Why Mixer and Agitator Seals?

Mixer and agitator seals are similar to pump seals with one major exception, they are more prone to shaft runout. The reason is the generally long shaft extension that gives the shaft leverage against bearings and seals. One solution is to mount the seal faces in a fashion that allows run out. BURGMANN seal is unique in that the dual seal rotary seal faces run next to each other against a single stationary. This is a very unique design that permits far more runout than traditional single cartridge or double cartridge seals . If the shaft is short or very well supported by ultiple bearings restriciting runout, BURGMANN seal may not be necesssary.

Another issue with Agitator and mixer seals is they often do not receive lubrication. In the right conditions a mechanical seal can operate dry but key issues must be considered:

How much heat is being generated by the seal faces? The speed of the shaft and the materials of construction of the mechanical seal are of even greater importance than a flushed/lubricated seal.
The best combination of seal faces is Carbon Vs. Silicon carbide due to the low friction generated between these two faces. Glass filled PTFFE faces are another potential solution.

Chemical compatibility of the product being sealed must of course be considered.

If conventional double seal with environmental controls are utilized caution must be taken to be certain enough lubrication is provided without contamination of the product being mixed.