Welch Vacuum 2047 Dryfast & Dryfast Ultra - Manual (Page 11)

11
Section 4: MAINTENANCE
4.10 General Maintenance
Welch Dryfast Vacuum units are 100% oil-free. The pump employs a diaphragm with an
uninterrupted PTFE coating. All bearings are sealed and permanently lubricated. Lubrication
should not be attempted. The units are built for duty operation just like a water aspirator, but
with the quietness, performance and durability of a diaphragm.
4.11 Diaphragm Removal
WARNING
Do not remove the diaphragm unless you are wearing hand protection. The
steel disc inside the diaphragm may cause harmful injury.
1. Remove the four 4M x 45 screws and washers from the cover plate. Remove the cover plate
and head from the plastic head base.
2. Make sure to wear gloves before removing the diaphragm. Grab the diaphragm with both
hands and turn counterclockwise to loosen from connecting rod.
3. Remove the diaphragm retaining shims.
4.12 Installation of New Diaphragm
1. Apply a minute amount of locktite to threaded diaphragm stud and fasten to connecting rod
with shims previously removed.
2. Tighten diaphragm with both hands. Tighten eccentric set screw down on to the fl at of the
motor shaft.
3. Place the head and chamber assembly on top, rotate fan so that the peripheral lip of the
diaphragm aligns with the groove on the underside of the chamber and base plate.
4. Place the cover plate over the head and body using four 4M x 45 screws and washers.
Tighten the bolts (no more than 20 inlb.) or PTFE will deform.