Sauron
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PTFE Raschig Rings at Affordable Prices
I recently reported here on a commercial source for ceramic burl saddles in 6mm at a relatively low cost, about $100 for 1250 pcs (c.1 liter volume).
Do the sums, that is about 8 cents per piece.
6mm is too large for small colums.
So I obtained quotes from a local PTFE tubing manufacturer for a variety of sizes from 3 mm to 6 mm OD all with 0.5 mm wall and cut to same length as
OD. I asked for qty 5000 each.
I was quoted between 4 and 6 US cents per piece.
This includes the material.
So if anyone wants some of this at my cost, please let me know.
3 mm OD x 3 mm long, 2 mm ID
4 mm OD x 4 mm long, 3 mm ID
5 mm OD x 5 mm long, 4 mm ID
6 mm OD x 6 mm long, 5 mm ID
This tubing is extruded from Dupont PTFE resin. They also make 1mm wall which is even stiffer.
I will sell this by volume and will only have a good estimate of pcs per L or pcs per 200 ml, after measuring actual product However that will not
affect the unit cost (per piece) which will remain in the 4 to 6 US cents range.
[Edited on 20-6-2008 by Sauron]
Sic gorgeamus a los subjectatus nunc.
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-jeffB
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Forgive me if this is trivial or obvious, but how much difference does wettability of the rings make? Should PTFE rings perform better or worse than
ceramic or glass, where the vapor/liquid in question "sticks" better to one than the other?
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Phosphor-ing
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@Sauron which size would be the best for a 19/22 jointed column? I would be interested in enough of that size to fill a 30cm column.
"The nine most terrifying words in the English language are: 'I'm from the government and I'm here to help.'" -Ronald Reagan
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Magpie
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I also have a 19/22 column but it would have a working length of only about 18cm. I've calculated 32ml of rings would fill it. So I'm thinking I
should get 100mL while I'm at it.
The column ID appears to be ~15mm. What size ring would you recommend for that ID?
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Sauron
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For such small columns I think the 3mm rings make sense.
Those are 3mm OD, 3mm long and 2mm ID. '
These are about 4 cents each, compared to 10 cents from Chemglass and 40 cents from Aldrich.
I will pack them same as Chemglass, in 200 ml and 1 liter volumes. When I have a better idea of what that means in terms of number of pieces for any
given size I will post here.
Glass raschiga this small are not available and neither are ceramic saddles AFAIK.
Sic gorgeamus a los subjectatus nunc.
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MagicJigPipe
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This sounds like a pretty good deal and I would love to have some for my 24/40 300mm column, but what about international shipping costs? Wouldn't
that be at least $20?
"There must be no barriers to freedom of inquiry ... There is no place for dogma in science. The scientist is free, and must be free to ask any
question, to doubt any assertion, to seek for any evidence, to correct any errors. ... We know that the only way to avoid error is to detect it and
that the only way to detect it is to be free to inquire. And we know that as long as men are free to ask what they must, free to say what they think,
free to think what they will, freedom can never be lost, and science can never regress." -J. Robert Oppenheimer
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Sauron
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Nah. These things are very light and I have friends travelling to the US all the time who can bring them in and mail them on domestically.
Not a big deal. They are essentially little plastic beads. Declared that way, it's a snore.
Sic gorgeamus a los subjectatus nunc.
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