AW Gear Meters GEAR METERS - Manual (Page 13)

Positive Displacement Flow Meters
Operation and Installation Manual
12
Calibrations
Each flow meter is calibrated and given a “k-factor” using a standard calibrating fluid at the factory. This
number is accurate for all fluids with most viscosities, except the most water-like. There should be no
need to change this except for fluid viscosities below 30cSt.
If flow readings are too high
If the display shows significantly more than the volume actually dispensed or shows flow when there is
definitely no flow, this most likely indicates an electrical noise problem. In such cases, turn off nearby
motors, heaters or relays, check cable shielding, and establish a clean ground independent of other
electrical devices before repeating accuracy tests. If the problem continues, it may be necessary to
relocate the offending device or reroute cabling away from noise sources.
If flow readings are too low
If the display shows significantly less than the volume actually dispensed, most likely the flow meter has
a high slippage factor, and the fluid is bypassing the gears and the k-factor may require adjustment. Dirt
or dried material can also keep gears from rotating freely.
If it is necessary to adjust the existing k-factor
Trigger at least 500ml of your sample fluid in a steady stream at approximately the desired flow rate into
a graduated beaker. Compare the volume in the beaker to the volume on the display. Do not time the
operation; merely measure the volume dispensed. Repeat the sample 3 times and take an average. If
the result is outside an acceptable margin, adjust the k-factor by the percentage of difference between
the average beaker sample and the average displayed total. If the error is not rectified, clean the flow
meter thoroughly and repeat the procedure. Do not use water for this test. For most accuracy results,
calibrate using fluid to be measured with flowmeter.
If it is necessary to re-calculate a new k-factor
You will first need a data-collecting instrument to count pulses produced by the flow meter. An AW
display may be used in totalizer mode provided the KFT is set to count each pulse (KFT = 10000). Trigger
at least 500ml of your sample fluid in a steady stream at approximately the desired flow rate into a
graduated beaker. Divide the number of pulses by the volume dispensed and the result is your new k-
factor in the units of your sample. In the example above, the k-factor units would be impulses/ml.
(photo of calibration certificate)