Page 86 - Water Loss Control

68 Cha pte r S i x

and creating spreadsheets or databases that properly balance flows such that an accurate
value of water supplied is attained and made available to the water audit each year.

6.3 Types of Source Meters
Source meters come in a wide variety of types, sizes, and flow-registering mechanisms.
Some of the more common types include
Differential pressure meters
Venturi meters
Dall tube meters
Orifice plate meters
Proportional flowmeters
Magnetic meters
Insertion meters
Ultrasonic meters
Turbine meters
Propeller meters
Vortex shedding meters

All types have advantages and disadvantages in any given application and each
metering site must be evaluated independently to determine the optimum meter. It is
important that an established meter function according to its specification and the data
being recorded are compatible with the other source meter data being collected through-
out the water utility. Detailed guidance on source meter types, function and manage-
2
ment is provided in the AWWA M33 publication Flowmeters in Water Supply . Figures 6.2
through 6.5 show a sequence of photos from the replacement of a large magnetic flow-
meter on a raw (untreated) water supply main in Philadelphia.

FIGURE 6.2 Source meter replacement at raw water pumping station: Existing meter removed
and placed next to new 48-in diameter magnetic meter prior to its installation. (Source:
Philadelphia Water Department.)