Overview of Multivariable Transmitters
Multivariable transmitters are a DP transmitter with the ability of not only measuring differential pressure, static pressure, and temperature but other values as well. These values are known as independent process variables, which are used to compensate when there are changes in the media’s density, viscosity, as well as other flow parameters when used as a mass flow meter. When used as a differential flow transmitter, it measures pressure, temperature, and DP pressure all at the same time. This allows the device to, in real time, calculate the compensated mass flow. This allows for more accurate readings as compared to typical differential pressure transmitters, which lose precision due to their inability to measure the pressure and temperature variations. It also has a turn down value of 14:1 as compared to most typical DP transmitters with a turn down ratio of 4:1, which allows for greater accuracy across a larger flow range.
Pros of a Multivariable Transmitter in Flow Measurements
- Compensated flow readings, able to handle changes in pressure and temperature in the system, allowing for accurate readings
- Simultaneous calculation allowing for “Real-time” data
- Cost effective, efficient alternative to purchasing three different measuring devices
- Higher flow accuracy, and higher flow turndown than a typical DP transmitter
- Capabilities include being able to measure Mass, Volumetric flow, Energy Flow, Totalized Flow, DP Pressure, both Gage and Absolute Static Pressures, and Process Temperature
- An optional output of HART 4-20mA
- Can be used with Gas, Steam, and Liquids