Instruction manual

EXT Split Flow Compound Turbomolecular Pumps
INSTALLATION
PAGE
18
Issue F 18 Mar 07
3.6 Cooling
3.6.1 Introduction
You must use water-cooling in addition to forced air cooling in any of the following operating conditions:
Backing pressure > 10 mbar.
Backing pressure > 8 mbar (800 Pa) and interstage flow > 30 sccm (0.5 mbar.ls
-1
, 50 Pa.ls
-1
).
Backing pressure > 5 mbar (500 Pa) and interstage flow > 80 sccm (1.3 mbar.ls
-1
, 130 Pa.ls
-1
).
Ambient temperature > 35
o
C.
In all other operating conditions, you can use forced-air cooling only. If you use forced-air to cool the
pump, you must ensure that there is an adequate supply of cooling-air to the pump.
During operation, if the temperature of any surface of the pump is higher than 45
o
C, the pump is too
hot and you must increase the cooling.
3.6.2 Forced-air cooling
An air-cooler accessory is available for the EXT Split Flow Pumps (refer to Section 7). Fit the air-cooler
as described in the instruction manual supplied with it. If you wish to use an alternative fan for air-cooling,
ensure that the flow rate is above 70 m
3
h
-1
(40 cfm).
3.6.3 Water-cooling
A water-cooling block accessory is available for the EXT Split Flow Pumps (refer to Section 7). Fit the
water cooling block as described in the instruction manual supplied with it. The cooling-water supply
must comply with the specification given in Section 2.4. Pipes in the water-cooling circuit may become
blocked if the cooling-water contains too much calcium carbonate or if it contains particulates which are
too large. Corrosion of the water-cooling circuit may occur if there is too little calcium carbonate and
oxygen in the water. Good quality drinking water is usually suitable for water-cooling. If in doubt, you
must check the quality of your cooling-water supply and, if necessary, provide treatment and filtration.
Connect the cooling-water supply to the water-cooler on the pump as described below. Either of the
two riffled connectors on the water-cooler can be used for the water supply or return connections.
1. Push reinforced hose (approximately 6mm internal diameter) over the ends of the riffled hose
connectors on the water-cooler on the pump.
2. Attach the hose with strong hose clips and make sure that they are tightened securely.
You must turn off the cooling-water supply when you switch off the pump to prevent condensation of
vapours inside the pump. The EXC Controller (EXC120 and EXC300) can operate a solenoid-valve for
this purpose.
If you want to remove the pump for maintenance, and you do not want to break the cooling-water circuit,
unscrew the M4 cap-head fixing-screws and remove the water-cooler from the pump. Make sure that
there is a layer of thermal contact grease on the water-cooler before you refit it to the pump.
CAUTION
You must cool the pump by forced-air or water cooling to prevent damage to the bearing.