Using a thermal mass flow meter, gas flow is measured entirely differently, eliminating the need to correct pressure and temperature. The heat transfer is measured by thermal mass flow meters when gas flows past a heated surface. Heat transfer occurs when gas molecules come in contact with heated surfaces, so the larger the number of gas molecules, the greater the heat transfer. Due to this, this method of flow measurement is independent of gas pressure and temperature and is dependent only on the number of molecules in the gas.
These devices work by using two temperature sensors. The first is used as a reference and the second is used as a measurement of the gas temperature. A slight temperature difference is maintained above the temperature sensor by heating the flow sensor. During gas flow past the heated flow sensor, heat is transferred. As a function of the mass flow rate, the instrument determines the amount of power needed to maintain a temperature differential. Due to the low amount of heat generated, this is a safe technology for natural gas, hydrogen, and other flammable gases.
Thermal mass flow is an inferred flow measurement. These meters measure heat transfer and then calculate the mass flow rate based on the NIST traceable calibration. A known amount of gas is passed through the sensor during calibration to measure its signal. Over the meter’s operating range, this process is repeated several times.
Thermal mass flow meters have the following benefits:
- Pressure and temperature corrections are not required for mass flow measurement
- Excellent sensitivity at low flow rates
- Turndown capabilities that are high
- Installation is simple
Meters come in different styles, technologies, abilities, etc. There is no single meter that can do it all – but they all serve a purpose.
Gas Flow Meters
Gas flow meters also called gas flow monitors, measure gas flow by volume or mass and are used to measure gas flow in natural gas pipelines, compressed air lines, and manufacturer’s gas lines. Several types of gas flow meters exist, including optical, which uses light beams to measure how fast particles in a gas move, pressure, which measures the difference in gas pressure before and during a flow restriction to measure flow rate, and mechanical, in which the flow pushes on a part of the meter, which then calculates flow rate based on its movement. Prior to purchasing a gas flow monitor, it is important to know what it will be used for. Mass of flow rate or volume, continuous flow rate or totalized flow rate, minimum and maximum flow rates, temperature, and whether precise measurements are necessary or if reliable, repeatable measurements are sufficient are all factors to consider.
About silverinstruments
With Silver automation instruments, you can solve a wide range of industrial process challenges in agriculture, water, wastewater, factory process control, oil & gas, and electric power generation. They have installed their products in a wide range of installations both internationally and in the US. The measurement instrumentation is safe, reliable, and of high quality in domestic and foreign courts.
JIANGSU RUNYI INSTRUMENT CO., LTD is the parent company of Silver automation instruments. Silver exports process instruments worldwide, while RUNYI manufactures its parts. In addition to covering a 50000 square meter area, RUNYI also has a standard workshop and office building measuring 4000 square meters. With a registered capital of 30 million RMB, the company has a total area of 50000 square meters.
In addition to their ISO9001:20008 International Quality System Certification, all of their products are manufactured following strict procedures. Their close ties to Nanjing University of Science and Technology and Chang Zhou University ensure that instrumentation technology continues to develop continuously. A number of patent certificates have been obtained in the field of process instrumentation.
