Sciencemadness Discussion Board - Stirrer Shaft to fit 24/40 and is Acid Resistant

Stirrer Shaft to fit 24/40 and is Acid Resistant

malford - 23-9-2013 at 21:08

I am trying to find a shaft and propeller for an overhead stirrer that can fit through a 24/40 neck and is resistant to all strong acids. Winner will be rewarded with a cookie.

[Edited on 24-9-2013 by malford]

Rosco Bodine - 23-9-2013 at 22:12

http://www.ebay.com/itm/24-PTFE-Standard-Stopper-Teflon-Stir...

http://www.ebay.com/itm/PTFE-Stirrer-300mm-Diameter-7mm-Padd...

Dr.Bob - 24-9-2013 at 07:53

I have glass stirrer shafts, 24/40 holders and a few teflon blades. Can you tell me about how long a shaft and what size flask, and I can see what I have for that. There is a real limit on how big a blade will fit through a 24/40 joint, so that is the main issue. If you have a larger enter joint, then you can really use a big stirrer blade.

Bob

malford - 25-9-2013 at 13:40

Rosco, my trouble was finding a shaft and propeller that could fit through a 24/40 neck in a round bottom flask (i.e. no access to other side as in a vessel/lid) and that is impervious to strong acids (i.e. made of PTFE or PP.)

Dr. Bob, that limit of which you speak is my problem. I can't really find any propeller that will fit through a 24/40 neck that is made of PTFE. It is for a 2L RBF.

Magpie - 25-9-2013 at 18:16

see: http://www.ebay.com/itm/Electric-overhead-stirrer-mixer-shaf...

These are folding prop types.

Also search "ptfe stirrer shaft" on eBay.

[Edited on 26-9-2013 by Magpie]

[Edited on 26-9-2013 by Magpie]

[Edited on 26-9-2013 by Magpie]

malford - 25-9-2013 at 18:37

If that stirrer is fully folded in the image, it wouldn't fit through a 24/40 neck. Have you worked with one of these types before? Does it collapse further?

Also, just FYI. I have searched for hours using every combination of search terms on eBay, Google, and all major manufacturer websites. So far I have not been able to find a PTFE stirrer that looks likes it will fit through a 24/40 neck.

[Edited on 26-9-2013 by malford]

BromicAcid - 25-9-2013 at 18:51

10 mm glass stir shaft with button:

http://r.ebay.com/D5yKQ6

Then buy a separate stirrer blade for that shaft:

http://r.ebay.com/7sAyjA

So long as the blade fits the shaft you can easily trim down the blade with a pair of scissors to make it the right size to fit into the neck of your flask.

malford - 25-9-2013 at 18:56

You, sir, solved my problem!

Dr.Bob - 25-9-2013 at 19:40

Here is a photo of some stirrer shafts and adapters. I have some more pieces elsewhere as well, but have to find them still. The bottom link is a photo of some of the 24/40 bearings in better resolution. I also have a few other sizes as well.

https://docs.google.com/file/d/0B80lrYgm1HCvS3kwQlZnZUliMUk/...

[Edited on 27-9-2013 by Dr.Bob]

Magpie - 25-9-2013 at 21:03

This one specifically says it will fit a 24/40 neck:

http://www.ebay.com/itm/PTFE-stirrer-90mm-blade-10mm-550mm-s...

For those that don't specifically say I suggest you submit a question to the seller.

malford - 26-9-2013 at 05:22

Thank you, Magpie!

Bob, do you know if any of those bearings will work under vacuum?

Organikum - 27-9-2013 at 03:07

They should be all precision grounded and with the stirshaft also precision grounded and some grease they are perfect for vacuum.
Speed is limited though, higher speed would callfor watercooled bearings.

It is just that the grounded part of the shaft (mostly only a part is treated this way) is in the right position for the bearing.

But I am sure DrBob can and will provide you with a set fitting for your 2l RBF.

Dr.Bob - 27-9-2013 at 05:19

As Organikum says, they can work with vacuum if greased properly, but I would say that they will only work under a mild vacuum well. Any moving joint will leak a fair amount of vacuum at a good stirring speed, so you will not be able to keep a real high vacuum. Most stirrer like this are used for reaction stirring, under a slight inert pressure, which helps to keep the grease or oil from leaking in to the flask to a significant extent. I also do have a couple of water cooled bearings somewhere, if people think that they will be needing them. I am still trying to collect all of these pieces, they were scattered among several boxes, and I will try to get better photos with time.

PS. Can someone tell me how to link a larger photo in a thread via a URL? I have some better photos, but this forums silly photo sizes are killing me. In some forums, you can simply use [IMG] url [/IMG] to insert a real photo, but I could not make it work here.

malford - 27-9-2013 at 06:45

I use imgur.com to host photos. Thanks for your time, Bob.

Magpie - 27-9-2013 at 10:39

I have a ptfe folding prop type stirrer and bearing for size 19/22. I have used it several times but I don't recall ever using it under vacuum.

Embedding Images with BBCode

bfesser - 27-9-2013 at 12:10

Quote: Originally posted by Dr.Bob

PS. Can someone tell me how to link a larger photo in a thread via a URL? I have some better photos, but this forums silly photo sizes are killing me. In some forums, you can simply use [IMG] url [/IMG] to insert a real photo, but I could not make it work here.

The BBCode works fine, but you can't have any spaces between the <a href="faq.php?page=messages#7">BBCode tags</a> and the URL.

Code:

[img]URL_here[/img]

Make sure that "Turn BBCode off?" is unchecked before posting. The BBCode tages aren't case sensitive, but be consistent and use either all caps or all lowercase for your tags. Also, beware that I will edit posts to reduce the display sizes of larger images (usually those greater than 800 px in width) as necessary. If you'd like, you can embed thumbnails which link to full-resolution images on an external host.

Code:

[url=full_resolution_URL_here][img]thumbnail_URL_here[/img][/url]

Finally, you could use HTML—as I regularly do—to insert images or format your posts. It's much more flexible and—I think—straightforward.

Code:

<img src="URL_here" />

<a href="full_resolution_URL" target="_blank"><img src="thumbnail_URL" /></a>

One last thing to mention: If you copy-paste the horrible code from imgur.com or any other annoying image hosting service, don't be surprised when I edit your posts.

[Edited on 27.9.13 by bfesser]