To seal or not to seal We are in

[rhc]

To seal or not to seal

We are involved in an R&D project. Part of the project requires that a seal isolates fluid from the inner chamber to the outside.
Fluid = water + fine abrasive particles
Shaft dia = 100mm
Carrier = 120mm
Len = 50mm
rpm = 1000 ~ 6000
Fluid pressure = 100 psi

We were advised early on that contact lip seals would not work at the high rpm end. At the moment we are looking at a non contact "seal" which relies on extremely fine clearance between the respective nonrotating and rotating surfaces. To protect the seal surfaces the abrasive particles are supposed to be flushed with clean water.

Any suggestions?

 

[hero123]

what is the question? what do u want the suggestions for?

 

[rhc]

To hero123

If you have direct experience and can provide practical information about a high rpm seal that will work in the 100mm x 120mm x 50mm space we have available we would appreciate.
The shaft rotates, the carrier does not

 

[rkinga2]

Is anyone familiar with a pressure-relieving flange gasket?? It reportedly fits between pipe flanges like a regular gasket, but blows out if pressure reaches a given level.

 

[tstead]

RHC,

What you need is a double mechanical seal with a buffer fluid between the two seals at a slightly higher pressure than the pressure in the seal chamber such that the buffer fluid leaks into your pump. This assumes, of course, that your process fluid can accept dillution.

Like always, contact the pump manufacturer or a seal manufacturer. You might be stuck with going to the pump mfgr and paying their outrageous price for a non-standard seal because they probably won't part company with their seal chamber drawings. If you had the seal chamber drawing, you could send that to any seal mfgr (Chesterton, Crane, Burgmann, Flowserve, etc.) and get a price on a better seal at a better price than what the pump mfgr would give you.

Did I mention that the pump mfgr would probably just contact the seal mfgr and ask their recommendation for a seal?

Bypass the middle man and save some dough.

Tim

 

[longeron]

RHC,

Check out the following link:

http://www.gouldspumps.com/download_files/literature_misc/Taperbore_brochure.pdf

This will give you an idea of what most mechanical seal guys imagine in their heads when the think of the chamber that holds a mechanical seal.

Most of the major seal mfgs (John Crane, Flowserve, Chesterton, Burgmann and so on) will be happy to engineer a seal for your application.

There is a series of pumps made by Sundyne that are designed to operate at high rpm (even higher- 33,600 rpm), just as your application does. Again, most of the major seal mfgs have considerable experience with these pumps. Your pressure is not very high, the process fluid you describe is also something that is not to unusual. I am fairly certain that once you contact your local seal vendor that they will be able to engineer something satisfactory.

Is there a reason you mentioned a non-contacting seal? There are dry gas seals, or bushing type seals, that may work here as well as the double seal mentioned. It depends upon the application and the manner of support system that you are able to accomodate.