BOC Edwards 18B4B, Instruction Manual, Page: 30 / 62

Issue A Feb 04
PAGE
24
18B4B Vapour Booster Pumps
IN
STALLATION
24
3.8 Connect the thermal snap-switches
3.8.1 Connect the cooling-fail thermal
snap-switches
The cooling-fail thermal snap-switches protect the
pump against damage due to failure of the cooling-
water supply. If the temperature of the pump
cooling circuit increases above the normal operating
level, the snap-switch contacts will open.
You must connect the thermal snap-switch contacts
to your pump control circuit (see Figure 10) so that
the electrical supply to the pump is switched off if
either of the thermal snap-switch contacts open
The thermal snap-switches automatically reset when
the temperature of the pump returns to normal.
Incorporate an interlock so that the electrical supply
to the pump is not automatically restored when the
snap-switches reset.
The operating temperature of the cooling-fail
thermal snap-switches is preset for use with AP201
pump fluid. If you want to use other fluid types in the
pump, contact your supplier or BOC Edwards for
advice.
Note: The cooling-fail thermal snap-switches may be
wired in series with the boiler protection
thermal snap-switch (see Section 3.8.2).
WARNING
The thermal snap-switches must be
connected to a suitable earth
(ground) point.
WARNING
You must connect the thermal snap-
switches to your pump control
circuit so that the electrical supply to
the pump is switched off if either of
the thermal snap-switches open. If
you do not, the pump may overheat
and be damaged and the pump fluid
may undergo thermal breakdown.
3.8.2 Connect the boiler protection
thermal snap-switch
The thermal snap-switch protects the pump against
overheating due to a low level of pump fluid in the
boiler.
The boiler protection thermal snap-switch can be
wired in series with the cooling-fail thermal snap-
switches.
You must adust the boiler protection thermal snap-
switch when you first switch on the pump: refer to
Section 4.5.
3.9 Connect the optional Pt100
temperature probe (if fitted)
If you have ordered your 18B4B pump with the
optional Pt100 temperature probe, the pump will be
supplied with the probe fitted as shown in Figure 1,
item 30.
Connect the probe to your control or indicator
equipment as described in the manufacturer’s
instructions supplied.
WARNING
The thermal snap-switch must be
connected to a suitable earth
(ground) point.
WARNING
You must connect the thermal snap-
switch to your pump control circuit
so that the electrical supply to the
pump is switched off if the thermal
snap-switch opens. If you do not, the
pump may overheat and the pump
fluid may undergo thermal
breakdown.