A705-61-880 Issue M
Page 32 © Edwards Limited 2012. All rights reserved.
Edwards and the Edwards logo are trademarks of Edwards Limited.
Maintenance
5.7 Change the gearbox oil and clean the oil-level sight-glasses
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 8. 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.
6. Clean all of the 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.
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.
Ensure that you do not come into contact with the used pump oil. The used oil may be hot and can
cause injury.
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 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.
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.
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