Teledyne 4220 - Manual (Page 84)

4220 Flow Meter
Section 3 Installation
3-2
cartridge should be colored blue. If it is violet or pinkish, you
need to regenerate it. You will need to remove the particles from
the cartridge for regeneration; you cannot regenerate the car-
tridge like the case desiccant canister. The cartridge is plastic
and will melt. See Section 6 for details on regenerating the des-
iccant cartridge.
CAUTION
Do not operate the flow meter with the door open or the desic-
cators saturated. If you leave the door open, moisture in the air
will quickly saturate the desiccant canister and begin to attack
electronic components. Dust may damage the internal plotter.
Water or dirt drawn into the reference port can block the tub-
ing, preventing the pressure transducer from referencing to
atmospheric pressure.
Many flow meters are installed in damp environments. where
the air often carries corrosive fumes. Moisture combined with
these fumes can form acids. These acids can corrode printed
circuit boards, resulting in unreliable operation and eventual
failure of the unit. If the damage is extensive, it can completely
ruin the flow meter. Keep the lid closed and latched except when
you are installing the unit or changing the program.
Symptoms of a clogged reference port on the submerged probe
are varied. Noticeable drift in measured level when you know the
level is essentially constant, or an oscillation in the level corre-
sponding to changes in barometric pressure are two indicators of
clogging in the reference port tube.
If dirt and/or moisture block the reference tube between the des-
iccant cartridge and the Submerged Probe connector on the flow
meter, you may be able to clear the blockage from the tube by
applying compressed air. Likewise, if the blockage is inside an
extension cable for the submerged probe, you can try to clear it
with air. In these cases, both ends of the tube are accessible.
However, if the blockage is inside the submerged probe's cable,
the probe will have to be returned to the factory for evaluation.
In some cases, Teledyne Isco’s service department can vacuum
moisture from the reference line. However, if the blockage cannot
be vacuumed out, or if moisture remains inside the probe for a
prolonged period, the probe will be ruined beyond repair. You
cannot reach the end of the tube attached to the pressure trans-
ducer. The cable is sealed where it enters the submerged probe
and the probe itself is a sealed unit. Consequently, you cannot
push air through the tube. Applying pressure to the connector
end of the cable will only drive the plug further into the line, and
will likely ruin the transducer.
You can avoid this problem completely simply by preventing sub-
mersion of the reference tube inlet and maintaining the desic-
cators. Inspect them frequently and regenerate them when
necessary.