BOC Edwards EO2K, Instruction Manual

Page: 32 / 62

EO2K, EO4K and EO6K Diffusion Pumps
IN
STALLATION
PAGE
26
Issue G 26 Aug 06
3.7 Connect the cooling-water pipelines (water-cooled pumps only)
The minimum cooling water flow given in Section 2.5 is calculated for a 10
o
C temperature rise. Thus,
with a high water inlet temperature, it may be necessary to increase the flow to maintain the outlet
temperature below 35
o
C. Do not exceed this temperature, otherwise a thermal snap-switch (if fitted)
may operate to switch off the pump, and fluid loss to the backing pipeline will increase.
Use the formula below to calculate the minimum required cooling-water flow for the pump:
F = (3600 x 0.9 x P
h
) / [4200 x (35 - T
w
)]
where:
Note that:
• 90% of heater input power is transferred to the water supply (the balance is lost as radiant heat
from the pump surfaces)
• The cooling-water used must contain no additional additives that may affect its cooling properties.
• The outlet temperature must be no higher than 35
o
C
• The calculated value gives an absolute minimum water flow rate. We recommend that the water
flow rate is at least 20% higher than this minimum flow rate.
High cooling-water temperatures should not have any appreciable effect on pump performance except
to increase the vapour pressure of the fluid, which will limit the ultimate vacuum that can be obtained.
We recommend that the cooling-water supply is filtered and that a flow indicator is incorporated into
the supply system.
Refer to Figure 14. Connect your cooling-water supply pipeline to the pump cooling-water inlet (1) and
connect your return pipeline to the pump cooling-water outlet (2). Use
1
/
4
inch BSP fittings or
3
/
8
inch
BSP fittings suitable for the connections on the pump (see Table 3).
WARNING
Do not fit quick-fit couplings to the pump cooling-water inlet and outlet. Use of these
couplings can result in trapped volumes of water. This water may boil, the cooling-coil
may fracture and hot water and steam ejected from the cooling-coil may injure people.
CAUTION
Ensure that the cooling-water flows in the correct direction. If it does not, there will be increased
backstreaming and loss of performance, which may have an adverse effect on your process.
F is the minimum required cooling-water flow (in l h
-1
).
P
h
is the heater power (in W).
T
w
is the cooling-water supply temperature (in
o
C).