O-Ring Grooves

[Boucher]

I need to make some special fittings to allow rotation between parts aprox 1/2" dia. with normal water pressure (Max 75 psi). How would you machine the groove if it were on the od of the piece or if it were on the face of a flange surface? How critical are the dimensions at these conditions?

[oldtiffie]

Will this help?

This might help:
http://www.applerubber.com/

http://www.google.com.au/search?hl=e...e+Search&meta=

[PaulF]

This is called a dynamic seal.
Go to the Parker web site.
You do need a dynamic seal if things move like shafts or couplings.
Paulf

[barts]

I need to make some special fittings to allow rotation between parts aprox 1/2" dia. with normal water pressure (Max 75 psi). How would you machine the groove if it were on the od of the piece or if it were on the face of a flange surface? How critical are the dimensions at these conditions?

O-rings will work nicely. Rubbing surfaces need to be very smooth to prevent quick wear; reducing the diameter of the o-ring will reduce velocity, producing longer life. Groove finish is also important to prevent rapid wear.

Groove dimensions aren't super critical at low pressures, holding .005 tolerances is pretty easy w/ a lathe bit ground to the right size. Clearance
between rubbing parts should be small - no more than .003" or so, or
the O-ring gets squeezed into the gap.

Keep in mind the consequences of failure vs cost of perfection; a leak in a lawn sprinkler is less critical than a computer water cooling system :-).

http://www.efunda.com/designstandard...ring_intro.cfm

- Bart