I'm working up a demo model of a special purpose pump (sorry I can't be
specific about its' function). and need to find some appx 3 inch dia X 1/4W
acryllic tube. The ID needs to be round and smooth enough for a sliding
O-ring seal,similar to a hydraulic cyl. Pressure will be low, about 20 psi.
Does anyone know of any suppliers for a tube that fit the need?

Thanks

--
J Miller

"John Miller" wrote in message
m...
I'm working up a demo model of a special purpose pump (sorry I can't be
specific about its' function). and need to find some appx 3 inch dia X
1/4W acryllic tube. The ID needs to be round and smooth enough for a
sliding O-ring seal,similar to a hydraulic cyl. Pressure will be low,
about 20 psi. Does anyone know of any suppliers for a tube that fit the
need?

Thanks

--
J Miller

Someone may prove me wrong here, but I can't see extruded acrylic tube being
round enough for a good seal. Even small-diameter glass syringe tube is only
round enough for an approximate seal, although it works well when the
elastomeric seal is relatively thick -- as it is in a syringe.

If you can use a thick seal, it's probably no big deal. The tradeoff there
is getting a seal that's soft enough to fill the gap but which will hold 20
psi (probably not difficult, either). But if it has to be an ordinary
O-ring, and if you need consistent resistance from one unit to the next,
I'll bet that you'll have to hone the bore to get that close.

But maybe someone knows of a source of such tubing with precise bore
roundness.

--
Ed Huntress

"John Miller" wrote in message
m...
I'm working up a demo model of a special purpose pump (sorry I can't be
specific about its' function). and need to find some appx 3 inch dia X
1/4W acryllic tube. The ID needs to be round and smooth enough for a
sliding O-ring seal,similar to a hydraulic cyl. Pressure will be low,
about 20 psi. Does anyone know of any suppliers for a tube that fit the
need?

Have you tried McMaster-Carr?

On Thu, 10 Jul 2008 09:16:19 -0400, "Ed Huntress"
wrote:


"John Miller" wrote in message
om...
I'm working up a demo model of a special purpose pump (sorry I can't be
specific about its' function). and need to find some appx 3 inch dia X
1/4W acryllic tube.


Someone may prove me wrong here, but I can't see extruded acrylic tube being
round enough for a good seal.

Yes, I'd avoid extruded tube. McMaster carries cast acrylic tube which
should be good enough, depending on the the compliance of the seal.
Easiest way to find out is to buy a piece.

8486K557
(Same as 8486K555)
Clear Cast Acrylic Tube 3" OD X 2-1/2" ID, 1' Length
In stock at $23.88 Each.

--
Ned Simmons

"John Miller" wrote in message
m...
I'm working up a demo model of a special purpose pump (sorry I can't be
specific about its' function). and need to find some appx 3 inch dia X
1/4W acryllic tube. The ID needs to be round and smooth enough for a
sliding O-ring seal,similar to a hydraulic cyl. Pressure will be low,
about 20 psi. Does anyone know of any suppliers for a tube that fit the
need?

Thanks

--
J Miller

have you tried tap plastics?

On Thu, 10 Jul 2008 06:29:16 -0600, "John Miller"
wrote:

I'm working up a demo model of a special purpose pump (sorry I can't be
specific about its' function). and need to find some appx 3 inch dia X 1/4W
acryllic tube. The ID needs to be round and smooth enough for a sliding
O-ring seal,similar to a hydraulic cyl. Pressure will be low, about 20 psi.
Does anyone know of any suppliers for a tube that fit the need?

Thanks

Try Modern Plastics. My local branch in Warwick RI and they are
pretty good about helping me out when I am befuddled.

Errol Groff