Chemical resistance chart

[mixxer]

Attached lists many common rubbers/plastics and their performance in resisting other chemicals.

Cross referencing this against the lists of chemicals that folk have found when having their likker lab tested shows that virtually nothing is safe to use in a still.

Even teflon only gets a conditional against ethanol. Wonder what the conditions are temperature/concentration/if its vapour??

chem_res-1.pdf

Chemical resistance chart

(1.2 MiB) Downloaded 743 times

[awerdenty]

I dont know how accurate that chart is first off since it says natural rubber, butyl, and epdm are all excellent in ethanol and I have seen people here saying they have witnessed those materials disintegrate in high abv.

Also for the teflon it says its a flourocarbon resin, what that means idk, it may just be ptfe or it could be a differentt form than what we use.

One item thats interesting is UHMW, it seems to have almost all Execellent ratings in categories its rated in, but who knows with if its true based in the rest of the chart

[cob]

Ultra High Molecular Weight (UHMW) Polyethylene is the complete name.

[awerdenty]

Disregard the UHMW, its operating limit is 200F continuous, where teflon is over 500. After looking at several different charts, they all vary wildly in their rating of the same materials under alcohol.

Either way Ill continue to use teflon, especially after the chemist member boiled teflon in like pure ethanol and observed no leaching under a spectrometer(?)

[stilldistillin]

Disregard the UHMW, its operating limit is 200F continuous, where teflon is over 500. After looking at several different charts, they all vary wildly in their rating of the same materials under alcohol.

Either way Ill continue to use teflon, especially after the chemist member boiled teflon in like pure ethanol and observed no leaching under a spectrometer(?)

where is that thread

[InglisHill]

Disregard the UHMW, its operating limit is 200F continuous, where teflon is over 500. After looking at several different charts, they all vary wildly in their rating of the same materials under alcohol.

Either way Ill continue to use teflon, especially after the chemist member boiled teflon in like pure ethanol and observed no leaching under a spectrometer(?)

Yes, because you have only pure ethanol in your still right?

Hold on, why take cuts if that is the case?

[Danespirit]

Disregard the UHMW, its operating limit is 200F continuous, where teflon is over 500. After looking at several different charts, they all vary wildly in their rating of the same materials under alcohol.

Either way Ill continue to use teflon, especially after the chemist member boiled teflon in like pure ethanol and observed no leaching under a spectrometer(?)

Yes, because you have only pure ethanol in your still right?

Hold on, why take cuts if that is the case?

I would also like to know where that thread is. Awerdenty, could you kindly provide us with the link..?
+1 InglisHill.
There are several other components to be aware of in a still.
One of the most agressive would be acetone, that occurs during the foreshots.
Another factor would be the temperature the material is exposed to, in relation to the chemical.
Most chemicals react more violent the higher the temperature is.
From what i have read and with my limited understanding of chemistry, i have found no better alternative for PTFE.
That would be with the exception of flourpaste, unfortunatly it ain't always practical to deal with...but still my favourite sealing agent.

[NZChris]

Thirty odd years ago I got all of the suppliers I was dealing with onto the problem of what could be used for seals with the hot alcohol distillation components that could be expected from my still. There was only one standout answer, and, as far as I am aware, there have been no relevant advances in that technology since then, so the only material I am more comfortable with than Teflon ® is that trusty old flour paste.

[stilldistillin]

Disregard the UHMW, its operating limit is 200F continuous, where teflon is over 500. After looking at several different charts, they all vary wildly in their rating of the same materials under alcohol.

Either way Ill continue to use teflon, especially after the chemist member boiled teflon in like pure ethanol and observed no leaching under a spectrometer(?)

Yes, because you have only pure ethanol in your still right?

Hold on, why take cuts if that is the case?

From what i have read and with my limited understanding of chemistry, i have found no better alternative for PTFE.

And there isn't one. I am an amateur chemist and even PTFE stands up to hot sulphuric acid fumes. We use PTFE tape to seal glass joints when the normal grease will be attacked by chemicals. I've even see it stand up to nitric fumes for a bit. However the only REAL thing that can stand up to nitric acid fumes is butyl rubber gloves. Nitric acid is in a class of its own really.

Our vacuums to hook up to glass distillery kits are coated with PTFE on the inside as well and they are rated to handle almost all chemical fumes. You can imagine chemistry vacuums for distillery kits don't fool around, and many depend on PTFE coatings for years and years of abuse with much more potent and corrosive chemicals and solvents than ethanol or acetone.

In the grand scheme of things, ethanol and acetone are considered much less corrosive than many of the other chemicals that we deal with on an every day basis. For example, we need to get sulphuric acid up to 337c (639f) to even boil and make fumes for distillation. If you get your finger in the way of an alcohol puff of steam, it hurts because of the heat. If you get your finger in the way of a sulphuric acid or nitric acid puff of steam, your finger will set on fire instantly or be extremely burned and possibly lose your finger.

Boiling sulphuric acid will eat a hole through your clothes and skin within seconds.

I know we aren't drinking sulphuric acid, and we are drinking ethanol.. but this should show you what type of awesomeness PTFE actually is. I would stop worrying so much.

I would worry more about this 0.25% or less lead in brass, or the amount of silver solder inside your pipes, than PTFE tape. I'm still not sold.


references:

1. http://www.vp-scientific.com/Chemical_R ... _Chart.htm" onclick="window.open(this.href);return false;" rel="nofollow
2. https://en.wikipedia.org/wiki/Sulfuric_acid" onclick="window.open(this.href);return false;" rel="nofollow

[Maarten1971]

A problem with PTFE might be, that in the unfortunate situation your set-up catches fire, PTFE decomposes into some nasty chemicals:

The health risk from PTFE relates to possible inhalation
of decomposition products. At temperatures in excess of
260°C the polymer will progressively decompose and
give rise to a number of gases including
tetrafluoroethylene (from 430°C), hexafluoropropylene
(440°C) and perfluoroisobutylene (from 475°C). In some
manufacturing operations involving extended exposure
at 400°C, carbonyl fluoride is known to be the main
decomposition product which, in the presence of moist
air is rapidly converted to the highly corrosive hydrogen
fluoride. A complex particulate substance is also known
to be formed from the decomposition of PTFE at
temperatures above 350°C which is thought to be the
cause, inhaled of development of a characteristic
syndrome with influenza-type features (fume fever). The
latter usually manifests itself within a few hours of
exposure but the characteristics usually subside within
48 hours with no after-affects. Some of the products
from higher temperature decompositions of PTFE (e.g.
perfluoroisobutylene) are highly toxic

[der wo]

Here is a chart with hot ethanol vapour. And Ethylacetat and Acetaldehyd:
http://homedistiller.org/forum/viewtopi ... x#p6903604

Here's one very detailed in german language, also mentioning silicone (not safe because of massive problems with Acetaldehyd) and EPDM (not safe because of few problems with Acetaldehyd, only safe for PURE hot ethanol):
http://www.ckd-dichtungstechnik.de/down ... igkeit.pdf" onclick="window.open(this.href);return false;" rel="nofollow

[Danespirit]

Thanks for sharing Der Wo..
I speak and read german, so it was very informative for me.

Maarten1971 well, we won't hope the still catches fire.
If..i think the question about drinking the rest of the product would be void, as one would probably have chemicals from the fireextinguisher in it anyway.

[Brutal]

Well this was a nice read. Let me ask a question here: is the generic, commonly available "white pipe thread tape" as safe as genuine DuPont Teflon? That's always kinda worried me.

[Danespirit]

Yes it is , Brutal.
That would be of course if there is stated PTFE on the roll.
PTFE or polytetrafluoroethylene, is the original formular used by DuPont industries, and patented under the common name " teflon".
The components in the tape are identical with the original formular.

Edit: There are six different colour codes for the tape.

White – used on NPT threads up to 3/8 inch
Yellow – used on NPT threads 1/2 inch to 2 inch, often labeled "gas tape"
Pink – used on NPT threads 1/2 inch to 2 inch
Green – oil-free PTFE used on oxygen lines and some specific medical gasses (a drop of oil in a threaded fitting for oxygen, can cause a explosion).
Gray – contains nickel, anti-seizing, anti-gailling and anti-corrosion, used for stainless pipes
Copper – contains copper granules and is certified as a thread lubricant but not a sealer