Anyone mind helping me identify good plastic tubing for a specific application?

[lark1405]

Hi all,

Brand new to the forum with a question for you guys.

I'm looking for tubing that has some pretty specific properties that I haven't seen on too many charts. The tubing should be:

- a very small, extremely smooth, consistently sized hollow
- not 100% sure on this one, but a hydrophobic interior might be nice
- roughly a millimeter in total tube diameter
- low deformation in the tubing cross-section
- clear or translucent
- can create a low/moderate vacuum
- has moderate overall flexibility in the lengthwise direction
- has decent durability

Essentially, we want to flow a liquid at an extremely consistent pressure, which is why we don't want tube radius deformation and possibly hydrophobic properties. We are using peristaltic pumps, which is less than ideal. The tubing has to be flexible enough to move the liquid along through the tube, yet strong enough to endure some wear and tear.

The tubing only has to work from somewhere between 10 to 40 C, so that shouldn't pose too much of a problem.

I know this is a pretty tall order in terms of details, but if anyone has suggestions for references or resources I'd really appreciate it.

 

[MikeHalloran]

You will never get a peristaltic pump to do what you want.


Mike Halloran
Pembroke Pines, FL, USA

 

[hendersdc]

I agree with Mike, peristaltic pumps move slugs of fluid creating waves of pressure not constant precise pressures. Tubing must be very flexible for use with a peristaltic which may also cause problems with your "low/moderate vacuum" depending on what you mean by that as flexible tubing will deform and change in its cross sectional area under vacuum.

 

[lark1405]

Yeah, I was afraid of that. We're planning to leave peristaltic on the next iteration of out equip, but who knows when that will occur...

 

[btrueblood]

Do you want this tubing to work within the peristaltic pump, or downstream of the pump?

Within the pump, silicone, preferrably platinum cured. Realize that ANY tubing within the pump will have a finite life (due to fatigue), that life being roughly 1/3 of what you can stand it to be.

Outside the pump, or for use with a better pump, PFA tubing.

 

[lark1405]

We feed our tubing (polypropylene or polystyrene) directly through/within the peristaltic pump. We already know about the finite thing, and change our tubing every 1-2 weeks depending on usage.

What's the benefit of si/pt tubing?

We have approximately 10 inches of tubing outside the pump as linker. Again, why would pfa be a good choice here?

Thank you so much for the help!

 

[btrueblood]

Silicone tubing has a naturally hydrophobic surface, and platinum curing gives much better crosslinking and subsequent fatigue life.

PFA also has a naturally hydrophobic surface, and has very good strength for a given wall thickness, and good kink/crack resistance compared to your other two tube types (or PE tubing). Nylon comes closer.

I'd not use any thermoplastic as a peristaltic pump tube, and am surprised you even get two weeks with the tubes you list.