Sciencemadness Discussion Board

Best tubing for chemistry

plante1999 - 18-7-2013 at 05:23

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!

bfesser - 18-7-2013 at 05:48

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.

chemcam - 18-7-2013 at 07:32

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.

Dr.Bob - 18-7-2013 at 07:33

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]

Magpie - 18-7-2013 at 07:34

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.

chemcam - 18-7-2013 at 07:37

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]

bfesser - 18-7-2013 at 07:38

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&mdash;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]

Dr.Bob - 18-7-2013 at 09:03

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.


annaandherdad - 18-7-2013 at 09:24

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?

watson.fawkes - 18-7-2013 at 16:43

Quote: Originally posted by Magpie  
I suspect that most black O-rings are made of Viton, even those purchased at a hardware store.
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.

Magpie - 18-7-2013 at 18:17

Quote: Originally posted by watson.fawkes  
Quote: Originally posted by Magpie  
I suspect that most black O-rings are made of Viton, even those purchased at a hardware store.
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]

Funkerman23 - 18-7-2013 at 20:00

Quote: Originally posted by annaandherdad  
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?
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]

subsecret - 18-7-2013 at 21:22

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.

AndersHoveland - 18-7-2013 at 21:30

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.

CaliusOptimus - 18-7-2013 at 23:54

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.

bfesser - 19-7-2013 at 05:52

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.

Antiswat - 19-7-2013 at 05:57

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

plante1999 - 28-8-2013 at 06:16

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.

Bezaleel - 28-8-2013 at 09:39

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.