Instruction manual

Issue H Oct 04
PAGE
30
GV Dry Vacuum Pumps
MAINTENANCE
30
5. Clean the inside of the exhaust manifold (3) to
remove any deposits; if necessary, use a suitable
cleaning solution. If you use a cleaning solution,
ensure that all of the solution is removed before
you fit the new interstage relief valve
componentts.
6. Inspect the 'O' rings (8, 5, 4) and, if necessary,
fit new 'O' rings.
7. If necessary, refit the two hinge bushes (1) to
the valve flap (7), then fit the valve flap to the
valve body (2).
8. Refit the valve body (2) in the exhaust manifold
(3).
9. Fit the retainer (9) to the exhaust manifold (3)
and secure with the four bolts (11). Tighten the
bolts to a torque of 10 Nm (7.4 lbf ft).
5.7 Change the gearbox oil and clean the
oil-level sight-glasses
WARNING
The pressure in the gearbox will be
equal to the pressure of your shaft-
seals purge gas supply. Loosen the oil
filler-plug and wait for two or three
seconds for the pressure in the
gearbox to equalise before you
remove the oil filler-plug or oil drain
plug. If you do not, oil may be ejected
under pressure from the gearbox.
WARNING
Ensure that you do not come into
contact with the used pump oil. The
used oil may be hot and can cause
injury.
Refer to Figure 1. You must clean the oil-level sight-
glasses (14) when you change the gearbox oil. Use
the following procedure to clean each sight-glass.
1. Refer to Figure 10. Remove the oil filler-plug
(12) and bonded seal (13).
2. Place a suitable container under the oil drain-
port (5); ensure that the container has sufficient
capacity for the oil in the pump (see
Section 2.6).
3. Unscrew and remove the oil drain-plug (3) and
the bonded seal (4) and allow the oil to drain
from the gearbox. Dispose of the ‘O’ ring.
4. Undo and remove the four M5 screws (11)
from the sight-glass bezel (10) on one of the oil-
level sight-glasses.
5. Remove the bezel (10), ‘O’ ring (9), sight-glass
(8),’O’ ring (7) and compression ring (6).
Dispose of the ‘O’ rings.
(Continued on page 32)
WARNING
Changing the oil in a pump from
hydrocarbon to PFPE (Fomblin)
could potentially cause a safety
hazard. Fomblin pumps are generally
used in hazardous applications which
may involve the pumping of gases
with high concentrations of oxygen. If
hydrocarbon oil comes into contact
with gases with an oxygen
concentration greater than 25%, an
explosion can occur.
Therefore, if you want to convert a
pump that has been used with
hydrocarbon oil to use PFPE
(Fomblin) oil, you cannot simply flush
the pump with new PFPE oil. You
must return the pump to a BOC
Edwards Service Centre for overhaul
and cleaning by qualified BOC service
engineers. The change in oil type
requires a complete strip down of
the pump, and thorough cleaning of
all parts, so that all traces of
hydrocarbon oil are removed.