Instruction manual

Oct 04 Issue H
GV Dry Vacuum Pumps
PAGE
23
23
OPERATION
4OPERATION
The procedures in the following sections assume
that you have a pump inlet-isolation valve fitted to
your pump.
4.1 Start the pump
Use the procedure below to start the pump.
1. Check the gearbox oil-level in the sight-glass on
the side of the pump: refer to Section 3.5.
WARNING
Take all necessary safety precautions
when you pump toxic, flammable or
explosive gases. If you do not, there
will be a danger of injury or death to
people.
WARNING
During operation, some parts of the
pump become hot; these areas are
identified by ‘hot surface’ labels (see
Section 1.1). Do not touch these
areas of the pump, and avoid
accidental contact between these
areas of the pump and electrical
cables and wires, and so forth.
WARNING
Do not operate the pump with a
coupling cover removed. If you do,
there will be a danger of injury or
death from the rotating mechanisms.
WARNING
Do not operate the pump with the
pump-inlet or pump-outlet open to
atmosphere. If you do, there will be a
danger of injury or death from the
rotating mechanisms, from the
exposure to vacuum, or from hot
exhaust gases.
2. Turn on your cooling-water supply, shaft-seals
purge air or nitrogen supply, gas-ballast
nitrogen supply (if fitted) and exhaust-
extraction system (if fitted).
3. Switch on the pump.
4. Continue at Section 4.2 to allow the pump to
warm up.
4.2 Allow the pump to warm up
Leave the pump to operate (with the inlet isolation-
valve closed) to allow the pump to warm up to its
operating temperature:
• Without inlet purge, warm-up takes
approximately 30 to 45 minutes, depending
on the ambient temperature.
• With an inlet purge pressure of 50 to 250
mbar (5 x 10
3
to 2.5 x 10
4
Pa, 37.5 to 188
torr), warm-up time can be reduced to as
little as 10 minutes.
When the pump has warmed up to its operating
temperature, you can start process pumping. In the
first 30 seconds of pumpdown, open the inlet
isolation-valve slowly if there is liquid in the inlet
pipeline, in order to minimize the ingress of liquid
(entrained in the process gas stream) into the pump.
CAUTION
Allow the pump to warm up and use full gas-ballast
and inlet purge (if fitted) before you pump
condensable vapours. If you do not, the vapours
may condense in the pump and corrode or damage
the pump.