A gas meter is a specialized flow meter, used to measure the volume of fuel gases such as natural gas and liquefied petroleum gas. Gas meters are used at residential, commercial, and industrial buildings that consume fuel gas supplied by a gas utility. Gases are more difficult to measure than liquids, because measured volumes are highly affected by temperature and pressure. Gas meters measure a defined volume, regardless of the pressurized quantity or quality of the gas flowing through the meter. Temperature, pressure, and heating value compensation must be made to measure actual amount and value of gas moving through a meter.
Several different designs of gas meters are in common use, depending on the volumetric flow rate of gas to be measured, the range of flows anticipated, the type of gas being measured, and other factors.
Gas meters that exist in colder climates in buildings built prior to the 1970s were typically located inside the home, typically in the basement or garage. Since then, the vast majority are now placed outside though there are a few exceptions especially in older cities.
Types of gas meters
Diaphragm/bellows meters
These are the most common type of gas meter, seen in almost all residential and small commercial installations. Within the meter there are two or more chambers formed by movable diaphragms. With the gas flow directed by internal valves, the chambers alternately fill and expel gas, producing a nearly continuous flow through the meter. As the diaphragms expand and contract, levers connected to cranks convert the linear motion of the diaphragms into rotary motion of a crank shaft which serves as the primary flow element. This shaft can drive an odometer-like counter mechanism or it can produce electrical pulses for a flow computer.
Diaphragm gas meters are positive displacement meters.
Rotary meters
Rotary meters are highly machined precision instruments capable of handling higher volumes and pressures than diaphragm meters. Within the meter, two figure "8" shaped lobes, the rotors (also known as impellers or pistons), spin in precise alignment. With each turn, they move a specific quantity of gas through the meter. The operating principle is similar to that of a Roots blower. The rotational movement of the crank shaft serves as a primary flow element
Heating value
The volume of gas flow provided by a gas meter is just that, a reading of volume. Gas volume does not take into account the quality of the gas or the amount of heat available when burned. Utility customers are billed according to the heat available in the gas. The quality of the gas is measured and adjusted for in each billing cycle. This is known by several names as the calorific value, heating value, or therm value.
The calorific value of natural gas can be obtained using a process gas chromatograph, which measures the amount of each constituent of the gas, namely:
Additionally, to convert from volume to thermal energy, the pressure and temperature of the gas must be taken into consideration. Pressure is generally not a problem; the meter is simply installed immediately downstream of a pressure regulator and is calibrated to read accurately at that pressure. Pressure compensation then occurs in the utility's billing system. Varying temperature cannot be handled as easily, but some meters are designed with built-in temperature compensation to keep them reasonably accurate over their designed temperature range. Others are corrected for temperature electronically.
- methane
- ethane
- hydrogen
- carbon monoxide
Indicating devices
Any type of gas meter can be obtained with a wide variety of indicators. The most common are indicators that use multiple clock hands (pointer style) or digital readouts similar to an odometer, but remote readouts of various types are also becoming popular — see Automatic meter reading and Smart meter.
Accuracy
Gas meters are required to register the volume of gas consumed within an acceptable degree of accuracy. Any significant error in the registered volume can represent a loss to the gas supplier, or the consumer being overbilled. The accuracy is generally laid down in statute for the location in which the meter is installed. Statutory provisions should also specify a procedure to be followed should the accuracy be disputed. In the UK, the permitted error for a gas meter manufactured prior to the European Measuring Instruments Directive[3] is ±2%.[4] However, the European Measuring Instrument Directive has harmonised gas meter errors across Europe and consequently meters manufactured since the directive came into force must read within ±3%. Meters whose accuracy is disputed by the customer have to be removed for testing by an approved meter examiner.[5] If the meter is found to be reading outside of the prescribed limits, the supplier has to refund the consumer for gas incorrectly measured while that consumer had that meter (but not vice versa). Any refund is limited to the previous six years.[6] If the meter cannot be tested or its reading is unreliable, the consumer and supplier have to negotiate a settlement. If the meter is found to be reading within limits, the consumer has to pay the costs of testing (and pay any outstanding charges).
Gas meter smart metering technologies and usage
Smart metering technologies for gas meters refer to advanced systems that enable real-time monitoring, data collection, and analysis of water usage through digital and connected devices. Unlike traditional mechanical gas meters, smart meters are equipped with electronic components that measure water flow and transmit the data wirelessly to utilities and consumers. Smart water meters are integrated with Internet of Things (IoT) platforms, allowing for more efficient gas management and improved customer engagement.
RF Technologies and Protocols
Radio Frequency (RF) technologies form the backbone of smart metering systems by enabling wireless communication between meters and utility networks. Several RF technologies and protocols are widely used in smart gas meter:
- Wireless M-Bus (WMBus): WMBus, compliant with the European EN 13757 standard, is widely adopted across Europe for water, gas, and electricity metering. It offers secure, reliable, and energy-efficient communication tailored for utility applications.
- Wize technology: A protocol based on the 169 MHz frequency band, WIZE is designed for long-range, low-power communication. It is commonly used in Europe for water and gas metering due to its excellent signal penetration and scalability.
- LoRaWAN: LoRaWAN is valued for its long-range and low-power capabilities, making it suitable for large-scale deployments in both rural and urban settings. It is widely used in industrial and municipal applications.
Flow measurement calculations
Turbine, rotary, and diaphragm meters can be compensated using a calculation specified in American Gas Association Report No. 7. This standardised calculation compensates the quantity of volume as measured to quantity of volume at a set of base conditions. The AGA 7 calculation itself is a simple ratio and is, in essence, a density correction approach to translating the volume or rate of gas at flowing conditions to a volume or rate at base conditions.
Orifice meters are a very commonly used type of meter, and because of their widespread use, the characteristics of gas flow through an orifice meter have been closely studied. American Gas Association Report No. 3 deals with a broad range of issues relating to orifice metering of natural gas, and it specifies an algorithm for calculating natural gas flow rates based on the differential pressure, static pressure, and temperature of a gas with a known composition.
These calculations depend in part on the ideal gas law and also require a gas compressibility calculation in order to account for the fact that real gases are not ideal. A very commonly used compressibility calculation is American Gas Association Report No. 8, detail characterization.
Thread Sizing Standards and Dimensions
Thread sizing standards
Residential, commercial and industrial gas meters have their own standard thread sizes. The gas meter is connected to customer piping through a swivel and nut, which has a dedicated set of thread sizes.[9] Threads are helical structures used on screws, bolts, pipes, and other fasteners to facilitate the joining of components. Their design and standardization vary depending on their intended application, material, and region.
Standardized Thread Systems Several organizations and systems have established standards for threads to ensure interchangeability and reliability:
- ISO Metric Thread (M)
- The most widely used thread standard internationally.
- Specified by the International Organization for Standardization (ISO).[10]
- Threads are defined by their nominal diameter and pitch (distance between threads) in millimeters. For example, an M10x1.5 thread has a nominal diameter of 10 mm and a pitch of 1.5 mm.
Main Suppliers
The top ten depends on the ranking methods,[13][14]
- Honeywell
- Sagemcom
- Itron
- Apator
- Landis+Gyr
- Xylem (formerly Sensus)
See also
- Automatic Meter Reading
- Flow conditioning#Effects on flow measurement devices
- Electricity meter
- Flow measurement
- Gas flow computer
- Gas meter prover
- Meter-Bus
- Julius Pintsch
- Smart meter
- Thermal mass flow meter
- Turnaround document (way of collecting data from)
- Utility submeter
- Water meter
References
- American Gas Association Transmission Measurement Committee (2007). AGA Report No. 9: Measurement of gas by multipath ultrasonic meters (2 ed.). Washington, DC: American Gas Association.^
- Myer Kutz. Handbook of Measurement in Science and Engineering Wiley, 2016^
- European directive (2004/22/EC)^
- the Gas (Meters) Regulations 1983