Gas metering devices are critical for controlling or measuring the flow of gases in pipes in a wide range of applications across the residential (utilities), commercial, and industrial sectors. Depending on the application type and required level of accuracy, you may have to choose from different types of gas metering devices, including traditional gas meters or newer technologies.
Link to TNMA
Read on for an overview of the various types of gas metering devices. Equipped with this information, you will be able to make the best choices for your applications.
Each natural gas meter has its own benefits and limitations and excels in different types of applications. While the external appearance of most gas meters may be quite alike, they work on different types of mechanisms:
Note that most types of gas meters may come with the option of analog displays or digital indicators.
An excellent fit in residential gas billing, diaphragm gas meters are Positive Displacement (PD) gas meters that measure the volume of gas by displacing components within the meter. In addition to being reliable, low-cost, and long-lasting, they offer the best turndown ratios in the industry (~80:1), making diaphragm gas meters ideal for metering pilot gas, as well as custody transfer of natural gas. Diaphragm meters work best with low-pressure systems of 0-100 PSI with low flow rates.
Learn more about diaphragm gas meter.
Another type of PD gas meter, rotary gas meters are precision instruments with one of the highest accuracy rates in the industry. They measure the flow of gas through the number of rotations of the rotors (rotors let gas through only when they turn). Their ability to handle higher volumes and pressures than the diaphragm gas meters (up to ~175 PSI) makes them suitable for a range of low to high capacity industrial and commercial applications. They offer a turndown ratio between ~10:1 to ~80:1 depending on the make and the application.
Learn more about rotary gas meters.
Using a small helix or turbine to determine the speed at which the gas is moving through the turbine, turbine flow meters deduce the flow of gas on a volumetric basis. They primarily find application in the chemicals and oil industries. They are most suited for applications that require highly accurate measurements and are also approved for custody transfer of natural gas. Typically, most turbine meters can handle high-pressure systems (as high as PSI) with high flow rates and provide a turndown ratio of ~10:1.
Learn more about turbine flow meters.
A type of differential pressure meter, orifice meters infer the rate of gas flow by measuring the pressure drop over an obstruction inserted in the flow. Besides their use in custody transfer of natural gas, orifice gas meters are the most popular method of flow measurement for industrial applications as they have no moving parts and are easy to field service. Orifice plate meters offer a practical turndown ratio of 3:1.
Used in the process industries for monitoring gas at plants or in labs or filtration loading, rotameters do not need any external power, making them a great fit in hazardous locations with flammable gases. Rotamers offer an extended measurement range with reasonable accuracy in low and medium rates. Additionally, they are inexpensive and highly resistant to chemical action, as well as thermal shock.
Measuring the mass of gas flowing through the meter by a physical principle called the Coriolis effect, Coriolis gas meters can handle a wide range of flow rates and have the highest accuracy of mass flow measurement.
Also known as immersible mass flow meters or thermal dispersion meters, thermal mass flow meters comprise a set of instruments that measure the total mass flow rate for gases through the heat convection from heated surfaces to the flowing gas. They excel at many applications, including energy management, natural gas, biogas, flare gas, airflow and combustion control, and offer a turndown ratio of ~:1.
A type of velocity-flow gas meter, ultrasonic gas meters use ultrasound to measure the speed of gas inside the pipes. One of the largest applications is in the custody transfer of natural gas, where they are used throughout the network in gathering, transmission, as well as distribution. They excel in measuring the flow of steam and gases, and most ultrasonic meters have a turndown ratio of 50:1.
Source: Honeywell Smart Energy
Vortex meters operate under the vortex shedding principle and measure volumetric gas flow. They are ideal for accurately measuring compressed air or steam. Since they have no moving parts, they offer high reliability and stability and do not need costly maintenance or repairs. Vortex meters are popular tools for metering, measurement, and control of gas or steam processes in power or energy facilities, as well as heavy industrial applications.
Achieving accurate gas measurement or metering is a top priority for many industrial, commercial, and residential applications. However, despite the wide choice in types of gas meters, no meter technology is perfect. In order to make the right choice for your applications, consider the following:
Norgas Controls specializes in the regulation and measurement of natural gas across Canada. We carry different types of natural gas meters including diaphragm, rotary, and turbine flow meters as well as other products dedicated to the gas industry such as gas regulators and valves. Our products are primarily used in submetering, utilities, commercial and industrial applications and we can help you find the right solution for your application.
Contact us to discuss your requirements of Gas Meter Test Bench. Our experienced sales team can help you identify the options that best suit your needs.
This post delves deeper into grouping natural gas meters using the flow mechanisms, creating seven distinct types of meters.
Empower your decision-making process by better understanding natural gas flow meters better. Some meters are approved for custody transfer, while others excel in various industrial applications. Some measure mass flow, while others are volumetric and require peripheral equipment to derive the flow rate. By grasping these nuances, you can make informed choices that align with your specific needs and goals, as each meter has its own benefits and excels in different applications.
Additionally, we encourage you to look at our infographics, which cluster the meters in new and interesting ways. Download it now.
Request a Quote
Differential pressure meters are approved for custody transfer applications. They measure volumetric flow rates and are a traditional technology. Different differential pressure meters are orifice plates, pitot, and Venturi tubes.
An orifice meter is a differential pressure meter that infers the flow by measuring the pressure drop over an obstruction inserted in the flow. As the turbine meter, the orifice plate is an inferential meter, as it infers the volumetric flow rate by measuring a property of the flow stream. Along with custody transfer, orifice meters are a commonly accepted method of flow measurement for industrial applications; they have no moving parts and are easy to service. Unfortunately, they have limited turndown and do not handle a wide range of flow rates. They also have reduced low-flow sensitivity and require gas static pressure, differential pressure, viscosity, density, and temperature to measure gas flow accurately.
Coriolis meters&#; principle of operation is based on motion mechanics. The meter provides a direct mass flow measurement based on the fluid&#;s deflection force moving through a vibrating tube. They are a custody transfer meter, considered new technology, very accurate with high turndown capabilities, and independent of fluid properties. They are also costly to install and unsuitable for larger pipe sizes.
Positive displacement meters are direct measurement meters and are considered a traditional technology. They operate on the volumetric flow principle by sectioning the gas flow into specific segments that fill and empty (displace) as the meter revolves. Each revolution is associated with a particular volume, and the meter reads in cubic feet (or cubic meters). Positive displacement meters have sufficient accuracy and high turndown. However, they have moving parts, so wet and dirty gas are problematic when using them.
Diaphragm meters are residential gas meters for commercial and light industrial applications. They are approved as a custody transfer meter. The gas or fluid flows into the meter inlet with an oscillating diaphragm. The compartment fills and displaces to the outlet; each diaphragm revolution determines the flow rate.
The rotary meter is for higher volume or pressure use for commercial or industrial applications. They are also custody transfer meters. For this meter type, the gas or fluid flow is divided by a rotating impeller or rotor, which has vanes, and each rotation determines the flow rate.
Thermal dispersion is a new technology.
A thermal mass flow meter is an instrument that directly measures gas mass flow in many industrial applications to improve process efficiency and conserve energy. They are also used to monitor methane emissions and report greenhouse gases. The meters have a wide turndown, excellent repeatability, and no moving parts. They have a low-pressure loss and can withstand high temperatures but require a long straight run. There is no need for ancillary pressure and temperature equipment.
A variable area flow meter is a traditional gas technology meter consisting of a tube and float. The float response to flow rate changes is linear with a 10-to-1 flow range or turndown.
The rotameter is an industrial flow meter that measures the volumetric flow rate of gases and liquids in a closed tube. It is a variable area meter and provides a simple and inexpensive indication of flow rates. It has fair accuracy.
The turbine gas meter is considered a traditional technology and measures the volumetric flow rate, which is calculated based on a rotor&#;s angular velocity in the meter. It is a custody transfer meter with high accuracy but requires pressure and temperature compensation. It also has moving parts, so the user must consider gas cleanliness. This meter type is limited to measuring low flow rates and has a high-pressure loss.
The ultrasonic meter indirectly measures mass flow. Ultrasonic flowmeters measure the difference in pulse transit time that travels from a downstream transducer to the upstream transducer compared to the upstream sensor back to the downstream transducer. The meters are usually used at pipeline meter stations in high-flow and high-pressure applications where the slightest inaccuracy can negatively impact the bottom line. This meter style is exceptionally accurate, has a high turndown ratio, and has excellent rangeability, but it is costly.
Vortex meters are latecomers to API approval for custody transfer of natural gas. This late approval has made it difficult for the meter to catch up to other custody transfer meters (Coriolis, diaphragm, rotary, turbine, ultrasonic). Consequently, vortex meters are primarily used in industrial markets with very little custody transfer of natural gas usage. The meters measure volumetric gas flow; they have good rangeability but are costly.
A Virtual flow meter (VFM) is a mathematical tool that estimates flow rates without physical hardware using data-driven algorithms powered by artificial intelligence. This innovative approach is particularly beneficial in scenarios where installing meters is challenging.
Are you interested in learning more about Gas Meter Water Leakage Test Bench? Contact us today to secure an expert consultation!