A705-74-880 Issue K
Page 36
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MAINTENANCE
5.8
Change the gearbox oil and clean the oil-level sight-glasses
. 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
. Loosen the oil filler-plug (12) and wait for two or three seconds for the pressure in the
gearbox to equalise before removing together with the O-ring (13) from the oil filler port (1).
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
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 bonded seal.
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.
6. Clean all sight-glass components and the sight-glass recess in the gearbox (2) with a soft lint-free cloth. If
necessary, use a suitable cleaning solution; if you use a cleaning solution, ensure that all of the solution is
removed before you reassemble the sight-glass.
7. Refit the compression ring (6) in the sight-glass recess in the gearbox (2).
8. Fit two new O-rings (7, 9) and the sight-glass (8), then fit the bezel (10) and secure with the four M5 screws (11).
9. Place a suitable funnel in the oil filler-port (1).
10. If the oil drained from the pump is very discoloured, flush the gearbox with new or clean oil two or three times,
until the oil which drains from the gearbox is clean.
WARNING
The pressure in the gearbox will be equal to the pressure of the shaft-seals purge gas supply.
Always equalise pressure before removing the oil filler-plug or oil drain plug to avoid oil being
ejected under pressure from the gearbox.
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
an Edwards Service Centre for overhaul and cleaning by qualified Edwards 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.
WARNING
Particular caution should be exercised when working with Fomblin oil that may have been exposed
to temperatures above 260°C. Refer to the Edwards Materials Data Sheets for detailed
information.
WARNING
Ensure that you do not come into contact with the used pump oil. The used oil may be hot and can
cause injury.
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