Utility meters are used to monitor the consumption of water, gas or electricity by businesses or residences. They differ in terms of measurement technology and user interface. Utility meters with a standard register have a graduated dial and visible gears or wheels. They are driven by a magnetic coupling between a magnet in the measuring chamber and a magnet at the bottom of the register. Many registers include a leak detector, a small disk or hand that is geared closely to the rotational speed of the drive magnet. Utility meters with digital readouts are also available. Electric meters are utility meters that measure the amount of electricity supplied to a building, factory, or facility.
Types of Utility Meters
There are several basic types of products: usage meters, demand meters, and variable rate meters. Usage meters use electromechanical induction to count the revolutions of a metallic disc which rotates at a speed proportional to the amount of energy used. Electricity usage is measured in watts-hours (Wh) , kilowatt-hours (kWh), joules (J), or mega-joules (MJ). Demand meters measure the temperature of a conductor to identify average and maximum demand. These devices have an analog front panel with a pointer, usually a needle, which moves a marker. After a demand meter is read, an operator resets its value with a magnet. Variable rate utility meters or multiple tariff meters allow utilities to charge customers different rates (tariffs) at different times of day. Time-of-use (TOU) meters have a time switch, multiple registers, and two rates: on-peak and off-peak. Gas meters are utility meters that measure the flow of fuels such as natural gas, methane, and propane.
There are four basic types of products: diaphragm or bellows meters, rotary meters, turbine meters, and clamp-on meters. Diaphragm meters or bellows meters consist of two chambers that expand and contract with the filing and emptying of gas loads. Rotary meters are positive displacement (PD) gas meters that use a blower instead of a pair of diaphragms or bellows. Turbine gas meters are less accurate than PD meters, but provide the greatest gas flow. Clamp-on meters use time of flight (TOF) and cross-correlation techniques to measure the flow of gas in any size of pipe. Natural gas is commonly measured by the cubic foot and billed by the thousands of cubic feet (MCF) or hundreds of cubic feet (CCF). Water meters are utility meters that are used to measure water usage in gallons, cubic feet or cubic meters. They measure flow with displacement, velocity, or electromagnetic methods and include product types such as single-jet meters, multi-jet meters, fire meters, fire hydrant meters, electromagnetic meters, and compound meters. Displacement water meters contain an oscillating piston or nutating disc and movable measuring element. Velocity water meters measure the velocity of flow though a known internal capacity. Sub-types include multi-jet, turbine, fire, fire hydrant, and compound meters. Electromagnetic or mag meters also measure the velocity of water flow, but with electromechanical means instead of mechanical methods.