"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