Most standard measurement technologies for flow metering use volumetric techniques. Examples include positive displacement meters and turbine meters. The value displayed on such a meter’s output (e.g. a display screen) equates to a quantity in a volumetric measurement unit like GPM or LPM. For many applications, a preferred flow measurement would be mass units. Mass is preferable to volume for purposes like batching and mixing chemicals, monitoring emissions, and custody transfer. Using volumetric flow meters for applications like this demands the inclusion of conversion step to translate volumetric units into mass units. That typically requires the multiplication of a volumetric reading by a density value. Density is not a constant, though. It changes based on temperature for liquid materials and based on both temperature and pressure for gaseous ones. Density changes can make volumetric measuring inaccurate. This problem can be avoided by using mass flow meters that directly measure mass without relying on any density-based calculations.
The ability to monitor and control flow conditions is critical to many different process conditions in an industrial setting. Accurate flow meters make it possible to maximize production, product quality, and efficiency. In many situations, flow measurements can be used as an effective gauge of overall performance. This can be done thanks to the law of conservation of mass, i.e., the mass entering a system must be equal to the mass leaving the system as long as each mass is measured over the same length of time. Metering mass flow and transmitting it plays a key role in managing plant operations.
As noted above, many of the most common meters used to measure flow – including Ultrasonic, Magnetic, Differential pressure, Variable area, Positive displacement, Turbine, and non-compensated Vortex meters – read flow volumetrically. They’re often combined with sensors measuring temperature and pressure in order to compute true mass flow electronically. This is why such meters are considered “indirect;” they rely on multiple measurements and calculations to derive a mass flow measurement. Direct mass flow measurement is often considered unfeasible due to stringent application parameters. SmartMeasurement™, though, can provide mass flow measurement solutions to fit any need.
Direct Mass flow measurement are Coriolis and thermal flowmeters such as SmartMeasurementTM’s Coriolis flowmeter family of ALCM meters with various flow tube construction to best fit any application used mainly for liquids. While in gas measurement SmartmeasurementTM’s, ATMF family of thermal mass flow with direct mass flow and temperature outputs are the smart solution for any gas applications.
In steam measurement, the only technology able to measure mass flow is a self-compensated vortex flow metes. The ALVT family of vortex flow meter produced by SmartMeasurement can take direct mass flow readings on steam flow with built-in temperature and pressure sensors well as mass flow transmitter. These flow meters are perfect for steam flow measurement because when steam temperature and/or pressure changes the output is the actual mass flow of the steam. Non compensated vortex meters or other volumetric flow meters will not measure the true mass flow of steam when steam temperature and/or pressure changes.