FEATURES
47
Municipal
water meter.
Types of metering devices
Does a water bill indicate an abnormal water consumption? The amount
might not be pleasant for your customer to pay, but without it, one would
not know that a pipe is leaking.
By Rory Macnamara
There are two common approaches to flow
measurement: displacement and velocity, each
making use of a variety of technologies. Common
displacement designs include oscillating piston and
nutating disc meters. Velocity-based designs include
single- and multi-jet meters and turbine meters.
There are also non-mechanical designs, for example
electromagnetic and ultrasonic meters, and meters
designed for special uses. Most meters in a typical water
distribution system are designed to measure cold potable
water only. Speciality hot water meters are designed
with materials that can withstand higher temperatures.
Meters for reclaimed water have special lavender
register covers to signify that the water should not be
used for drinking.
Additionally, there are electromechanical meters, like
prepaid water meters and automatic water reading
meters. The latter integrates an electronic measurement
component and an LCD with a mechanical water meter.
Mechanical water meters normally use a reed switch,
hall or photoelectric coding register as the signal output.
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After processing by the microcontroller unit (MCU) in the
electronic module, the data is transmitted to the LCD or
output to an information management system.
Water meters are generally owned, read, and maintained
by a public water provider, such as a city, rural water
association, or private water company. In some cases, an
owner of an apartment complex or commercial building
may be billed by a utility based on the reading of one
meter, with the costs shared among the tenants based
on some sort of key (size of flat, number of inhabitants)
or by separately tracking the water consumption of each
unit in what is called sub-metering.
Displacement water meters
This type of water meter is most often used in residential
and small commercial applications as well as homes.
Displacement meters are commonly referred to as
positive displacement (PD) meters. Two common types
are oscillating piston meters and nutating disk meters.
Either method relies on the water to physically displace
the moving measuring element in direct proportion to
the amount of water that passes through the meter. The
Continued on page 48 >>
June 2017 Volume 23 I Number 4