AW Gear Meters GEAR METERS - Manual (Page 11)

Positive Displacement Flow Meters
Operation and Installation Manual
10
Maintenance
Follow these general guidelines for operating and maintaining your positive displacement flow meter.
Use the Maintenance Guides
Always review the Maintenance Guides provided with the flow meter (download additional copies at
www.awgearmeters.com ) prior to attempting any maintenance work. The majority of down time and
repairs is the result of breakages due to improper maintenance actions, lack of training or rough
handling.
Flow Testing
Do not use water for flow testing. The viscosity of water is too low to produce accurate results unless
the flow rate is elevated, and the internals would then have to be dried and lubricated to avoid
corrosion or scaling. If system calibration is necessary, the preferred calibration fluid is the actual fluid to
be metered. Alternatively, using a fluid with a viscosity of approximately 30 cSt

such as mineral oil or
thinned glycerin is recommended.
Plugging and Filtration
Filtration is recommended to prevent contaminants from entering the flow meter. Should the flow
meter become plugged, a reduced flow may still be observed from the outlet as fluid pressure will
squeeze fluid through the flow meter – visual flow does not necessarily mean that the flow meter’s
gears are turning. If contaminants are causing the plugging, install filtering. If particle buildup repeatedly
causes plugging, review the cleaning and maintenance procedures in the Regular Cleaning section on
page 8. Because of the considerable differences in fluid types and in-plant procedures, some trial and
error may be required to determine the ideal flushing or cleaning regimen.
Calibration
A calibration factor (k-factor) is established at the factory on a preferred calibrating fluid. This number,
which is provided with the flow meter either on a Calibration Data Sheet or on a tag attached to the flow
meter, is usually accurate for a wide variety of fluids and should not usually be changed. Should the data
sheet become lost, contact the factory for a duplicate copy. See the Calibrations section on page 12 for a
calibration verification procedure.
Storage
When the flow meter is idle or stored for any extended period, perform the following:
1. Clean the internals thoroughly with the appropriate fluid
2. Lubricate with a light oil or other non-corrosive fluid
3. Cap or plug the ports to prevent drying
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cSt is a unit of kinematic viscosity that equals one hundredth of a stoke