Vacuumpump Benco Info needed

Dear forummembers,

I've bought a vacuuumpump recently and need some advice.

Pump is a Benco C4. Who can date this pump? (Year of manufacturing)
At the front cover a so called  Stefa seal (nr. 2047) is mounted.     How to remove this and where to buy spares?
There is no gasket mounted between the housing and the front cover.     Is this normal? If not can I use liquid gasket like Loctite?
RPM 450 is marked in the casting.     Is this maximum?  
On the type plate BP Energol HL80 is prescribed.    What is usable as substitute?

See some pictures below




Please let me know your thoughts

Best regards,

Steef Pronk

Not familiar with that make of pump myself, Manus is the more usual Swedish make found in the UK, however there are normally no gaskets or sealer fitted to vacuum pumps as the rotor needs a close tolerance to work properly. The rpm seems correct for that pump, the vane type run a lot faster. It looks very similar to my old Alfa Laval pump and I just used hydraulic oil in that.

Pete.