Of fact, there is no one-size-fits-all technology that can be used to meet all operating needs, performance, and conditions.
There are at least 8 common gas flow measurement technologies being used today, all with their strengths and limitations. Costly errors can be avoided by recognizing the benefits and drawbacks of each.
Electromagnetic Flow Meters
Faraday’s Law of induction is used by electromagnetic flow meters to detect flow. An electromagnetic flow meter contains an electromagnetic coil that produces a magnetic field as well as electrodes that capture electromotive force (voltage). Due to the forces caused by induction, the electromagnetic field varies as the fluid passes through the pipe. The flow rate is then calculated based on these adjustments.
Pros:
- Temperature, pressure, density, and viscosity of the liquid have no effect.
- Capable of detecting contaminated liquids (solids, air bubbles).
- There is no loss of pressure.
- There are no moving parts (improves reliability).
Cons:
- Without electrical conductivity, magnetic flow meters are unable to detect gases and liquids.
- A short straight pipe portion is required.
Electromagnetic flow meters are typically employed in the food industry, chemical applications, natural gas supplies, and power utilities since they are unaffected by pressure, density, or temperature variations.
Vortex Time Flow Meter
A mechanism known as the von Krmn effect is used in vortex flowmeters. When flow passes over a bluff body, it will alternately form vortices, according to this principle. The front of a bluff body is broad and flat. A bluff body is a piece of material with a broad, flat front that projects vertically into the flowstream in a vortex meter.
The frequency of the vortices determines the flow velocity. The flowrate is derived by multiplying the pipe area by the flow velocity. To reduce distorted flow patterns and swirl, vortex meters may necessitate the installation of straightening vanes or straight upstream piping. Low flowrates are a challenge for vortex meters because they produce uneven vortices at low flow rates.
Vortex meters range in accuracy from medium to high, depending on the model and manufacturer. In addition to liquid and gas flow measurement, vortex flowmeters are widely used to measure steam flow.
- The vortex flowmeter has no moving parts, and the measuring component has a simple structure, reliable performance and long service life.
- Thermal characteristics such as temperature, pressure, density, and viscosity of the fluid being measured have no effect on the volumetric flow rate of the vortex flowmeter.
- It has a wide range of uses because it measures the flow of liquids, gases, or vapors.
- There isn’t much pressure loss as a result of it.
- It performs poorly in terms of anti-vibration. Vibrations from outside the vortex flowmeter might create measurement inaccuracies.
- The fluid’s high flow velocity shock creates vibrations in the vortex body, lowering measurement accuracy.
- Only clean media can be measured.
- For mounting, straight pipe is required.
- Not appropriate for fluids with a low Reynolds number.
- The pulsing flow is incompatible.
Vortex flowmeters are most typically employed in power production and heat-supply systems such as compressed air, saturated steam, superheated steam, and other similar systems.
Paddle Wheel Flow Meter
A turbine flow meter is what this is called. Paddle wheel flow meters are classified mechanically into two categories.
- With a water wheel configuration, tangential-flow flow meters.
- With a windmill structure, axis-flow paddle wheel flow meters.
The paddle wheel’s flow and revolutions are proportionate to each other. Thus, the number of revolutions can be used to calculate the rate of flow by spinning the paddle wheel with the force of the flowing stream. Pulses can be recovered as signals by inserting a magnet in the rotation axis and on the edge of the paddle, translating the number of revolutions into the flow rate.
- Performance that is consistent.
- Flow can be measured in either direction.
- Clean fluids are required. Particulates can obstruct the paddle’s ability to spin effectively.
- To get the most accurate results, you’ll need a turbulent flow profile.
Paddle wheel flow meters are most commonly employed in fume scrubbers, reverse osmosis, and a variety of other applications.
Thermal Dispersion Flow Sensor
Heat is used to quantify the flow rate of a fluid in thermal dispersion flow meters. The typical structure has a heating element in the middle and two temperature sensors on either side. As gas flows, heat is transferred in the flow direction, and the temperature sensor upstream “gets colder,” while the temperature sensor downstream “gets hotter.” The difference between the temperature sensors can be used to calculate the flow rate.
- The measurement was really precise.
- The entire error band is small.
- Not appropriate for measuring liquid flow.
- When detecting gases at high temperatures (>50oC), this method is not ideal.
Respiratory devices, anesthetic equipment, CPAP devices, and central gas monitoring systems are some of the common uses found in the medical and industrial industries.
- ESRF-ESF: This sensor with bidirectional gas flow sensing of up to 300 ln/min is appropriate for medical, process, and pharmaceutical equipment and is based on the hot-film anemometer principle for mass gas flow measurements.
- ESRF-HF: The ESRF-HF is a family of mass flow transmitters that can measure gas flow quickly and accurately across a large dynamic range. Its small size, combined with the ruggedized stainless-steel housing, makes it perfect for use in limited locations in industrial applications.
Floating Element Flow Sensor
This is one of the most basic flow measurement systems. Float in a tapered pipe is the most common approach. A differential pressure is created when fluid is pressed between the tapered pipe and the float, causing the float to move correspondingly. The flow rate can be determined by reading the meter’s visual scale.
- Measuring by hand
- Not suitable for measuring high flow rates.
They’re best utilized for: A wide range of applications, including chemicals, compressed air, and other gases.
Ultrasonic Flow Meter Type
Ultrasonic flow sensors use ultrasound and the Doppler Effect to determine the volumetric flow rates of a wide range of fluids.
This technology is extremely precise and is unaffected by the medium’s pressure, temperature, or viscosity. In idle mode, the transmitter sends ultrasonic waves through the pipe, which are detected by the ultrasonic sensor. Because there is no fluid movement, the received signal has the same frequency as the transmitter. Once the flow begins, the received waves have a frequency that is either greater or lower (depending on the flow direction) than the one transmitted.
- Low-cost maintenance.
- Fluids that do not reflect ultrasonic frequency cannot be measured.
Ultrasonic flow sensors have a wide range of applications, from process flow to custody flow.
Differential Pressure Flow Meter
Bernoulli’s equation is used by differential pressure sensors to estimate flow through capacitive pressure sensors. Differential pressure flow meters establish an artificial constriction with laminar plates, an aperture, a nozzle, or a Venturi tube, then measure the pressure loss of fluids as they move through that constriction. The flow rate is proportional to the pressure drop. These tough, precise meters are suitable for a variety of clean liquids and gases.
Further reading: Pressure Sensors: Capacitive vs. Piezoresistive
Differences and their implications
- Measurements that are precise.
- Operation that is dependable.
- Not appropriate for measuring liquid flow.
- Induced pressure drop is required for operation, which could be avoided using other methods.
Best used in: Many industries, including power supply, food & beverage, medical, aerospace, and HVAC, use them because of their compatibility.
- Silicon capacitive technology is a high-precision technology.
- Stability over time.
- High tolerance for overpressure.
Coriolis Mass Flow Meter
The use of a vibrating tube where the passage of gas can induce variations in frequency or phase shift proportionate to the mass flow rate is the primary operating principle of coriolis flow meters. The tube vibrates at a predetermined frequency when it is not in use. The vibration of the tube changes proportionally to the flow rate of the medium when the fluid flow begins. Sensors placed along the tube measure the change in vibration, which is then converted to flow rate.
- Measurement of true mass flow.
- Pressure, temperature, and viscosity have no effect.
- There are no inlet and output portions needed.
- Vibrations in the environment create measurement mistakes.
They are commonly used in a variety of industrial industries that require the measurement of hygienic and corrosive but somewhat clean gases.
What method do you use to calculate natural gas flow?
A flow meter measures gas flow and should have excellent accuracy, minimal pressure loss, and direct mass flow readings. Boiler/burner control, fuel-to-air ratio, and custody transfer applications all benefit from high-quality natural gas monitoring. In the end, the more precise your natural gas measurements and gas flow management are, the more money you will save on natural gas expenditures.
Sierra’s immersible thermal, mass vortex, and thermal mass flow controllers are known for their excellent precision, low pressure drop, and direct mass flow measurements. With a 100:1 turndown and no moving components, our mass flow meters are perfect for precision natural gas measurement, making them a reliable MFC option. Through our cryogenic mass vortex meters, our natural gas flow measuring instruments can also handle liquefied natural gas (LNG).
What instrument was used to measure gas flow?
A gas flow meter, also known as a gas flow monitor, is a device that monitors the volume or mass of gas flow. Gas flow monitors are used in a variety of industries to measure gas flow in natural gas pipelines, compressed air lines, and manufacturer’s gas lines.
What method do you use to calculate flow rate?
When choosing a tankless water heater, the flow rate is crucial.
Although we can estimate a flow rate based on the number of bathrooms in your home, it’s always preferable if you can give a flow rate measurement.
To measure your water flow rates, follow the steps below.
Required Equipment
- 1 gallon container (if you can’t find a 1 gallon container, any other container would suffice as long as you know how big it is and can convert it properly)
- A stopwatch, a smart phone, or some other type of timer
Instructions for measuring the water flow rate at a faucet or shower
- Turn the faucet on.
- Using a stopwatch or your phone, time how long it takes to fill the container (in seconds).
- Divide 60 by the time it took to fill your container (for example, if it took 30 seconds to fill, 60/30 = 2 gallons per minute).
- The result is the application’s flow rate in gallons per minute.
If you want to run multiple applications with your tankless water heater at the same time (for example, two showers), you’ll need to measure each application and sum the flow rates together. Individual flow rates can decrease when numerous applications are operating at the same time, thus turning on the water for all applications you intend to run at the same time before measuring individual flows is a smart idea.
What is the definition of gas flow rate?
A gas flow rate is the amount of gas that passes through a given site in a given amount of time.
Chemical engineering and process engineering both make heavy use of gas flow rate calculations. Because pipes vary in diameter along their length, calculating flow rates via them can be difficult. Any type of gas may be calculated using the same fundamental formulas.
What type of sensor may be used to determine flow rate?
A flow meter (also known as a flow sensor) is a device that measures the linear, nonlinear, mass, or volumetric flow rate of liquids or gases.
What is the purpose of a natural gas meter?
The cubic foot is a popular unit of measurement for natural gas, and you’ll be paid in thousands of cubic feet (MCF) or hundreds of cubic feet (CCF). You could also be charged by the therm, which is roughly equivalent to a CCF or 100 cubic feet. The utility sets a meter between the incoming electric power or gas lines and the point of distribution at the house to monitor how much electricity or gas you consume.
The force of moving gas in the pipe drives a gas meter, which turns quicker as the flow increases. The pointer on the next higher value dial advances one number for every complete round of the dial with the lower value.
When reading a gas meter, read and write down the numbers from left to right on the dials (opposite of an electric meter). It’s vital to observe that the hands of adjacent dials on both types of meters turn in opposite directions.
How can you figure out how much water is flowing via a pipe?
How can you figure out the volume flow rate in a pipe? The speed of the liquid flowing through the pipe is multiplied by the cross-sectional area of the pipe.
How do you work out flow rate based on pressure?
The radius of the pipe should be squared. With a radius of 0.05 meters, for example, 0.05 2 = 0.0025. Multiply this result by the pressure decrease in pascals over the pipe. 0.0025 x 80,000 = 200, for example, with a pressure decrease of 80,000 pascals.