Sciencemadness Discussion Board - First glassblowing project - sealed multi container gas bubbler/absorber with PTFE or glass connection joints

First glassblowing project - sealed multi container gas bubbler/absorber with PTFE or glass connection joints

RogueRose - 24-7-2018 at 19:21

So I've found that bubbling gasses into water in a tall graduated cylinder works best b/c the bubbles have further to travel upwards. A 250ml cylinder (holds 300ml to over-flow) is about 31cm but about 26cm to the 250ml mark - the cylinder is just under 40mm diam with 1.62mm thick walls - making it nice for heat transfer.

I plan on making 3 cylinders of the same size but the walls are 2.2mm unfortunately (can't find thinner). At the top of the cylinder I'm going to draw in the sides so that a female 24/40 or 24/29 joint will fit.

The 24/40 or 24/29 male connector will have 2 8mm OD tubes running down through it, the top of the male joint will be sealed around the the tubes and the outer edge of the connector - air-tight. One tube will only run down about 1" into the male joint, which will allow gasses to flow out of the cylinder and the tube will run 2-6" up from where the male connector is sealed.

The bubbler will run to 1.2" from the bottom of the cylinder (about 28cm where a fritted glass bubbler will be attached that will be .2" from the bottom of the cylinder). These fritted bubblers can pass air with about 2-3 PSI and make extremely small bubbles over the entire surface including the bottom. The tube will extend 2-6" above the joint seal as well - both of these are for later bending to desired angles/directions.

That will be one unit that is sealed with a removeable male plug which houses the air bubbler and exhaust pipe.

I'll make 2 others like this so they can be daisy chained. I am trying to figure out the best way to connect each unit to the other and have 2 options that I can see. One is to get PTFE rod (say 12mm diam) and drill an 8mm hole through it. These could be used to link the exhaust from one absorber to the input of the next one.

The other option is to use very small ground glass joints, like those used in marijuana smoking pipes. Here are the different small sizes that are available. Since the first # is the outer diameter of the male (or inner diameter of the female) and I'm working with 8mmOD tubing (which I could switch to 10mm OD w/ 1mm walls, which might be better IMO - I went of a Chemglass bubbler tube size) then the 7 series would probably be adequate for either of them. I'm thiking a
7/10 joint would work best. This may be much more expensive than the PTFE rod & drilling (that would be $5 or so).

Small Joint sizes available:
7/25
7/16
7/15
7/10

10/30
10/19
10/18
10/10
10/7

12/30
12/21
12/18
12/10

The extra length above the male plug is so they can be bent or so a joint like above can be added.

One issue is getting the gas from a flask or condensor to the bubbler. if coming off a condensor (male end), I could get a female joint and run the 8mm or 10mm tube from that which would then feed the first bubbler/absorber. but here again I would need to use one of those 7/10 joints or a PTFE coupler.

Since my plan for this isn't ccertain yet, I know I will be trying to make things like Oleum, fuming nitric (red or white), pure HCl, high purity ammonia, SO2, NO2 and probably many others, SO IDK if a PTFE connector is going to hold up to this abuse from the chems, but I am also not sure if I can find 7/10 connections.

This is going to be my first glassworking project along with making a large spiral "condensor" or heat exchanger (maybe both) - well actually just a long coil of 8 or 10mm glass, possibly inside a PVC pipe.

If you can follow what I wrote above and have any suggestions on the PTFE vs 7/10 joints and how the chemicals may effect the former, I'd love to hear your input and also suggestions for any other glass blowing projects.

PS, I saw a shop that sell custom science glass that had a serial scrubber/bubbler and they used ball & socket joints b/c they had to be able to twist and turn them to fit in odd locations like a small fume hood.

*final note - each cylinder will have some kind of stand like a PVC pipe in which the very bottom sits to keep it stable - it will also have a lead weight epoxied in the PVC to keep it sunk and stable when it is submerged in ice cold water.

[Edited on 7-25-2018 by RogueRose]

Chemetix - 24-7-2018 at 21:19

Without a diagram I can assume you want to make a Dreschel bottle of some sorts....there are some tricks to this glass project.

Firstly what glass blowing tools experience do you have? There are a few good glass blowing forums and channels getting around. Beginners can rely on Torch Talk and their many web demonstrations ( mainly artistic techniques) otherwise there are some youtube vids around, Kevin Teaford has a few good ones often with lathework but the fundamentals with scientific joins are instructional.

Going through the basics of glass blowing is going to take some time, and more than one or two posts. If you need some more pointers as you make an attempt HMU with questions.

Sulaiman - 24-7-2018 at 23:29

Last year after some glass tube bending I considered having a go at lampworking,
then I reminded myself how many hobbies I already have and how easily I get side-tracked
(e.g. this chemistry hobby started just because I wanted to tin-plate some electronics)

There is quite a start-up cost for lampworking, also lots of skill, experience and techniques are employed,
(I am mesmerised by YouTube scientific glass blowing videos)
so unless you think that this will provide an income,
or be your main hobby,
I suggest that you just buy common glassware and improvise a little.
or get an experienced lampworker to make stuff for you.

---------------------------------------------------------------------------------
I too noticed that the deeper the wash/scrub/absorbtion liquid the better,
and more significantly, the smaller the bubbles the better,
unfortunately both approaches increase the pressure in the experiment glassware
- e.g. pushing ground joints apart causing gas leaks, addition funnels MUST be pressure-equalising types etc..

Rapid stirring also seems beneficial but I'm not sure as I've not done real tests.

Other than potential suckback,
the biggest problem that I have had with bubblers is blockage
which is scary because I imagine explosive pressure buildup and panic a little.
It seems that if there is any possibility of precipitate, it will form a blockage.
Blockages have happened to me more than once so it is something that I should plan for - next time

Also, if gas production is not fully under control, bubbling/foaming can carry liquid over to the next stage.

So, that was a quick summary of some of ways that I have found to make mistakes

------------------------------------------------------
For gasses that are not too active on plastics;
a cheap high-flow bubbler can be made from pvc tubing, a PET drinks bottle (optionally some glass tubing) and one of these;
https://www.ebay.co.uk/itm/2x-Aquarium-Bottle-Cap-for-DIY-Li...

[Edited on 25-7-2018 by Sulaiman]

RogueRose - 25-7-2018 at 10:57

Quote: Originally posted by Chemetix

Without a diagram I can assume you want to make a Dreschel bottle of some sorts....there are some tricks to this glass project.

Firstly what glass blowing tools experience do you have? There are a few good glass blowing forums and channels getting around. Beginners can rely on Torch Talk and their many web demonstrations ( mainly artistic techniques) otherwise there are some youtube vids around, Kevin Teaford has a few good ones often with lathework but the fundamentals with scientific joins are instructional.

Going through the basics of glass blowing is going to take some time, and more than one or two posts. If you need some more pointers as you make an attempt HMU with questions.

Thanks for putting a name to the equipment! that is basically what I had in mind, my idea differed slightly though but functionality is basically the same.

Here is an auction lot I found that shows basically what I want to build:
https://www.ebay.com/itm/Drechsel-gas-washing-bottles-complete-100ml-9-bottles/263734224942?hash=item3d67c8e82e%3Ag%3AUYIAAOSw3uFbE-~d&_sacat=0&am p;_nkw=Drechsel+bottle&_from=R40&rt=nc&_trksid=m570.l1313

As far as experience, I have little, except for a few hours working with a professional glass blower. I'm hoping to work with him while making these and using his guidance and help to complete the project. He's pretty skilled so I think these should be achievable. It seems like a pretty straight forward process with what I have in mind.

These are what is being sold in the link. Basically the same idea, but I wasn't envisioning the dome above the male joint, I thought more of a solid, flat glass area which held the 2 glass tubes in place. I can see the benefits of this, especially if there is bubbling/foam. Will have to ponder.

[Edited on 7-25-2018 by RogueRose]

RogueRose - 25-7-2018 at 11:17

Quote: Originally posted by Sulaiman

Last year after some glass tube bending I considered having a go at lampworking,
then I reminded myself how many hobbies I already have and how easily I get side-tracked
(e.g. this chemistry hobby started just because I wanted to tin-plate some electronics)

There is quite a start-up cost for lampworking, also lots of skill, experience and techniques are employed,
(I am mesmerised by YouTube scientific glass blowing videos)
so unless you think that this will provide an income,
or be your main hobby,
I suggest that you just buy common glassware and improvise a little.
or get an experienced lampworker to make stuff for you.

---------------------------------------------------------------------------------
I too noticed that the deeper the wash/scrub/absorbtion liquid the better,
and more significantly, the smaller the bubbles the better,
unfortunately both approaches increase the pressure in the experiment glassware
- e.g. pushing ground joints apart causing gas leaks, addition funnels MUST be pressure-equalising types etc..

Rapid stirring also seems beneficial but I'm not sure as I've not done real tests.

Other than potential suckback,
the biggest problem that I have had with bubblers is blockage
which is scary because I imagine explosive pressure buildup and panic a little.
It seems that if there is any possibility of precipitate, it will form a blockage.
Blockages have happened to me more than once so it is something that I should plan for - next time

Also, if gas production is not fully under control, bubbling/foaming can carry liquid over to the next stage.

So, that was a quick summary of some of ways that I have found to make mistakes

Great info here! I too worry about blockage and back pressure/explosions when doing this, and have learned how to work with setups which greatly limit this and most reactions don't produce much foam (unless under vacuum) and only gases - at least the ones I'm planning.

As far as equipment, I befriended a local glass blower a little while ago and am going to be taking some lessons and he has offered the use of his shop (while he is there working as well) so I plan on doing my glass work there and not invest in equipment.

When it comes the the construction of the bubblers, I too found that the taller (deeper soultion) the better and small bubbles are a MUST. I have one bubbler I am basing my design off of and it creates "micro bubbles" by using an extremely fine glass frit for the "air stone" part.

The tube in the picture is 8mm OD and the bubbler is about 1/2" OD x 1" long and there is almost no restriction when blowing through it (a similar size air stone required about 5-8x the pressure to pass through and created much larger bubbles - possibly due to higher pressure) a very light blowing of air through lips passes easily through the entire surface area of the bubbler. This should greatly reduce the needed pressure to make this work.

Now you have me thinking about the possibility of adding a small magnetic stirrer on the bottom (36mm ID so maybe 10-20mm length??) of at least the first bubbler. The swirling of the mini bubbles should help keep them in the water longer, have much more contact time with with the liquid. I figure the pressure build up in the cylinder (causing the male joint to want to pop off) can be fixed with either metal clips or with proper application of copper or stainless steel wire.

I made one of those lids/caps you posted out of a media reagent bottle and a GL45 lid, placed some silicone gaskets in the holes and put the glass tube down through them. It worked OK but they aren't as tall as a grad cylinder.

Now if stirring greatly increases the retention time of the bubbles, then it just might be possible to use one of these reagent bottle setups instead, with stirring obviously. I'll have to test how long the bubbles remain in the liquid while being stirred once I get some stir bars.

Here is a picture of the bubbler that I have and the glass frit bubbler end. It is supposed to screw onto some kind of media bottle (unique to the manufacturer it seems) and this is meant to oxygenate liquids to keep organs alive (so says the web site at least).

This project is more for learning how to do some things with glass (bending, using frit, customizing ground joint ends, sealing open ended tubing to be flat, tapering the tube - to receive the female joint, etc) Seems like a bunch of good skills that could transfer to other projects, and I need something like this, so thought it would be a good start.

[Edited on 7-25-2018 by RogueRose]

Sulaiman - 25-7-2018 at 14:17

Quote: Originally posted by RogueRose

As far as equipment, I befriended a local glass blower a little while ago and am going to be taking some lessons and he has offered the use of his shop (while he is there working as well) so I plan on doing my glass work there and not invest in equipment.

Lucky

I am jealous

Making a wash bottle is useful, but I often see bargains on eBay.
Two pieces of glassware that I would like are
. Perkin triangle, available but pricey
. Variable take off still head adapter, rarely available and very expensive
but those are my dreams.
Maybe a vacuum-jacketed column, preferably silvered,
or a super efficient condenser ?

wg48temp - 25-7-2018 at 14:41

Quote: Originally posted by RogueRose

That’s a great start. He presumably will have all the torches, equipment and skills you can use and learn.

I spent a lot of time struggling with soda glass and map torch. Usually as the part cooled down it would crack. Borosilicate glass was much more forgiving but you needed propane /oxygen torch to do anything other that bend a glass tube. I have watched a scientific glass blower and neon sign fabricator they make it look very easy but that’s true of most of those types of hand eye skills. Of cause we now have YouTube.

[Edited on 25-7-2018 by wg48temp]

RogueRose - 25-7-2018 at 15:52

Quote: Originally posted by Sulaiman

Quote: Originally posted by RogueRose

Lucky

I am jealous

Could you explain the vacuum jacketed column? you aren't talking about a cromotography column are you..? A column, possibly vigerux inside a vacuum jacket? and possibly have the jacket mirrored to direct heat back into the vigurex (or whatever) column? That may not be super hard for my friend. I've worked some with mirroring with copper and only a tiny bit of silver ( need to make some pure silver nitrate sometime).

As far as super efficient condenser, I'm interested in the same. What kind of condenser are you looking for. I've considered a liebig that has a center water column running down the center.
So say it is 45mm diameter outer jacket, then a 32mm diam inner tube - that would be a standard liebig. But then you would put a 20-24mm diameter tube in the center (water flows in the center of this as well, out into the outer jacket) so the gas flow would have cooling from the outer jacket and the inner tube and have 4-6mm clearance around the inner 20-24mm diameter center cooling tube. This would give a lot more surface area. The only way I could think to improve upon this would be to also have a spiral wrapped around the central tube - in the 4-6mm flow area (not a tight spiral, enough space between each turn to fit another piece of the spiraled tubing - the spiral could be cooled as well). Then gas flowing through would have 3 cooling surfaces - outer jacket, inner core and spaced spiral. The gas would flow up and around the condenser being directed by the spiraled glass.

I would think you could get away with a pretty short condenser if made this way, but IDK why you couldn't just use a larger one.

What suggestions do you have? I'm getting ready to order glass to work with and will order stuff that I can use to learn some things which can later be applied.

Sulaiman - 25-7-2018 at 22:34

The suggested jacketed column is for fractional distillation,
the simplest type being a Hempel column, packed with Raschig rings, glass spheres, wire wool etc.
The vacuum and silvering work exactly like in a 'Thermos' flask,
except a vertical stripe is left un-silvered for viewing internal operation.
Just google "vacuum jacketed column" for info.
The difficult part would be the bellows section that accommodates differential thermal expansion between the inner and outer walls.

For the condenser - I don't know

I imagine an outer jacket and a spiral inner carrying the cooling water,
almost as per your description,
but using three plain tubes may be a simpler start.

Have fun
I'm still jealous :cool:

andy1988 - 26-7-2018 at 00:42

Quote: Originally posted by RogueRose

I too am jealous.

Disclaimer: I am no expert! I am just an amateur I apologize if I make inaccurate claims below.

Along with Sulaiman I am also interested in reflux column heads, and custom fractionation columns (where feed plate location, column diameter, number of plates, plate distance, etc are specified). Personally I wouldn't care for a vacuum jacketed column or silvering it, I'd argue that less useful than a properly designed column for the distillation at hand. One can then make their own temperature controlling jacket depending on need using:

a wrapping of aluminum foil
whatever insulation they have laying around
active heating coil sections and temperature control of them (see NIST document below)
pvc pipe with gas evacuation port (silicone o-rings around inner column) filled with: fumed silica, other insulation, or void. This is what flame proof vacuum insulation panels are (packed fumed silica), I think this a superior use of resources/$ over glass silvered vacuum jackets, unless silicone/pvc melting point exceeded in column
separately designed glass jacket (possibly silvered) (see NIST document below)

I've been thinking about setting up a group buy with other people for some large glass fractionation columns from India. One supplier's product appear to be very inexpensive... cheaper than Chinese goods on aliexpress and ebay. Really funny to often see a U.S./European company product/brand they market on their website, and you also see that product sold by the actual manufacturer on alibaba/aliexpress (without branding), often for significantly less $.

Quote: Originally posted by RogueRose

As far as super efficient condenser, I'm interested in the same. What kind of condenser are you looking for.

Specifically I'm looking to design an oldershaw column, or bubble cap column, which would then be blown by a scientific glassblower. Look at this oldershaw column.
The mass produced vigreux columns are not sufficient for my needs of separating the similar bp comonents of turpentine (a tower of vigreux plates would be impossibly high).

My nearby uni does occasionally sell no-longer-needed large oldershaw columns and bubble cap columns for cheap ($15-$25!), but something custom designed would be very useful.

Quote: Originally posted by RogueRose

What suggestions do you have? I'm getting ready to order glass to work with and will order stuff that I can use to learn some things which can later be applied.

Read this NIST document (also attached). It contains glassblower specifications for a bubble cap column (I'm not sure what the proper modern nomenclature for it would be), separate column jacket, reflux regulator (reflux column head) of both variable reflux ratio type and constant reflux ratio type. It also details transport of the glassware and the read is quite short and concise. Some more glassware in there. Though it is quite old I found it very informative. Note as it details, the large columns are built & joined section by section (tray by tray)... I'm not sure with what tools you'd do this as a glassblower. I guess it is different then your first glassblowing project and more about fractionating columns though.

There are a couple scientific glass books in the SM library.

Share photos of your completed work with us!

Attachment: jresv7n5p851_A2b.pdf (2.9MB)
This file has been downloaded 390 times

[Edited on 26-7-2018 by andy1988]

Sulaiman - 26-7-2018 at 03:00

Quote: Originally posted by andy1988

Specifically I'm looking to design an oldershaw column, or bubble cap column, which would then be blown by a scientific glassblower. Look at this oldershaw column.

Due to illness my progress is slow at the moment but I have been experimenting with ethanol fractional distillation
(cheap feedstock)
and I also want to distill kerosene/paraffin,
I was given c25 litres of 'old' paraffin that burns with quite a bit of soot that I would like to make usable,
and see what fractions are there.
I'm still toying with the idea of continuous disillation;
pre-heat feedstock, rectification and stripping sections etc.
I've not even got my batch distillation rig working properly yet,
so I'm not going to start a continuous system or I'll never have a fully working rig.

I fancy an Oldershaw just for the reported sound :cool:

but I doubt that it would have more plates-per-vertical-height (lower Height Equivalent to the Theoretical Plate)
or throughput, than a Hempel/packed column.
but it should have lower holdup,
which so far has not been a problem for me
- but I've not really tried to isolate very low percentage fractions yet.
My main 'yardstick' is how little 'product' is produced between 'pure' fractions.

My Hempel column (2x 300mm air condensers) has good (but not excellent) insulation
(Paroc rock wool pipe insulation, 25mm thick with alluminised outer, c10W with insulation, c40W without)
even so I am considering external electrical heating.
(or maybe a pipe to convect heat from the heating mantle up around the column)
A silvered vacuum-jacketed column would eliminate such a lot of messy/complicated stuff.
... but I've started, so I'll continue, until I change my mind
(or get this one repaired)

P.S. I could not access that NIST document, could you post a copy please ?
and
a Hempel column is easy to clean
and
I wish I had built into my rig at least one spherical joint,
with just a pot, simple column, condenser etc. I had various common problems,
but with many pieces of ground joint glassware interconnected clamping becomes problematic - literally stressful !

@RogueRose :
maybe a simple bubbler is a good choice for a first project

Consider possible use in RBFs etc when deciding the length and diameter of the bubbler stem/straw/tube/diffuser ?

ONE MORE !
Maybe a heated (preferably cleanable) vacuum filter funnel which could also be configured to be a cold trap ?

[Edited on 27-7-2018 by Sulaiman]

andy1988 - 26-7-2018 at 12:07

Quote: Originally posted by Sulaiman

P.S. I could not access that NIST document, could you post a copy please ?

Ok I attached it to the referencing post. It is old, from 1931 and they use asbestos everywhere