Regarding Mechanical Seal Basics 1

[HoustonMechEngr]

I've never seen an answer to the question regarding why one face must rotate and why the other is stationary. I've always believed the best explaination as to why one face rotates is to generate a hydrodynamic seal by both viscous shearing and heat generation to "flash" off visible leakage. Thoughts?

 

[flexibox]

There must always be a stationary face and a rotating face with a rotating shaft. The stationary face is mounted inside a gland plate which is bolted to the Seal Chamber. The rotating face MUST rotate because if it were stationary the Oring seal between the shaft and rotating face will be shredded and a lot of friction will occur with metal parts rubbing.
So the rotating face rotates with the shaft at whatever speed it is doing. A fluid film is formed between the faces and heat is generated at the seal faces. This is why we have different piping plans to disapate the heat.

If the shaft was static then you do not need a mechancial seal you can have a housing with an Oring seal.

i trust that this is clear for you.