Page 90 - Water Loss Control

72 Cha pte r S i x

In order to calculate an adjustment to account for meter inaccuracy (see Table 6.6)
divide the uncorrected metered volume (UMV) by the measured accuracy of the meter
(a percentage expressed as a decimal) and subtract the UMV as follows:
Uncorrected metered volume
− uncorrected metered volume
Percent accuracy
= meter error
Then calculate the adjusted metered volume (AMV) as:
Adjusted metered volume = uncorrected metered volume ± meter error

A checklist of activities is given in Table 6.7. Some source meters (8, 10, 12 in diam-
eter) fall within the same size range as large customer meters. Because of this, operators
with source meters in this size range can also refer to Chap. 12 for further information
on accuracy testing of these meters. While many reliable meter types and brands pro-
vide excellent service for many years, water utilities should make a particular effort to

Pre-test Activities
1 Identify and locate all meters
2 Reference all available manufacturer’s specifications for those meters
3 Confirm the meter installation according to the manufacturer’s specification
4 Determine whether onsite testing can be undertaken
5 Identify the type of onsite testing to be undertaken and its realistic limitations
6 Define an allowable band of error between the test volume and metered volume
7 Locate any records of prior testing or repair work and factor this information into
the planning of the test
8 Identify a local supplier or contractor who can calibrate the meters which fall
outside the allowable limits
9 Research manufacturers and suppliers for replacement meters for those meters
which cannot be calibrated
10 Set a realistic budget for the work
11 Establish a realistic time frame for the work to be carried out
12 Identify an accountable tracking mechanism to clearly show both a baseline
measurement before calibration and a calibrated measurement after testing
Post-test Activities
Clearly identify and record any major changes in calibration, both for span and zero
Identify the impact on the annual water balance
Store both raw and adjusted data for future reference
Identify local extraction limitations and how they are affected by the new results
Put in place a periodic testing program to ensure that the meters stay calibrated
and the new results accountable
TABLE 6.7 Source Accuracy Testing Checklist of Activities