Ever wonder why there are so many seal types? And what each seal type is actually used for?
Below is a quick guide to the purpose and function of each seal.
An expeller seal is a shaft seal where an expeller, or rotating part, is installed where mechanical seals or gland packing are normally placed. It looks similar to another impeller. The rigid vanes are mounted at the rear of the disc. As it rotates, the shaft pressure is reduced, creating a dry seal around it without any packing or gaskets. You can find out more about expeller seal pump via https://www.schurcoslurry.com/slurry-pumps/severe-duty-slurry-pumps/s-series-lined-slurry-pump/.
Single mechanical seal
This is the most commonly used seal. It seals the pump head. The liquid is kept inside the pump head. There are several components of the seal. The rotating shaft rotates and the stationary shaft cools it. A spring keeps the seal compressed and airtight.
Double mechanical seal
Two mechanical seals can be found within a pump. As per the standard mechanical seal, the first seal keeps the fluid inside the pump. The second seal has a barrier fluid that keeps the faces clean and prevents them from leaking. The mechanical seals could fail if they are not lubricated with a barrier fluid.
Before a mechanical seal is inserted into a pump, it should be checked that the clearances are correct. Pre-assembled cartridges eliminate the need to set clearances.