a brewhaus still? Anyone have any idea what the pressure/vacuum tolerances are on the PSII high capacity with 15 gal premium kettle? I figure that normal operating pressures/ vacuum must be far far lower than what would damage the still, but I thought I'd ask.


I'm thinking this valve might work:
http://www.grainger.com/Grainge...-Relief-5DLZ3?Pid=search

Does 15psi seem like the right pressure range? I'm not sure if it is bidirectional either, I'll have to do some more digging. If you have any suggestions, I'd be grateful.

Thanks,
Dave"
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Offline muadib2001  
#2 Posted : Tuesday, June 12, 2012 1:16:07 PM(UTC)
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Pardon me, but I thought there was no pressure of any kind in a still. I thought it was an open system.

There might be pressure in the coolant pumps (if present), but that's different from the main still.
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Offline DGdistill  
#3 Posted : Tuesday, June 12, 2012 1:19:48 PM(UTC)
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"Thanks for the reply Muadib. Perhaps I should clarify.

Yes, there SHOULD only ever be very minimal pressure and/or vacuum in a properly run still.

However, there are many ways in which pressure and/or vacuum could accidentally build up in an improperly run still. Especially if one is using a valve to directly control reflux ratio (rather than coolant flow or heat input), which is something I am thinking of implementing. For example:

1. column could get clogged
2. needle valve could get stuck
3. inattentive operator could leave valve in inappropriate position
4. ???"
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Offline muadib2001  
#4 Posted : Tuesday, June 12, 2012 1:35:48 PM(UTC)
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True statements.

As I am unfamiliar with reflux stills and their operation, I will recuse myself from this thread.
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Offline John Barleycorn  
#5 Posted : Tuesday, June 12, 2012 2:03:50 PM(UTC)
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"
Originally Posted by: DGdistill Go to Quoted Post
Especially if one is using a valve to directly control reflux ratio (rather than coolant flow or heat input), which is something I am thinking of implementing.
You might want to re-think that design of yours.

Sounds like you want to covert to a VM or LM? In which case the column condenser is open to the environment. So you should never have any pressure build up (beyond the normal vapor pressure).

> 1. column could get clogged

That would indeed be bad. Highly unlikely, but bad. If you're truly concerned with this you'll need to put that relief on your boiler. Otherwise, you won't be addressing this scenario.

> 2. needle valve could get stuck

Again, if a closed valve would cause your design to explode due to excessive pressur, you have an unsafe design.

> 3. inattentive operator could leave valve in inappropriate position

Valves aside, there's no manner of design that can match wits with the boundless stupidity of some select individuals. Do yourself a favor and keep them away from your rig. :)

Take a look at the VM/LM designs on HD and study the placement of the column condenser and the valves. I'm pretty confident with a few nips 'n tucks to your design you can meet your requirements without the need for a pressure relief valve.

--JB"
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Offline DGdistill  
#6 Posted : Tuesday, June 12, 2012 6:50:50 PM(UTC)
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"Hmmm,

I get that a pressure valve shouldn't be necessary if all diligence is used. However, the nature of life is that people make mistakes. I am used to working in very complicated situations with extremely smart people. Mistakes get made. Mistakes get made even though EVERYONE is paying absolute attention at all times (or we're supposed to).

A pressure relief valve seems like it would be an easy thing to add. I know the adding part would be easy. And I know where I would want to put it (on the boiler ).

The part I'm having trouble with is finding a good valve that relieves vacuum and pressure and is heat resistant and has an appropriate range. Does anyone have any thoughts? Does the original linked valve above seem like it would work? Does anyone know the vacuum and/or pressure resistance (even very approx.) of the kettle? Anyone want to guess, and explain the basis thereof?

Finally, BarleyCorn, thanks for the suggestion to look at VM and LM designs. I am indeed looking to modify my still to VM. I still think it's possible to exceed the pressure/vacuum limits of a well-designed still accidentally. Likely? Well, maybe not.

Cheers,
Dave"
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Offline John Barleycorn  
#7 Posted : Wednesday, June 13, 2012 2:14:22 AM(UTC)
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"Dave,
Originally Posted by: DGdistill Go to Quoted Post
I am indeed looking to modify my still to VM.


Someone on this forum had a tri-clamp flange added to the top of the column (above the cooling tubes where the bung is normally located). I'm not sure who did that though, but you might be able to search for the thread ... I don't remember if there were any pics As I recall, he did it so he could just use a standard sanitary cap rather than the bung/thermometer.

In any case, you could potentially do something similar and attach a (removable) condenser head for your VM (and simply leave the existing cooling tubes unused). Also, a good quality SS valve can be placed between the column and the existing product condenser ... and you would have your VM. Provided you leave the new condenser open at the top, I don't see any safety issues with something like this.

Just out of curiosity, what's the motivation for changing from CM to VM?

--JB"
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Offline DGdistill  
#8 Posted : Wednesday, June 13, 2012 4:49:59 AM(UTC)
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Thanks for the advice BarleyCorn. Regarding my motivation, well that's a tough one. Restlessness? Unwillingness to leave good-enough alone? Curiousity? Grass-is-always-greener-on-the-other-sidedness? Something like that.
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Offline John Barleycorn  
#9 Posted : Wednesday, June 13, 2012 5:08:24 AM(UTC)
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"You just have that itch that needs some scratching. I completely understand ;-)

Good luck. Post some pics when you get things set up.

--JB"
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Offline heeler  
#10 Posted : Thursday, June 14, 2012 2:35:43 AM(UTC)
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Gents, still unsure the porpose and functionality of a pressure relief valve on a still????? If you hold back pressure in the boiler would'nt that hold back the vapors which is where your likker is?? Dont you WANT the vapors to rise and condense soas to condese back into a liquid??? Not to mention the danger of excess pressure buildup ---I know the pressure relief valve will take care of that. Curious to learn the benifit of such a thing.
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Offline John Barleycorn  
#11 Posted : Thursday, June 14, 2012 4:46:45 AM(UTC)
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"Hi Heeler,

We were discussing a pressure relief valve v. a regulator or check valve -- so it doesn't affect vapor flow. It would just sit quietly until the pressure exceeded the set point, then the safety would just lift to release the pressure ... and unfortunately the potentially explosive vapor as well ... but that's another story. It's just a small version of the kind you might find on a marine propulsion boiler or something like that.

--JB"
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Offline DGdistill  
#12 Posted : Thursday, June 14, 2012 5:33:52 AM(UTC)
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"Essentially what he said. The pressure relief valve would never operate under normal situations. Only used in emergencies (clogged column, inattentive operator, etc.). I've seen imploded and exploded stills (not mine), and thought there must be an easy fix for this. I know they are common on industrial fermenters, and boilers and not that expensive.

Explosive vapor is an interesting point. I'll have to think about the abv of the pre-column vapor from a typical mash. Maybe not an issue for a first run, but if you are double distilling, you definitely want that valve exhausting very distantly from any heat source. . . ."
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