meter is out of tolerance by more than .0025, then it must be adjusted or
taken out of service. If this cannot be done, then you may use the meter
factor or meter percent error to adjust the meters registered reading on
the gallons pumped. The instructions for adjusting the meter are
normally placed inside the top cover or in the manufacturer's manual.
Preparation.
Meters must be checked under normal operating pressure and flow rate.
The prover must have the capacity for no less than the volume
delivered through the meter in one minute.
Fill the prover and then empty to the zero mark (dry run). This
removes air pockets in the line and warms up the meter.
During the dry run, the time and flow rate can be determined.
All gages and thermometers will be checked for accuracy.
All fittings and valves must be checked for leaks.
Verification Records and Reports.
Meter test results. The following information will need to be
included on all meter verification reports and records in order to obtain
reliable meter performance rating:
Closing meter reading, after the prover is full.
Opening meter reading; this is for meters that cannot be set to zero.
Registration; quantity recorded by the meter.
Example:
* Closing meter reading = 2,762
* Opening meter reading = 1,920
* Quantity Recorded = 2,762 - 1,920 = 842 gallons
Temperature of metered stream.
Temperature correction factor.
Registration corrected to 60 degrees Fahrenheit equals amount pumped
times the correction factor.
Elapsed time. Elapsed time for test in seconds. (It will usually
take less than a minute to fill the prover.) Elapsed time for test in
minutes. (The flow rate is in GPM, so seconds must be corrected to
minutes.)
Rate of flow. The total register reading corrected to 60 degrees
Fahrenheit divided by the elapsed time for the test equals the rate of
flow. (This tells you whether the meter is running at its prescribed
flow rate in one minute.)
Closing prover tank reading (percent). The prover is allowed to be in
excess of the rated capacity by +1percent or -1percent. (The
graduations are in 10ths.) If the prover is rated at 840 gallons and
the closing percent is +2, then change the percent to a decimal (for
example 2percent is changed to .002); multiply the prover capacity
(840) by .002 = 1.68 gallons. (Note: You pumped 841.68 gallons).
Closing prover tank readings (gallons). 841.68 gallons.
Opening prover tank reading is always 0.
Delivery. The closing prover tank reading minus the opening reading
equals the delivered amount.
Prover temperature. If the prover has an upper and lower thermometer
this would be the average of the two.
12-128
QM 5099
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