A344-02-880 Issue J
Page 22 © Edwards Limited 2007. All rights reserved.
Edwards and the Edwards logo are trademarks of Edwards Limited.
Operation
4.3 To achieve ultimate vacuum
If the pump does not achieve the performance specified in Section 2, make sure that this is not due to your system
design before you contact your supplier or Edwards for advice. In particular, the vapour pressure of all materials used
in your vacuum system, including pump oil, must be much lower than the specified ultimate vacuum of the pump.
Refer to Section 5.13.2 for a list of possible causes for failure to achieve the specified performance. The most
common causes are:
z Your p r e s s ure me a s u r ement t e chniqu e o r gaug e h e ad is u n s uitabl e o r the g a u g e head i s faulty
z You hav e used a n oil ot h e r than t h e recomm e n d ed oi l , a nd the v apour p r e ssure o f t he oil i s higher t h a n the
specified ultimate vacuum of the pump
Use the following procedure to achieve ultimate vacuum:
1. Isolate the pump from your vacuum system.
2. Turn the gas-ballast control (Figure 9, item 4) fully anti-clockwise (fully open) and operate the pump for at least
1hour (or overnight) to thoroughly purge the oil of contaminants.
3. Close the gas-ballast control (Figure 9, item 4).
4. Open the vacuum system isolation-valve and pump down to ultimate vacuum.
4.4 To pump condensable vapours
Use gas-ballast when there is a high proportion of condensable vapours in the process gases.
1. Close the vacuum system isolation valve.
2. Turn the gas-ballast control (Figure 9, item 4) anti-clockwise to fully open and operate the pump for 30 minutes
to warm the oil. This will help to prevent vapour condensation in the pump.
3. Open the vacuum system isolation-valve and continue to operate the pump with the gas-ballast control open.
After you have pumped condensable vapours, you can (if necessary) decontaminate the oil. Use the procedure in
Section 4.5.
4.5 To decontaminate the oil
The oil in the pump should be clear. If the oil is cloudy or discoloured it is contaminated with process vapours.
1. Look at the condition of the oil in the sight-glass (Figure 1, item 7). If the oil is cloudy or discoloured, continue
with the procedure at Step 2 below.
2. Close the vacuum system isolation-valve.
3. Turn the gas-ballast control (Figure 9, item 4) fully anti-clockwise.
4. Operate the pump until the oil is clear.
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