6-1
4220 Flow Meter
Section 6 Maintenance and Service

6.1 Routine Maintenance

and Minor Service

The following sections provide routine maintenance and ser-
vicing instructions. Included are sections on cleaning the flow
meter, reactivating the desiccators, maintaining the bubble line,
servicing the internal printer, elementary troubleshooting and
servicing CMOS circuitry.
Teledyne Isco recommends that you become familiar with the
maintenance procedures presented here. While the 4220 is rug-
gedly built to withstand severe field conditions, it will function
best and remain most reliable if you follow these simple proce-
dures.
6.1.1 Care of the Flow Meter
Case
If you close and latch the lid, and cap all the M/S connectors on
the side of the case tightly, you can clean the case by spraying it
with a hose or washing it with soapy water. Do not use a hose
with a nozzle or a high pressure hose-and-wand. Do not immerse
the flow meter in a tank of water to wash it. The flow meter can
usually withstand accidental submersion in water, if that should
occur, but it is not intended for routine submersion.
6.1.2 Care of the Case Seal From time to time you should inspect the case seal and clean it, if
necessary. The ridge around the edge of the case and the groove
on the cabinet door form a seal when the door is closed. Keep this
seal free of dirt, sand, etc. If it isn't, clean it carefully with a
damp cloth. Also keep the rubber gasket in the lid clean. You can
clean it with a small brush and a damp cloth. If you do any
cleaning while the case is open, be careful not to let any dirt or
debris fall inside the flow meter assembly. It is best to work on
the flow meter with the case standing upright. If you don't
maintain the seals properly, they may leak, causing damage and
eventual failure of the components inside.
6.1.3 Preventi ng Moisture
Damage
To prevent moisture damage to the internal components, keep
the lid tightly latched at all times, except when it is necessary to
change the program or change the chart. Do not operate the flow
meter routinely with the case open. This will expose the internal
components to dirt and moisture; it will also saturate the des-
iccant canister inside the case very quickly. Inspect this canister
periodically and recharge it as necessary as described subse-
quently. It is also important to keep the external connectors clean
by keeping the mating connectors or the protective caps tightly
screwed down. Under severe operating conditions you can spray
the threads of the connectors with a cleaner/lubricant such as Jif
or WD-40 to prevent corrosion. Be careful not to spray any of the
terminals (pins or jacks) inside the connectors; residue from the
sprays could cause intermittent or failed connections.