© Edwards Limited 2012. All rights reserved.
Page 21
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Operation
A373-10-880 Issue R
4.3
Start-up
If the oil is contaminated, or if the pump temperature is below 13 °C, or if the electrical supply voltage is more than
10% below the lowest voltage specified for the pump, the pump may operate at a reduced speed for a few minutes.
On single-phase pumps, if the pump continues to operate at reduced speed, the motor thermal overload device will
open and stop the pump. When the motor has cooled, the thermal overload device will reset automatically and the
pump will restart.
1. Check that the pump oil-level is between the MAX and MIN marks on the bezel of the oil-level sight-glass; if it is
not, refer to
.
2. Turn the gas-ballast control to the required position (refer to
).
3. Switch on the electrical supply to the pump.
4. Check that the oil-level in the sight-glass drops slightly (by 3 to 5 mm) after start-up. This shows that the pump
has primed with oil.
5. If the pump fails to prime, operate the pump with the inlet open to atmosphere for approximately 30 seconds.
Then isolate the inlet and check that the oil-level drops by 3 to 5 mm.
6. If you want to achieve ultimate vacuum, to pump condensable vapours or to decontaminate the pump oil, refer
to the procedures in
respectively. Otherwise, open the vacuum system isolation-valve.
4.4
To achieve ultimate vacuum
If the pump does not achieve the performance specified in
, 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, refer to below) must be much lower than the specified ultimate vacuum
of the pump.
for a list of possible causes for failure to achieve the specified performance; note however
that the most common causes are:
Your pressure measurement technique or gauge head is unsuitable or the gauge head is faulty.
You have used an oil other than the recommended oil, and the vapour pressure of the oil is higher than 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 fully anti-clockwise (fully open) and operate the pump for at least 1 hour
(or overnight) to thoroughly purge the oil of contaminants.
3. Close the gas-ballast control.
4. Open the vacuum system isolation-valve and pump down to ultimate vacuum.
WARNING
Do not block the pump outlet or allow the outlet pressure to rise above 1.5 bar absolute. If you do,
the oil box may fracture and may cause injury to people nearby.
