Pump cartridge-type mechanical seals: need flush system?

[LaSalle1940]

The question is pretty much stated in the subject line: when using pumps with cartridge-type mechanical seals (the service is aqueous chemical solutions, some of which are acidic and others basic), are seal flushes required? Please note that these solutions do NOT contain abrasives or suspended solids.

My sense/recollection is that the answer to my question is "No, seal flushes are not required" but I'm not sure. Thanks.

 

[pmover]

please note this website for assistance:

http://www.gouldspumps.com/download_files/pump_fundamentals/gp_pf_apicpichart.stm

the purpose of seal flush is to avoid spillage of hazardous pumpage (solutions that are acidic or basic) into atmosphere and possibly to provide cooling to seal. upon seal failure, the fluid would flow into hte seal pot, whereupon activate either a pressure switch or level switch and deactivate the pump - provided a seal pot is installed.

although minimal information is provided, the pumpage is identified and certainly buyer and pump mfg should coordinate this matter to obtain a reliable and safe seal configuration.

good luck!
-pmover

 

[bimr]

Most mechanical seals require some sort of environmental control to function properly. Typical concerns:

Cooling to prevent a product from flashing or coking;
Heating to prevent a liquid from solidifying or crystallizing;
Flushing to wash away solid particles from the seal components;
Quenching to prevent crystals and ice from forming outboard of the seal interfering with its movement.

Intermittent service pumps have more problems with mechanical seals because the fluid can solidify, crystallize; become viscous, etc. when the pump is shut down.

The proper selection of a mechanical seal flush can be made only if the full operating conditions are known:

Liquid
Pressure
Temperature
Characteristics of Liquid
Reliability and Emission Concerns

 

[HEC]

LaSalle1940,
You have mentioned a cartridge type seal, these come in several flavours, double or single mechanical seals. The Single style does not require a flush as there is only one rotary seal face that is lubricated by the process fluid. The double mechanical seal does require a seal flush as there are two seal faces, an inner or process seal face and a outer or secondary seal. The inner seal is again lubricated by the process fluid. The outer eal requires the seal flush to lubricate it. The two seal faces are used to create a flush area. The purpose fort he flush area depends upon the application. For hazardous goods it is used for controlling emissions. In sanitary or sterile applications it is an environmental barrier.

Trust that this throws some light on the matter for you.


Mark Hutton