Flour Paste and Pressure

[Waygrumpy]

I have been reading these forums for days but am confused about 2 things. Well to be honest confused about a lot of things but that is part of learning. I can find mention of but no real information of the following 2 items.

1. Flour paste. I know there must be a good topic on it but there so many many many references to this procedure I have not found how it works or how I should do it.

2. I have built my still but want to put an over pressure release on it. I built a 2" boka and did drill the hole on the top of the condensor but thought I would replace it with the previously mentioned pressure switch. (I am kind of a nut about safety.) Anyone have any idea of what an over pressure limit might be?

I appreciate any advice of links to this material anyone might have.

[Old MacDonald]

1] Lots of topics, try going thro these... HD Google Search - Flour Paste

I built a 2" boka and did drill the hole on the top of the condensor but thought I would replace it with the previously mentioned pressure switch.

2]Why? Surely a hole in the top will allow any/all pressure to be released. How do you know your pressure valve will work correctly? The hole(s) will also allow you to monitor the effectiveness of your condenser via a mirror and any condensate forming on it.

More searching needed young man!

[Waygrumpy]

2]Why? Surely a hole in the top will allow any/all pressure to be released. How do you know your pressure valve will work correctly? The hole(s) will also allow you to monitor the effectiveness of your condenser via a mirror and any condensate forming on it.

More searching needed young man!

I have been doing my reading i am going bug eyed.

I know that the valve will function because I will buy the same type we use in the semiconductor industry. I intend to still leave a small hole on the top to look at a mirror and examine for condensation to check my condenser. it would appear to me that adding the addition of a pressure release is not only a good idea but I would guess in a commercial environment is an actual requirement.

I intend to purchase the valve from swagelock.com which does ultra high purity parts for medical, semiconductor etc.

As far as the flour paste I assumed the site might have an article on this procedure for newbies to the hobby. Apparently not. Between when I posted and you did I had started googling flour paste.

Thanks for the rapid answer.

[forrestgump]

2. I have built my still but want to put an over pressure release on it. I built a 2" boka and did drill the hole on the top of the condensor but thought I would replace it with the previously mentioned pressure switch. (I am kind of a nut about safety.) Anyone have any idea of what an over pressure limit might be?

Pressure? What pressure? Our stills are all open to the atmosphere and operate at air pressure. It would be a very dangerous hobby if they weren't.

More generally, if you were dealing with a potential pressure situation (and you aren't), surely a hole is safer than a pressure switch? (A hole is much less likely to fail than a pressure switch).

[Waygrumpy]

Oh and you said a hole in the top would release any and all pressure . That kind of depends on how big the hole is. I but a fairly small hole in the top. So i guess I will need to figure out how big it should be as well. I did purposely not solder a couple of the fittings together so I also had a break away point in case of over pressure until I got a pressure release valve in and/or ensured the size of my hole was big enough.

[Ayay]

+1 forestgump! Keep the hole open. The pressure at the top of the column is less than a floating feather. You need to be aware of un-condensed vapours getting past the condenser, and being aware is the first step. The thermometer will give an early warning that the vapours have reached the condenser. You should have turned on the coolant long before the early warning. Secondary warnings are smelling the vapours and observing them, and you really need to be there at this crucial stage.

The danger zone is knowing when to turn the heat down from full-blast to get the boiler up to temp, to a gentle heat for stabilisation and removal of the fore-shots and early heads.

No vapours should get past the condenser. Controlling the coolant flow or the heat level will do it. A pressure valve is a very poor and dangerous last resort because it does nothing more than build up pressure. When it releases it's doing what an open hole would have done in the first place.

And because there is no pressure valve, the pressure will not go beyond a floating feather, and therefore flour paste is a perfectly good sealant.

[Waygrumpy]

Forest there has to be some pressure.

Now I am new and just about to fire up the new toy but it would seem to me that even if there was no top on the condenser the pressure inside the column has to be over atmospheric pressure.

In my case I am boiling liquid (or will be) in a 15.5 gallon barrel. I then restrict about a 16 inch boiler to a 2 inche colum. Taking me from 201 square inches to a bit over 3 square inches. That change in pressure is how we get flow up our column I thought. . Now we do cool it back down at the top at the condenser but it would seem to have to have a positive pressure not sure if it is 1 psi or 5 psi. or whatever but their simply has to be. If there was not we would not worry about steam coming out if there is a leak or crack. It is the difference in pressure between the column and atmosphere that would push that out.

So anyhow it may be an expense you do not want to pay but there is a pressure difference and if the hole in the top of the column were to get pulgged of the point the liquour drains were to plug pressure could build up like a pressure cooker.

I guess I can get a pressure guage from work or put together a small water column to determine what the actual forward pressure is . I just thought someone might know.

Maybe it is just that I am tired and over thinking the subject. I am known to do that.

Thanks again guys for the replies

[Waygrumpy]

Huh ok perhaps I am making a mountain out a mole hill as my Pop used to say.

Tks for the advice guys.

just trying to cover my safety concerns before I fire this toy up .

[astronomical]

A pressure valve is a very poor and dangerous last resort because it does nothing more than build up pressure. When it releases it's doing what an open hole would have done in the first place.

What he said. It's not going to stop vapor from pouring out if it ever blows. The only thing it is going to do is hide the problem (somewhat) until it hits its PSI threshold. I don't even have a cap on my reflux tower. I would also hate to see what would happen if you flooded your tower and 95% ethanol came spraying out at 174F with 5PSI. Now that sounds dangerous!


If you feel the need to use a pressure valve than put it on your boiler. A pot still may have a blocked condenser but all the reflux designs should never build pressure. I remember reading that someone had a plug of ice in their worm. On that note, always make sure your potstill has nothing blocking air flow prior to firing your still.

[Ayay]

See it as the boiler getting hotter and hotter, and slowly the vapours are driven off. The vapours have mass and they like to hug their mother - the boiler. No matter how much they hug their mother, more and more of them are crowding together so they have to go somewhere and the only way is up the column.

So they reluctantly go up the column no matter how much they would rather go down to mother.

Finally after much crowding down below they reach the top of the column and mercy - a condenser - back to liquid they go as hunny to a bee! Really, they will cling to the condenser like a magnet.

But the condenser can only take on so many while remaining cool. Too many and the condenser will loose it's cool, and then the vapours can sneak past and find nirvanna in the open atmosphere.

That's where you come in...

[myles]

Being safety conscious is always a good thing.

It might be slightly inconvenient, but I tend to favour the idea of connecting the air vent on the reflux condenser to its own small liebig condenser. If you do manage to put in too much power to the boiler, or if you get a kinked hose and reduce your coolant flow, it is far easier to see drops of liquid exiting a liebig than it is trying to detect the vapour. The air vent is still open to atmosphere through the libig.

[Husker]

Oh and you said a hole in the top would release any and all pressure . That kind of depends on how big the hole is. I but a fairly small hole in the top. So i guess I will need to figure out how big it should be as well. I did purposely not solder a couple of the fittings together so I also had a break away point in case of over pressure until I got a pressure release valve in and/or ensured the size of my hole was big enough.

Many would recommend a 3/8" to 1/2" hole. If you want a 'vapor escape warning', then place a penny (or other lightweight copper coin) over the hole. Just a loose penny, when you run. If there is any vapor release, the penny will click a little, informing you that there may be a problem.

Many do have any cap AT ALL over the end, and simply have the entire top of the 2" (assuming 2") column open to the atmosphere, which the condenser coil slides down into.


H.

[myles]

It is worth remembering that you don't actually NEED a pressure relief valve. It will only get used if something goes wrong. Same for the vapour escaping out the top of the still - it will only happen if something goes wrong. But it is good insurance.

Getting back to the pressure relief valve on your column, it will only get used if you manage to create a blockage in your vapour path. With this in mind the valve would have to be located on the boiler side of the blockage. On a reflux column chances are that your blockage will be IN THE COLUMN, in this situation a relief valve on the reflux condenser will be no good. You probably want it on the boiler. And you need to make sure that the valve itself can't be blocked by whatever blocked your column.

I am coming round to the idea that the best solution might be a BIG (2" or 3") bursting disc or some sort of water trap, plumbed in to help direct the mixture of boiling wash and vapour to somewhere safe. I just hope no-one ever needs it.

[rad14701]

There should be no pressure buildup in a reflux column just as long as there is adequate venting to atmosphere... If you have inadequate venting then outside air won't be able to adequately enter the still as needed in its ongoing effort to keep the system balanced... That is to say that a properly operating reflux column still will actually draw air in as part of it's operation... If you are a smoker try blowing cigarette smoke towards the open top of a LM or VM reflux column and watch what happens... No, don't try waving a lit cigarette around the top of the still... If the still is functioning properly you should see some smoke get sucked down into the condenser chamber...

Now, that being said, if you don't have your column packed properly you could potentially have a pressure buildup in the boiler... If that happens then either the flour paste would cause a release or an option pressure release would serve the same purpose... But knowing that you can easily breathe through your packed column is a good test and will eliminate the possibility of excessive pressure buildup unless the column floods, and if that happens you'll have a hot ethanol fountain before any relief mechanism could react...

[junkyard dawg]

I almost hesitate to post this, because I don't want anyone to take this the wrong way...

But,

You have to really screw up to create a hot ethanol fountain or need a pressure relief.

I've tried, under controlled conditions, to screw up... just to see how fast you can run your still... To see what happens when you flood the column... I've attempted to get a lot of foam up and block the column packing. What I learned from intentionally running too hard, too hot, too fast, etc...

Your should notice things going haywire before anything crazy happens. If not, you are not paying close enough attention.

Learning how to run the still is a big part of the art of distilling. At this scale, you should be sitting in front of your still and watching everything that happens during a run. Observing column temps and drip rates and the size of the flame under the boiler and the flowrate of the cooling water. Its a constant process of checking and observing and changing jars and tasting and smelling and doing it all over. The still will give you all the info you need about whether its running right of not.

Maybe it is just that I am tired and over thinking the subject. I am known to do that.

I would instead, focus on how to make a good wash or mash. That business is way more problematic than pressure buildup...

[Braz]

Agree with Junkyard Dawg. I can, if I try, flood my LM reflux still. But I can hear it gurgling and getting angry before it starts spouting rocket fuel out the top.

Tend the still. Use all your senses, including hearing.