national multiple family submetering and allocation billing program ...

The ASME submeter accuracy standard for meters with flows between .25 gpm and 15
gpm is +/- 1.5% at their normal flow range. For these same meters, the accuracy range for their
minimum normal flow is +1% and –5%. Under the ASME standard, meters can be tested at
flows down to 0.1 gpm for an accuracy range of +1% to –5%.
Point of Use Meter Issues
The AWWA meter standards (C700) apply to cold-water meters that are tested at flow
rates from .25 gpm to the meters capacity, up to 160 gpm. The NSF/ANSI 61-2001, which is
C700 by reference, applies to water meters installed downstream of water utility master meters in
flow ranges under 15 gpm for cold and hot water use. However, both these standards address the
product and not operation and maintenance standards. Certification tests for these standards are
conducted with the meter in generally one orientation, with straight pipes entering and exiting
the meter. In practice, however, many submeters and POU meters, in particular, are often
subjected to a much wider variety of conditions. Thus, installation standards are needed along
with the manufacturer’s installation specifications. In addition, the industry needs to agree upon
acceptable accuracy standards for POU meters under adverse application conditions not just for
the meter under ideal conditions (straight pipe, cold water, and one orientation, etc).
The ad hoc committee discussed what was believed to be the important issues that needed
to be addressed in application standards for POU meters. These issues included low battery data
transmission and battery life, application accuracy; meter read (consumption) verification,
labeling and identification, and maintenance. These issues are discussed below. The committee
believes that other issues, such as data transmission, product durability, and testing protocol are
already addressed in the various codes.
Battery life
Committee member comments:
- Battery durability within the submeter standard should reference the Underwriters
Laboratories standards. Influence factors such as voltage, heat, vibration, etc. are well
covered in International Officials for Legal Metrology (OIML) water meter standards.
- The owner, manager, and/or apartment dweller should be notified in advance of the
expected battery life.
- When the battery fails, the meter reading should stop, thus notifying (by default) the
owner, manager, or other interested party.
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