plante1999
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Best tubing for chemistry
Very Often, in chemistry, tubing are used. they can ether be used in conjuncture with glass tubing and rubber spotter, or for vacuum and ground glass
work. Here is what I found, and yet after all these tests, no tubing was suitable for my chemistry uses.
Glass
Glass can be got from chemical material supplier in the form of lime glass tubing, it is quite expensive. Most hobby supplier will only have two size
which very often won't be the same as another supplier. Glass need to be worked with flame to be designed. Glass break easily, is not flexible or
elastic, but it will withstand most gas an home chemist could make. I recommend it, but its price and non-flexibility lower the value of the tubing.
Natural rubber (isoprene)
Natural rubber tubing is very costly, about 2-3$ per feet, and can be bought from chemistry equipment supplier. They are very elastic, and very
flexible, however they are fairly easy to destroy by chemical treatment. Mostly everything slightly corrosive will eat the rubber off. Recommended
only for non-corrosive gas, vacuum etc...
PVC
PVC, in the form of flexible tubing can be found very easily (and cheaply) in hardware store as "vinyl" tubing, they are clear and flexible, and very
slightly elastic. Since they are PVC tube, one think they are fairly chemically resistant, but it is generally not the case. I believe it is due to
very high plasticizer content. PVC will withstand soft gas and chemicals, for example sulphur dioxide, however, with strong chemical, it will swell,
decolorise, or harden. Not recommended.
Fuel line rubber
Fuel line rubber can be found on old engines, such as snowmobile or car, they can also be bought from an automobile supplier. The rubber is
polysulphide rubber. This rubber is quite good for non oxidizing gas, it is more elastic than PVC.
Polyethylene
It can be got cheaply from hardware store. It is chemically resistant, non elastic and slightly flexible. I would say it is one of the best tubing
material I tested due to its very long life in a laboratory coupled with its very low price.
Teflon, PTFE
Teflon is completely non-elastic, and slightly flexible. It is very expensive and extremely chemically resistant. I do not recommend it due to its
non-elasticity and the price.
Neoprene
I have yet to test neoprene, and don't even know if neoprene tubing are available, however, if some are available, they should be elastic, very
flexible and somewhat chemically resistant.
Viton
I have yet to test Viton tubing, which is made from fluoroelastomer, it can be bought from the net for a costly, but probably well invested price.
Since it is similar to teflon in chemical composition, it is believed to be highly chemically resistant. It is flexible, and more elastic than PVC.
Other rubber
Some other rubber, without double bond in them could be very good potential rubber for home chemistry, example is butyl rubber. It wort investigating
if one can find such rubber tubing.
Hopefully it was helpful, if someone have tested something not in the list, please report it!
I never asked for this.
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bfesser
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Or you could check one of the hundreds of published material compatibility charts…
Something which you could add; the best places to source each type of tubing.
For example, I've found that Carolina Bio. Supply Co. has the elusive <a
href="http://www.carolina.com/lab-tubes-tubing/red-vacuum-and-pressure-tubing/FAM_711558.pr?catId=&mCat=&sCat=&ssCat=&question=vacuum+
tubing" target="_blank">red rubber vacuum tubing</a> <img src="../scipics/_ext.png" />.
Anyway, thanks for the refresher, <strong>plante1999</strong>. I'm sure many newcomers will find this quite helpful.
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chemcam
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Don't forget about Tygon 2375 it claims to be "Plasticizer Free Ultra Chemical Resistant Tubing" I think the composition is a proprietary blend but I know the brand
name "tygon" is used quite often in the USA.
Don't forget there are hundreds of types of tygon tubing so you need the number that follows as well when researching.
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Dr.Bob
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Here are a few comments:
Natural rubber - Often the best for thick walled vacuum tubing - the 1/8" - 1/4" thick walled version, in red or black, most often, will work well for
vacuum line use. This stuff does pretty well for its cost.
PVC - This is what is seen as Tygon brand tubing, (and knockoffs) which is used for most simple purposes in every lab I have been in. Great for
delivering inert gases, mostly in 1/4" ID with a 1/16" wall thickness. Also fine for moving water from a tap to a condenser and to the drain. Thick
walled versions versions can be used for vacuum tubing, but they will outgas plasticizers. These will not work for long with almost any organic
solvent, and I would RARELY use them for any organic liquids.
Fuel line rubber - Most fuel lines I have seen recently are black neoprene or Viton based rubber, which are a chlorinated or flourinated rubber.
These are great for many hydrocarbons, but will not handle all chemicals well. Too soft to handle a vacuum well, unless very thick, they just
collapse.
Polyethylene - i agree than this can be useful for some gases and liquids, but very hard to work with as it is very rigid. Warming slightly can help.
Teflon, PTFE - Only easy to get in 1/8" or smaller diameter. But great stuff for many chemicals. Other fluoropolymers are used for small diameter
somewhat rigid tubing, but they are similar to Teflon as well.
Neoprene - chloronated tubing with similar properties as Viton. I have seen some tubing labelled as Viton, which was likely really more like
neoprene. These will handle many hydrocarbons and other chemicals well, but do not handle DCM, TFA, and other halogenated solvents well for long
times, as they swell it badly, and they also can also soften from some chemicals. But for many purposes, they are good.
There are some great fluoroelastomer tubing, especially those made by the Gore company, but they are pricey. But even those have a variety of
chemical resistantance. The best stuff I have ever seen was slightly elastic and could withstand any chemical I tested, was flexible at -100C, and
would not leak easily even when punctured with a syringe needle. It cost a fortune, but is used in peristaltic pump tubing for special uses. I
have some 1/8" gasket material made of the same. It is the best sealing gasket I have ever seen.
[Edited on 18-7-2013 by Dr.Bob]
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Magpie
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Glass Borosilicate glass tubing and rod can be very reasonably purchased from art glass suppliers, eg, Frantz Art Glass.
Natural Rubber Yes this is expensive (>$1/ft), but very nice for condenser water lines and bunsen burner gas lines. It is
available at Lowes and Home Depot in 10 foot sections.
Viton This is an expensive but very chemically resistant rubber. I suspect that most black O-rings are made of Viton, even those
purchased at a hardware store. I'm guessing that most thermometer adapter rubber is also Viton.
The single most important condition for a successful synthesis is good mixing - Nicodem
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chemcam
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Tygon shouldn't be generalized as only PVC. I have a box from a vendor of about 30 different types of tygon tubing and some of them resist anything I
throw at it. MEK, toluene, acetone and other solvents included.
[Edited on 7-18-2013 by chemcam]
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bfesser
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Personally, I only use soft rubber vacuum tubing (link above) and natural rubber latex tubing to connect to any of my glassware. I'm afraid of stiff
tubing which could potentially break the glass if bumped. I've used silicone, tygon, etc. but only where I absolutely needed the chemical resistance.
Suggestions on how to prevent this have been posted, though (quick disconnects <em>spring</em> to mind). I splurge on the 10' rolls of
latex tubing from Home Depot, as I don't like to take chances with some of my glassware—rotavap condenser.
<strong><a href="viewthread.php?tid=25078">A few unconventional uses for polyethylene tubing</a></strong>
<a href="viewthread.php?tid=13156&page=4#pid240047">[untitled posts]</a>
[edit] Getting some good advice in this thread, so I've added it to my <strong>Topical Compendium</strong>.
[Edited on 7/18/13 by bfesser]
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Dr.Bob
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I forgot about Silicone tubing. It can be pricey as well, but it does very well for certain chemicals. I used to use some of it for my gas tube
connections where there were harsher chemicals, fumes, or solvent vapors, and it mostly did very well. It did not handle DCM and amines for long
times well, but most other chemical vapors it did OK with. VWR even had a good type of no-name silicone tubing that I liked.
For using Teflon tubing, I often do things in ways that worked well with rigid tubing. For example, when transferring a chemical from one flask to
another with 1/8" Teflon tubing, I would use rubebr septa, put a 1/8 hole in each, shove the Teflon tubign barely into each septa, and then dry and
purge my glassware. When the liquids needed to be transferred, I would move the tubing into the bottom of the donor flask flask, put my N2 pressure
into the Tygon or Silicone tubing going into that flask, then put a tube to a bubbler or vacuum (for viscous liquids) source on the recipient flask.
That way there were no joints, valves or other items in the fluid pathway. I have used that trick to transfer strong acids, solvents,
organometallics, and even hydrogen (used a balloon of H2 hooked to a stopcock and Teflon tubing- warning, don't try this at home) before.
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annaandherdad
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I just saw this video, http://www.youtube.com/watch?v=sVJ-WBe9AnE, and it makes me wonder if small sections of porous ptfe tubing could be used as a homemade gas
dispersion tube (which are expensive). Has anyone tried this?
Any other SF Bay chemists?
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watson.fawkes
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If only.
They're mostly neoprene, when I've been able to get a manufacturer disclosure as to the actual material. The one consumer-like place where you
generally see Viton is for gasoline service.
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Magpie
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Quote: Originally posted by watson.fawkes  | | If only.
They're mostly neoprene, when I've been able to get a manufacturer disclosure as to the actual material. The one consumer-like place where you
generally see Viton is for gasoline service. |
I was only surmising it was Viton based on the good performance I've had with Ace hardware O-rings. I've used them to seal a rotating shaft and to
seal a thermometer in nitric acid generation with good results.
But I see from the Grainger site that Buna-N (a nitrile) is a popular O-ring material for the cheaper ones. Who knows what Ace uses. Probably
whatever their tiny parts sub-contractor can get the cheapest at the time.
[Edited on 19-7-2013 by Magpie]
As a side note on my last job we routinely used Viton O-rings for most chemical service. But one application required a 4" diameter Kalrez (a
perfluoroelastomer) O-ring. That ring was unbelievably expensive, >$1000, IIRC.
[Edited on 19-7-2013 by Magpie]
The single most important condition for a successful synthesis is good mixing - Nicodem
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Funkerman23
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Talk about a great idea. I haven't seen
anyone try that bit I'm sure going to now. As soon as I find that kind of PTFE tubing I'm going to anyway.
EDIT: Finding a good source for this stuff is becoming a right PITA. Sure industrial quantities are around but Good lord..this might be difficult.
Still worth it though this would be great for chlorinations and reactions where space is limited.
[Edited on 19-7-2013 by Funkerman23]
" the Modern Chemist is inundated with literature"-Unknown
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subsecret
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Hydrogen chloride will attack some types of tubing. I was producing some hydrogen using a setup consisting of a stoppered filtration flask.
Hydrochloric acid was reacted with aluminum in the flask, and the resulting hydrogen was run out through a PVC (I think) tube. The reaction got going
faster than I was expecting, and the exothermic nature of the reaction released gaseous HCl. Once this hit the PVC tube, it just sagged.
I have found that latex (the orange rubber tubing) is really good for condenser pumps and the like. To slide it onto a hose barb, just wet it a
little. The tubing is really flexible, and I always hang it around my support clamps to keep it out of the way during experiments. Despite its
convenience, latex probably isn't the best for acid vapors or other corrosive gases. I might test this tubing for use with acid vapors, but it serves
well to run inert gases or water.
Fear is what you get when caution wasn't enough.
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AndersHoveland
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Nitrogen dioxide eats up plastic tubing. It can be used, but the inside of the plastic becomes sticky and gunky. Stiff hard plastic seems to be more
resistant than soft flexible plastic. Same problem with rubber stoppers. If you are handling nitrogen dioxide fumes, probably better to buy silicone
stoppers.
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CaliusOptimus
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For all of you who have trouble finding tubing, look no further than mcmaster.com.
I've found 1/4"ID x 7/16"OD Buna-N to be a great choice for vacuum line. It's fairly rigid, but still slides onto glassware easily. The thinner wall
stuff is also my favorite for condenser lines, it stays flexible at 0c but will loose flexibility when working around -20c. Also safe for gasoline,
oils and NaOH @ RT. PVC with a wire support also makes a stout vac line.
If you're a big spender, Viton is an excellent choice for any kind of strong chemicals. I've been using the same Viton thermometer o-ring for 5 or 6
RFNA distillations, just to give an example of it's great chemical resistance.
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bfesser
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| Quote: Originally posted by Awesomeness | Hydrogen chloride will attack some types of tubing.
. . .
Despite its convenience, latex probably isn't the best for acid vapors or other corrosive gases. I might test this tubing for use with acid vapors,
but it serves well to run inert gases or water. |
Natural latex rubber tubing is incompatible with HCl. It
will turn dark brown, stink of H<sub>2</sub>S, and lose the desirable elasticity, eventually becoming brittle and useless. | Quote: Originally posted by bfesser | I can confirm that the sulfur in natural latex rubber tubing will react with HCl (at least in the presence of water), producing
H<sub>2</sub>S, which will contaminate your product. | Quote: Originally posted by bfesser | The apparatus consisted of an all glass HCl gas generator connected to a fritted glass bubbler with a short piece of natural latex rubber tubing.
. . .
The short piece of latex rubber tubing became brown in the middle, where it was exposed to HCl, but remained a light yellow to amber on the ends where
the glass tubing was inserted. The tubing reeks of 'rotten eggs' now. |
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Fantasma4500
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as you can see on this site, PVC is pretty well resistant to chlorine containing chemicals
in order to ruin PTFE you would need pretty well liquid flourine, or something else more flourine rich than PTFE
ive had this confirmed by a polymer educated, so to call it
http://www.vp-scientific.com/Chemical_Resistance_Chart.htm
on PTFE
its very tricky to bend around, heating is not something i like to do, my tubing is 9mm, and i have found that the most effective is actually biting
it, it could be done with tools, that would be alot slower however
for stuff like NO2 / HNO3 i have decided to go with aluminium tubing (6-8mm??)
its relatively easy to bend around, and to get it fitting on a flask you make a hole in a bottle cap (my 250 mL flask fits very very well with a
bottle cap) then hole through bottlecap
the same type of plastic sticks better together than 2 different, ofcourse
so using another bottle cap you smelt it down over the aluminium and bottle cap
it seems very sturdy, cant figure out what plastic bottle caps are mad of really
seemingly its very strong and has high melting point
about PE (HD?) that would be something i would like to get my hands on
98% H2SO4 is stored in HDPE of what i know, so its very chemically resistant and has pretty well balanced properties
also on polymers:
the longer the chains are, the higher temperature they can resist
thats why low density poly ethylene smelts at low temperature, and then goes into high density poly ethylene
very useful to know in pretty well any situation
rubber is not good for high temperature stuff, so anders you surely have something right on that 'idea' (:
PTFE can be found on ebay (i used ebay.de) i bought it in china, meaning free shipping so it wasnt really that pricey
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plante1999
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For a certain project, I just received 10 feet of 1/4 viton tubing. The tubing is very hard, like tire rubber, pretty flexible (enough to be used to
connect glass without clamps). With all the chemical tests I did on it, I was unnable to alter it.
A random, but funny fact, is that the viton tubing was very strongly scented cinnamon. It is believed that the rubber smell bad, and to fix this, they
scented the rubber.
I never asked for this.
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Bezaleel
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I dare to doubt whether that it true, plante1999. I've got some viton tubing as well, and it is scentless. I distilled hydrochloric acid with it,
which did attach rubber stoppers, but left the viton tubing completely undamaged. It neither got porous or degraded in any way I could detect.
The only disadvantage I found is its relative unstretchability (as compared to standard latex lab tubing), which sometimes makes connecting to flask
sprouts etc. difficult.
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