Municipal Wastewater Pumps- Seal Mat'l Recommendations

[piffer]

I'm looking for expert opinions on recommended seal face materials for sewage pumps (pros/cons).
Tungsten-carbide vs. Tungsten-carbide or silicon-carbide vs. silicon carbide

 

[longeron]

My answer is that it depends. What kinds of liquids and solids are in the process?

You don't have to use the same seal face material for both the primary and mating rings. Seals usually perform better when one face is harder than the other, something has to wear. I am biased against using Tungsten against Tungsten, as I believe it tends to generate too much heat. However, I don't feel the same about Silicon Carbide against itself.

 

[acp]

Piffer

I agree with longeron for the use of SIC Vs SIC.For Stationary face you can use Alfa Sintered SIC and for roatary face use Purbid Gr.SIC of Pure Carbon.This face
combination will give you best results.

ACP

 

[RAKESHBHATIA]

Hi

Are you using single or double seal for this application.

If you are using single seal go for SIC/SIC seal faces and if possible with clear water flush.

If you are using double seal , inboard seal ( process side ) should be with SIC/SIC seal faces and outboard seal can be carbon/sic seal faces.

Send me any other query you may have on mech seal.

Rakesh.

rakesh@burgmannme.com

 

[piffer]

Thank you Longeron, ACP, and Rakesh for your replies. Specifically, I was curious about pros/cons of TC vs. TC and SIC vs. SIC in sewage service. Some pump manufacturers furnish TC and others furnish SIC in their standard products.

 

[alrai007]

As far as my knowledge about sealing goes TC Vs TC face combination has a very low PV ratio and hence is to be avoided as far as possible.secondly it is always preferable to have one hard and other comparatively softer face and hence Sic Vs TC is a much better option.I beg to differ with ACP, as the application u r talking about is muniocipal waste and hence carbon face is not the correct choice.
sic vs tc with plan 32(external pressurised clear liquid flushing )shall give you a much better MTBF.
kaushal

 

[piffer]

For my original inquiry, I was assuming submersible pumps. The common seal arrangements are tandem or double seals, operating in a static oil housing (no seal flush). I came from the API pump world, so I am learning about submersibles. As their seals are continuously lubricated (operating in oil housing), some submersible pumps can run dry witout damaging the seals. I was curious about pros/cons of tungsten-carbibe vs. tungsten carbide compared to sil-car vs. sil-car when operating in sewage.

 

[tmack]

I am also looking to confirm that SiC/SiC is superior to WC/WC (or WCCR/WCCR as it is sometimes ref'd). So far see St. Gobain website:

http://www.hexoloy.com/applications/seals.html

- 19k for comparison. Disclosure: my company, EBARA, uses SiC/SiC as primary seal of double/tandem seals as our standard for our submersible pumps.