IM-P402-139
AB Issue 1
11
6. Maintenance
CAUTION: Suitable anti-static precautions
must be observed during any maintenance procedure.
Probe body cleaning instructions - Use a cloth dampened with tap / de-ionised water or
isopropyl alcohol. Use of other cleaning materials could damage the product and invalidate
the warranty.
Boiler water level controls - Require regular testing and inspection. For specific testing
instructions for Spirax Sarco systems please see separate literature.
100% = 20 mA
Absolute maximum safe
water level
Set point 50%
0% = 4 mA
Absolute minimum water
level (water must always
be visible in glass)
High alarm 85%
Control band 20%
(symmetrical about the
set point)
Low alarm 20%
60%
40%
Warning:
If the product detects a fault, the light will flash red once a second and the output
will transmit a low level signal. See Section 8, Technical Data, Alarm state and Section 7
Fault finding. Ensure the controlling product is configured to shut the system down safely.
Fig. 5
Summary of Contents for PA420
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