Thermal flow meters measure mass flow rate by means of measuring the heat conducted from a heated surface to the flowing fluid. Relying on the principle that a fluid flowing past a heated
temperature sensor removes a known quantity of heat as it passes, thermal flow meters measure either how much electrical power is required to maintain the temperature of the heated sensor or the
temperature difference between the heated sensor and the flow stream. Either of those values is directly proportional to the mass flow rate.
Thermal flow meters are used almost entirely for gas flow applications. Their design and construction make them popular for a number of reasons. They feature no moving parts, have nearly unobstructed
flow path, require no temperature or pressure corrections, and retain accuracy over a wide range of flow rates. Straight pipe runs can be reduced by using dual-plate flow conditioning elements and
installation is very simple with minimal pipe intrusions.
Selecting a Flow Meter
The basis of good flow meter selection is a clear understanding of the requirements of the particular application. Therefore, time should be invested in fully evaluating the nature of the process
fluid and of the overall installation.
- What is the fluid being measured by the flow meter(s) (air, water, etc…)?
- Do you require rate measurement and/or totalization from the flow meter?
- If the liquid is not water, what viscosity is the liquid?
- Is the fluid clean?
- Do you require a local display on the flow meter or do you need an electronic signal output?
- What is the minimum and maximum flow rate for the flow meter?
- What is the minimum and maximum process pressure?
- What is the minimum and maximum process temperature?
- Is the fluid chemically compatible with the flow meter wetted parts?
- If this is a process application, what is the size of the pipe?
If you have any questions or need any help selecting a flow meter, please contact us at sales@instrumart.com or 1-800-884-4967 to speak with an applications engineer.
