Gas flow meters are used to measure the volume of gases that flow through any given system. They are widely used across commercial, industrial, and residential settings to measure and keep track of the amount of gas flowing through the system. As different gas systems have varying designs, use different gases and flow rates, and can be affected differently by variables such as heat and pressure, several different types of gas flow meters are commonly used to measure gas flow.
Diaphragm / bellow meters
By far the most common type of gas flow meter is the diaphragm or bellow meter. These meters can be found in practically all residential homes and many other smaller commercial settings. The bellow meter works by having movable diaphragms that form two or more chambers. Valves inside the meter direct the gas flow causing the chambers to alternately be filled and emptied of gas. This motion produces a practically continuous and easily measurable flow of gas through the meter. The diaphragms movement causes a set of cranks, or gears, to be set in motion. These gears are connected to a counter which can count each time the gas fills and empties the chambers, providing a measurement of gas consumption.
Turbine gas flow meters work by measuring the velocity of the gas that flows through the meter. The flow rate can be used to determine the flow rate of the gas. Turbine meters are usually used in industrial settings where gas flow is relatively good and consistent. However, as they are quite small, they are sometimes used to measure gas flow to furnaces and boilers. The velocity of the gas is measured by a small turbine, which then records the flow mechanically and relays the information to a counter. Turbine meters work well where gas flow needs to remain fairly constant, as they don’t disrupt the flow of gas.
Rotary meters are designed to deal with very high pressures and volumes of gas flow. They are typically used in more commercial and industrial settings where high pressured and high volume gas flow is needed, such as in industrial pipelines. Rotary meters have to be carefully designed and engineered to be precision measuring instruments. Inside the meter, two pistons can be found spinning in alignment. Each spin, or rotation, of these pistons causes a set amount of gas to be transferred. A crank shaft connected to the pistons and a counter then keeps a track of all the gas that flow through the meter.
The ultrasonic gas flow meter uses sound waves to measure the velocity and the flow of gas. A computer measures the time it takes for sound waves to travel between two points in a gas system. The sound waves are beamed in each direction and the difference in time that it takes to travel between the two points can be used to determine the velocity of the gas. However, as other variables can affect gas flow, the computer in the meter needs to take any external variables into account before an accurate measurement can be given. Ultrasonic meters are typically used in large commercial and industrial settings.
Coriolis meters are complex mass flow meters than can measure the flow of a range of substances. As many products are often sold by weight instead of volume, the ability of Coriolis meters to measure mass flow as well as volumetric flow has seen a wide increase of their use in industrial sectors, especially in the oil and gas industry. Coriolis meters are also one of the most accurate meters on the market, often getting flow readings within a 0.1 percent degree of accuracy. Most Coriolis meters are made up of two tubes that vibrate opposite to each other at a set frequency. They work by measuring the inertia created by gas or fluid flowing through the vibrating tubes. The inertia causes the tube to twist which changes the vibration. By measuring the change in vibration the mass flow rate can be derived. Sensors in the tubes detect the differences and then relay the information via electrical pulses. Due to their complexity, Coriolis meters are one of the most expensive meters on the market, but they do provide accurate readings of mass flow rate that are often essential in the industrial sector.