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john hobdeclipe
12-22-2009, 09:30 PM
If I want to use an o ring or an oil seal to seal against low pressure water loss around a rotating shaft, do I need to specify anything unique as far as seal design or material?

This will be light duty...say a 3/4" shaft at no more than 800 rpm and about 10 or maybe 20 pounds of water pressure.

HSS
12-22-2009, 09:37 PM
John,
Is there any way you can use a mechanical seal like US seal? An O'ring prolly won't last. www.ussealmfg.com Or maybe if you have a spa and pool supply they carry those seals. If you don't want to go to a mechanical seal then you could maybe use a mechanical packing. :rolleyes:

Patrick

Black_Moons
12-22-2009, 09:47 PM
http://www.rlhudson.com/O-Ring%20Book/designing-tables.htm this page here might help you reguarding the proper dimentions to turn everything to for the seal type you need. Im not sure about the rpms and such..

Ken_Shea
12-22-2009, 09:55 PM
Patrick,
Believe you may be underestimating the longevity of the humble little o-ring :)

HSS
12-22-2009, 10:19 PM
I don't care much for orings in a rotating application. They work ok at first but will wear out. In a stationary application they are great and I use them for that. Even in an ice machine where there is rotation and no water pressure the bearings are sealed with a mechanical seal and the evaporator shell is sealed with an oring, but the shell doesn't rotate. Just my .02 worth.;)

Patrick

Ken_Shea
12-22-2009, 10:31 PM
In that application your advice is worth more the 2cents.

Carld
12-22-2009, 10:47 PM
Well, if you use an O ring make it easy to replace it but a lip seal will outlast an O ring.

john hobdeclipe
12-22-2009, 10:47 PM
The device I want to make is a "water swivel" adapter to feed water down the hollow shank of a small (1/2" or less) diamond core drill. Here are a couple of examples:

http://www.hisglassworks.com/cart/cart.php?m=product_detail&p=75

http://www.glasstool.cn/bookpic/200881420445592616.jpg

I'm thinking along the lines of "E1" in the second link...to accept straight shaft drills.

I wonder what they use for sealing?

Evan
12-22-2009, 10:51 PM
I wonder what they use for sealing?

Perhaps nothing? Does it matter if it leaks a bit at that pressure?

Carld
12-22-2009, 11:13 PM
It looks simple enough to make one and since the water is needed for the cutting I would put a seal or a O ring at the top where the stub shaft is and let the water come out the bottom all it wanted to.

darryl
12-22-2009, 11:55 PM
Lip seals aren't hard to find, and they do the job. If you're going to use an o-ring, maybe consider using two with a spacer between them- you would fill the gap between them with o-ring grease. Probably the more important thing is the finish on the shaft where the seal will ride.

flutedchamber
12-23-2009, 12:14 AM
Try a quad ring seal. Usually the same place that sells Orings sells quad rings. That way you have 2 edges sealing everything.

black powder
12-23-2009, 01:05 PM
Most all small rotary unions use "o"rings for seals .A quad ring will also work,previsions for lubing either must be made .