Small Rod Wipers? (Or other reliable gasket material?)

[BasketDaN]

I'm looking for a 1/8" diameter rod wiper, or anything else that could be reliably used to allow a 1/8" diameter steel rod to slide very slowly past it while maintaining cold oil (at about 0 celsius) on one side at several hundred psi, and standard pressure air on the other side.

Anybody know of somewhere I could find such a setup? I can't seem to find anything that small

Thanks
Dan

 

[Q_Goest]

Hi Basket. Rod wipers are typically not meant for sealing purposes. They're made to wipe dirt and other solid particulates off a rod prior to the rod going through a seal so as not to damage the seal. What you want is a seal of some kind.

Rod seals like this are typically O-rings, urethane cups, quad seals, Teflon U-cups or similar types of seals. They can also be purchased with Teflon wear bands if wear rate is a concern. Since you have oil on the pressurized side, and pressure is relatively low, you probably don't have to worry too much about wear of the seal.

If you need a specific recommendation, the first thing that comes to mind is to look on McMaster Carr. They don't have the urethane cups that small (I'm sure other places do) but they have various O-rings. I'd suggest part number 90025K513.
http://www.mcmaster.com/#90025k513/=2qxpr7

 

[BasketDaN]

Thank you very much! Good thing I didn't waste more time looking around for rod wipers.

O-rings are pretty easy to find; will they be fine for under 1,000 psi?

 

[Q_Goest]

The pressure that O-rings can be used at is primarily dependant on the material, how soft/hard it is, and any extrusion gap between the moving parts. O-rings at high pressure can be thought of as being a bit like a fluid in that they conform to whatever pocket they are contained in and will try to extrude into small clearances. Attached is a typical graph of extrusion gap versus pressure and hardness.

Also, the bible for O-rings is the Parker O-ring Handbook. Lots of great information in there, but it's a fairly large download.
http://www.parker.com/literature/ORD 5700 Parker_O-Ring_Handbook.pdf