Dewpoint Temperature
The temperature to which the gas must be cooled in order that it should be
saturated with water vapour (i.e. 100% relative humidity). For practical reasons it
is referred to dewpoint above 0 °C and frostpoint below 0 °C.
Parts Per Million by Volume
ppm(v) is the ratio of the water vapour pressure to the total gas pressure.
Parts Per Million by Weight
ppm(w) is the ratio of the molecular weight of water vapour to the molecular
weight of the carrier gas mixture.
11.6 Problem Guide
33
Fault
Explanation
Required Action
Notes
Unit does not turn on.
Screen remains blank
and back light off.
Battery low level.
Connect a battery
charger unit for
a minimum of 12
hours charging.
AutoCal failure.
Sensor sensitivity
too low.
Repeat AutoCal.
If AutoCal fails,
contact supplier
to replace sensor.
Unit always reads
lower limit.
Sensor cable
broken.
Repair cable.
Unit will not dry down
to lower limit.
Sieve wet.
Perform service on
unit using Service
Kit.
Service Kit
available from
supplier.
‘O’ ring failure.
Perform service on
unit using Service
Kit.
Service Kit
available from
supplier.
Battery has short life
between charges.
Battery reaching
end of life.
Return to supplier/
authorised
distributor
for battery
replacement/
exchange.
Order from
supplier.
Keypad damaged.
Check function
of keypad
electrically.
Contact supplier.
