Sciencemadness Discussion Board

Glass tubing for leading gasses

sternman318 - 27-6-2011 at 09:16

What is an appropriate size of glass tubing for leading gasses? e.g. generating HCl with NaCl/NaHSO4 or NO2 by ( I have read) heating CuNO3.

Would this suffice? http://unitednuclear.com/index.php?main_page=product_info&am...



[Edited on 27-6-2011 by sternman318]

barley81 - 27-6-2011 at 09:29

Most stoppers have 5mm holes, except #1 and below, which have smaller holes. The vendor will list the hole sizes. Try Elemental Scientific for glass tubing. Though their minimum order is $25, they sell cheap tubing in flint glass and borosilicate and in a variety of sizes. You can punch the holes in the stoppers yourself with their cork borer set (3/16" stopper hole for 5mm tubing). I hope this helped.

sternman318 - 30-6-2011 at 05:49

Thanks for the info Barley. But are these tubes of sufficient size? Will I have to worry about gasses not being able to escape quickly enough and thus a possible explosion? I will be using a 500 mL florence flask

smuv - 30-6-2011 at 06:28

5mm is more than enough, it will not explode. I have used very narrow tubing to generate gasses, never an issue.

Rogeryermaw - 30-6-2011 at 12:07

the part that makes the difference is how fast you mix reactants. this factor will determine the speed at which your gasses are generated. too fast and either your mixture will bubble into the tubes and into your collector ruining your efforts or the stopper will pop out of your gas generator. too slow and you may experience a reduction in pressure which will create a suction. but the glass tubing will more than likely suffice for your needs.

The WiZard is In - 30-6-2011 at 13:13

Quote: Originally posted by barley81  
Most stoppers have 5mm holes, except #1 and below, which have smaller holes.


If la stoppers have 5mm hole this dobe the reason most
people use 7mm tubing.

Remember be careful inserting the tubing, a little lubrication
goes a long way. I still and will forever have two small scars on my
palm [has been ca. 55 years] from right-angle bent-tubing
that broke while I was inserting it into a rubber stopper.

Fisher Scientific years back made a handy rubber device for
inserting glass tubing, I am unable to find it on their web site.
Will have to look for mine and see if it has a name. It's worth
its weight in bandages.

bbartlog - 30-6-2011 at 16:54

7mm? You sure, Wiz? I have all 6mm OD tubing, and even getting the 6mm into a 5mm hole in rubber already requires lubrication (silicone), twisting, pushing and care. I can't imagine getting a 7mm tube into a 5mm hole, nor for that matter needing the extra tightness of fit...

barley81 - 30-6-2011 at 17:02

I have 5mm tubing because it was recommended in The Illustrated Guide to Home Chemistry Experiments by Robert Bruce Thompson. Does 6mm provide a better seal than 5mm, by any chance? I might try it if it does.

The WiZard is In - 1-7-2011 at 09:46

Quote: Originally posted by bbartlog  
7mm? You sure, Wiz? I have all 6mm OD tubing, and even getting the 6mm into a 5mm hole in rubber already requires lubrication (silicone), twisting, pushing and care. I can't imagine getting a 7mm tube into a 5mm hole, nor for that matter needing the extra tightness of fit...


Well - just put la digital calipers on some glass tubing sticking
out of rubber stoppers .... 7.9mm. Granted getting it into the
stopper requires care and good lubrication....! I recommend
glycerin it being water soluble, easy to clean up.

Getting it out .... forgetaboutit.

When I am synthesizing phosphonium perchlorate (ClH4O4P)
[101672-21-3] a leak in the plumbing is not an option!

[Edited on 1-7-2011 by The WiZard is In]

The WiZard is In - 1-7-2011 at 11:57

Quote: Originally posted by bbartlog  
7mm? You sure, Wiz? I have all 6mm OD tubing, and even getting the 6mm into a 5mm hole in rubber already requires lubrication (silicone), twisting, pushing and care. I can't imagine getting a 7mm tube into a 5mm hole, nor for that matter needing the extra tightness of fit...



I believe I have found the source of this .... years ago the
tolerance for flint glass was -1.5mm. Thus you 6mm tube could be
4.5mm, while 7mm tubing could be 5.5mm minimum diameter.

Currently 0.4 (+/- ?) mm for flint (less for Pyrex) is the norm.

By da thermometers are 6.5mm dia. Well my broken
300o C. mercury thermometer is.