Water Well Journal
Issue link: https://read.dmtmag.com/i/643500
net in the measuring chamber attached to the impeller assembly and another magnet attached to the bottom of the register assembly. A relatively new addition to this line of meters uses a radio transmitter to en- able reading the meter from a remote distance. The meter is designed to trans- mit an encoded or pulse electronic out- put to a remote reading device—and is often referred to as an automated meter reading or AMR style. The meter is pro- vided with a built-in battery to power the radio. Since the meter is read only monthly or every two months, the battery can last for many years, and conceivably the life of the meter. Both of these meter types are also ca- pable of registering low flows, down to 0.25 GPM. This is a critical distinction from other types of flowmeters since this rate is often seen in trickling flow applications during freezing conditions to prevent the freezing of water pipes— and this flow may not be read by other styles. Turbine Meters The next style of flow measuring de- vice is the turbine style. Turbine meters are less accurate than displacement and multi-jet meters at the low flow rates often associated with residential set- tings, but the measuring element does not occupy or severely restrict the entire flow path. The flow direction is typically straight through the meter body, provid- ing for higher flow rates at a resultant lower pressure drop than a comparable displacement type of meter. The turbine meter is often chosen for larger com- mercial applications, fire protection, and as master meters for water distribution systems. They are also frequently used as flowmeters for lower volume well or booster pump reads since other types may not be practical or accurate. Turbine meters are usually available in connection sizes from 1.25 inches up to 12 inches and are usually constructed from bronze, cast iron, or ductile iron materials. Turbine meters are often joined with PD or multi-jet meters to create a com- pound meter assembly. The meters are connected in parallel to allow low flows to be read by the smaller meter and the larger flows read by the turbine meter. This type of assembly is often used for large commercial or industrial applica- tions where the range of flow during a typical day can be quite large. A primary advantage of the turbine meter is it is not as affected by upstream or downstream piping as other types of metering devices. As a result the turbine meter can be connected directly to wells, pumps, and to other flow-modifying fittings. Propeller Meters The next method of flow measuring devices is the propeller meter (Figure 3, shown with straightening vanes and reg- ister head). The propeller meter is a typ- ical flow measuring method commonly used with monitoring the instantaneous flow output of well and booster pumps and the totalization of that flow. Propeller meters are popular in mu- nicipal, agricultural, commercial, and industrial applications for measurement of a wide range of water flows and are typically 98% or more accurate when operating within their allowable flow range. Propeller meters use an interior pro- peller rotating as the flow passes over it, causing it to spin. The action is similar, although the reverse, to the action of a prop pushing a boat through the water. Propeller meters are available in pipe sizes ranging from 2 inches to more than 48 inches, although the most com- mon sizes range from 4 to 12 inches. The meters are typically accurate when applied in the proper format and when operated within the desired flow range. ENGINEERING continues on page 60 Twitter @WaterWellJournl WWJ March 2016 59 Figure 1. A typical residential water meter. Figure 2. A typical water meter register showing a meter reading of 8.3 gallons. Notice the black "1"on the odometer has not yet fully turned over, so only the red hand is read. Figure 3. A propeller meter.