digitalYEWFLO Multivariable Vortex Flow Meter

Yokogawa’s digitalYEWFLO Multivariable Vortex Flow Meter can measure flow rate and temperature simultaneously, eliminating the need for separate components and associated installation costs. The embedded temperature sensor inside the shedder bar directly outputs the mass flow rate of saturated steam and computes the flow rate in real time based on the measured temperature.

Our multivariable vortex flow meter features:

  • Embedded temperature sensor
  • Built-in steam tables
  • Self-diagnostics functions
  • Simultaneous displays of mass flow rate and temperature on two-line LCD indicator


Embedded Temperature Sensor

With the digitalYEWFLO multivariable type vortex flow meter, there is no need for an external temperature sensor or the insertion hole in a pipe. An embedded Pt1000 RTD sensor extends the application of digitalYEWFLO to include the mass flow of saturated steam, gas, and liquids.

Built-in Steam Tables

Built-in steam tables provide temperature references for pressure based on the saturated steam conditions. With these steam tables, the measured temperature defines the steam pressure, and the temperature and pressure define the steam density. The mass flow rate is calculated by combining the steam density and volumetric flow rate.

With its Spectral Signal Processing system, the digitalYEWFLO is able to accurately measure fluctuations in temperature.

embedded temperature sensor

Advanced Self-Diagnostics

The LCD indicator provides messages to alert the operator if the temperature is outside the set range or if there is a temperature sensor fault, so necessary actions can be taken to prevent inaccurate measurements.

Simultaneous Displays of Mass Flow Rate and Temperature

The multivariable vortex flow meter displays mass flow rate and temperature on the two-line LCD indicator, providing simultaneous outputs for temperature monitoring and mass flow measurement. The LCD indicator also features user-selectable flow, temperature, total and other display parameters.



Steam Flow Measurement

Steam has often been described as the 'lifeblood' of the industry. The multivariable vortex flow meter is the perfect solution for steam flow measurement due to its embedded temperature sensor, built-in steam tables, inherent linear measurement, large turndown, low pressure drop, and high accuracy. The multivariable vortex flow meter eliminates the need for separate components and associated installation temperature elements. In addition, it provides quality, dependability and high pressure ratings along with a stable and reliable flow measurement.


How Multivariable Flow Meters Work

Saturated Steam Measurement Mechanism

A steam table provides data on the temperature, pressure and density of steam and is provided by a certification body such as ASME (American Society of Mechanical Engineers). The saturated steam curve shows the steam saturation point for each pressure/temperature level. The digitalYEWFLO converter calculates the mass flow rate using the density figure from the steam table. With its Spectral Signal Processing system, the digitalYEWFLO is able to accurately measure fluctuations in temperature. With superheated steam, density is calculated as a fixed pressure value that includes the superheated temperature value.


Measuring energy consumption is an important factor in the quest to improve energy efficiency. Efficient and accurate metering is paramount to determining excess use, along with an accurate picture of where the steam is being used. The more accurate and reliable measurements that are made, the more informed decisions can be taken that affect costs and product quality. Traditionally the most common method of steam metering is the orifice plate and differential pressure transmitter technique. General areas of concern with this type of measurement are the orifice plate's susceptibility to wear introducing immediate inaccuracies, the relatively high permanent pressure losses introduced into the system by the orifice place and the small measuring range, typically 3:1.

Yokogawa's digitalYEWFLO Reduced Bore Type Vortex Flow meter features a cast stainless steel body and a concentric reducer and expander that enable stable flow rate measurements in low-flow conditions. This expands the range of measurements that can be performed, from the higher flow rates down to the lower end of the flow span, which is normally difficult for Vortex Flow meters, and ensures stable and accurate flow rate output.


Vortex flow meters utilize a fluid phenomenon in which frequencies of Karman vortex streets released from a shedder bar inserted in a flow are proportional to flow velocities.

Yokogawa Technical Report

Progress in digital signal processing and network technologies has enabled advanced functions which cannot be achieved by traditional field devices with 4-20 mA signal, to be implemented on field devices. Standardization of international fieldbus specifications, notably the FOUNDATION™ Fieldbus, has enabled users to build optimum field networks comprised of freely chosen field devices from various device vendors.

Yokogawa Technical Report

Vortex flow meters have been appreciated by users as volume flow meters, which can, in principle, be applied to any flow measurement of liquid, gas, or steam. Volume flow measurement is enough for substances with small variations in density such as liquid. 

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