seal flush iping plan & quench

[farahnaz77]

I'd like to know about seal flushing and quench system used for a centrifugal pump. I have studied API 610, app.D, but I'd like to know how and based on which condition a seal flush plan is selected. when a quenching is also required?
Thanks in advance

 

[Montemayor]

farahnaz77:

Before you start to select or evaluate centrifugal pump mechanical seals, I strongly advise you to obtain and read the background material on how the mechanical seal is designed and classified - such as the excellent "Dura Seal Manual" issued by Durametallic Corp. of Kalamazoo, Michigan; USA.

It is imperative that you understand the fundamentals of mechanical seal operation and design before you undertake to select the proper type of seal flushing to be employed. There are mechanical seals and then there are "other mechanical seals":

1) Seals can be single or double;
2) Seals can be pusher or non-pusher seals;
3) Seals can be balanced or unbalanced;
4) There are Inside seals, Outside seals, Double seals, Tandem seals, Cartridge seals, etc., etc.

So before you even contemplate which API Plan you should use in your application and which fluid is adequate, you should know exactly what you are applying it on.

I'm afraid a tutorial on mechanical seal flushing is not going to be efficiently obtained on this forum. Now, if you ask a specific question on a specific application and supply all the basic data and information required, then we can supply you with recommendations - but you would be well advised to be thoroughly knowledgeable in mechanical seal design and operation in order to decipher what the experienced responses will say. So my recommendation of studying the Dura Seal Manual still stands.

Good Luck.


Art Montemayor
Spring, TX

 

[Scipio]

A couple things to add,

1. Durametallic is now owned by Flowserve, and I think they stopped publishing that handbook. If you can find one, Montemayor's right, it's a great book. I 'inherited' mine from an engineer who was cleaning out his bookshelf. One good one if you're starting from scratch on seals is "Mechanical Seal Principles Manual", published by Chesterton,

http://www.chesterton.com.

2. Be careful referencing API 610 for seal info - when API 610 9th edition came out in 2003, they extracted everything relating to seals, including Appendix D. 9th edition defers to API 682 for seal requirements. Technically the seals are no different, all the seal flush/barrier/quench plans are numbered the same, but the old API 610 seal coding (i.e. "BSTFN") is being phased out in favour of 682's coding terminology. Also, it requires balanced construction in all seals, so there's no such thing (supposedly) as an unbalanced API 610 pump seal as of 9th edition. That said, every pump & seal vendor I deal with still knows the old pre-9th edition codes and uses both on quotations.

 

[checman]

Farahnaz, Montemayor is right there are many types of mechanical seals. And most require being supported by some sort of flush. Seal flushes can be the product being pumped or from an outside source or both product and an outside source. You can raise or lower the seal housing pressure or just create flow, it all depends on the application and the equipment. Two common flush plans on single mechanical seal are the API 11 from the pumps discharge and the API 13 from the pumps suction. On the API 11 you are normally putting product from the discharge to the seal chamber and back into the casing. On the API 13 you are taking the liquid from behind the impeller running it through the seal chamber and then back to the pump suction. Beside the pressure difference the API 13 may supply cleaner product if the product being pumped has heavy abrasives in it. The 13 fluid comes from behind the impeller around the shaft area where centrifugal forces from the impeller may have thrown the heavy particulate to the outside of the casing. This is just a drop in the bucket when it comes to seal flushes. Unfortunately I do not think the Dura seal manual is still available. Dura is now part of Flowserve.

A seal Quench is a product supplied to the atmospheric side of a mechanical seal (such as cool water). A water quench can help reduce the amount of heat transmitted from a hot product being pumped to the pumps bearing frame. A steam or water quench can be used to keep product from oxidizing or reacting with oxygen on the atmospheric side of the seal faces by replacing the atmosphere with steam or water. The oxidized product can hang the seal up ( keep it from adjusting to shaft movement) causing a leak. Those are some of the most common uses of a seal quench. But there are many other uses for quenches such as a steam quench to keep the seal faces warm on temperature sensitive applications like pumping asphalt. It would keep the faces from being glued together by the asphalt when the pump is shut down.

Good luck in finding a good source for information!

Regards Checman

 

[farahnaz77]

thanks all for your useful advices.