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Double Seal Vs Single Seal 2

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1ton

Mechanical
Joined
May 5, 2003
Messages
25
Location
MY
Does anyone knows when do we choose double over single seal. Advantage over the other. Any intresting artical on this subject.

Thanks
1ton
 
A single seal is generally used when it is acceptable for the process fluid to leak to atmosphere! As with oil duties, no hydrocarbon can leak to atmoshpere, hence a double seal with higher barrier fluid pressure is used. This way fluid leaks to process and atmos.

Mechanicals sealing does not provide 100% Leak free operation.
 
Viscous Crude Oil
 
Single Seal OK
SiC v SiC Faces, Viton O Rings
Plan 11 ReCirc Line advised

However, is there any salt water in the crude ?
What is the temperature ?




-
Milkboy
 
It depends. There isn't an easy answer- unless of course the process fluid is toxic... Often times a tandem seal with an unpressurized buffer fluid is enough to keep emissions down.

As Milkboy suggested, a single seal might do the trick. SiC vs Sic could work, so could SiC and Tungsten. There are some old school materials that work well here too.

I'm working on upgrading a pump that is severely abused and am suggesting that a particular kind of dual seal be used to ensure that when the pump is abused that the seal sees a nice clean atmpsphere.
 
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