The American Water Works Assn. (AWWA) announced the launch of its new ...
Proper procedures for testing to ensure meter accuracy
Solid-state water meters offer innovative, fully electronic metering technology that is designed to reduce maintenance, improve accuracy and durability and minimize water loss. With no moving parts to wear out, electronic meters provide low-flow accuracy and high-flow durability. These meters combine long-term life with dependable long-term accuracy over all flow ranges.
While electronic meters are virtually maintenance free, ongoing meter testing may be required by public utility commissions or other regulatory agencies.
In addition, meter testing is an important part of a utility’s water audit program. Water audits provide utilities with water usage information and help detect leaks in the distribution system. This enables the utility to account for the water that is actually delivered, thereby generating revenue that may otherwise be lost. Meter accuracy is an essential part of any water audit program and the best way to determine that a meter is operating accurately is to test it.
Proper procedures are critical for accurate meter testing:
Testing the Meter
These steps provide the proper procedure for testing solid-state electronic flowmeters.
1. Place the meter on the test bench. Clamp the meter securely, but do not tighten more than necessary. Verify that meter bore axes are centered within the test bench piping.
2. Run water through the system to remove any entrapped air. This purging should last roughly one minute, at or near the meter’s maximum rated flow, to ensure the system and meters have been fully purged of air.
3. Record the starting read of the meter.
4. For new meter testing, start with a high-flow test and then proceed down to the lower flows. This ensures that any minor pockets of remaining entrapped air are removed during the first few seconds of the total test sequence. The meter flow tube must be full to avoid an empty pipe condition. For meters pulled from service, the meter internals may need to be fully hydrated prior to the start of testing.
5. Open the test bench discharge valve to the desired flow rate for the maximum flow test.
6. Continue the flow at the maximum flow rate until the meter reaches the desired quantity.
7. Record the results of this test.
8. To determine the accuracy of the meter after each test, divide the consumption indicated by the meter under test by the total tank or reference meter volume.
9. If the meter is not operating within expected standards, repeat the test to verify repeatability. If the second test provides acceptable results, run the test one more time. If the second test does not produce acceptable results, consult the manufacturer’s manual or contact the technical support team.
10. Repeat steps 2 to 8 for intermediate and minimum flow tests. For the minimum flow test in particular, it is important to verify that the actual test flow rate closely matches the target flow rate.
11. When the tests are complete, remove the meter from the test bench.
Solid-state electronic water meters have become an increasingly popular option for water utilities due to their increased accuracy and reduced maintenance requirements. Should meter testing be required, following accurate testing procedures helps utilities make sound business decisions that can drive increased profitability.