Flow
Measurement

Simultaneous measurement of mass flow, density, temperature and viscosity

Simultaneous measurement of mass flow, density, viscosity, and temperature opens entirely new perspectives for process control, quality assurance, and plant safety.

Coriolis flow measuring principle:

Each Coriolis flowmeter has one or more measuring tubes that an exciter causes to oscillate artificially. As soon as the fluid starts to flow in the measuring tube, additional twisting is imposed on this oscillation due to the fluid’s inertia. Two sensors detect this change of the tube oscillation in time and space as the “phase difference”. This difference is a direct measure of the mass flow.

In addition, the fluid density can also be determined from the oscillation frequency of the measuring tubes. The temperature of the measuring tube is also registered to compensate for thermal influences. The process temperature derived from this is available as an additional output signal.

Benefits:

• Universal measuring principle for liquids and gases
• Multivariable measurement – simultaneous measurement of mass flow, density, viscosity, and temperature
• High measuring accuracy: Typically, ±0.1%, optionally ±0.05% with special
  calibration
• No inlet/outlet runs required
• Measuring principle independent of the physical fluid properties and the flow profile

For additional information please feel free to contact our team directly.

Robust and universally applicable for liquids, gases, and steam

Vortex flowmeters are used in all industries to measure the volume flow of liquids, gases and steam. Applications in the chemicals and petrochemical industry for example, in power generation and heat-supply systems involve widely differing fluids: saturated steam, superheated steam, compressed air, nitrogen, liquefied gases, flue gases, carbon dioxide, demineralised water, solvents, oils, boiler feedwater, condensate etc.

Vortex flow measuring principle:

The measuring principle is based on the fact that turbulence forms downstream of obstacles in the flow. Inside each vortex flowmeter, a bluff body is therefore located in the middle of the pipe. As soon as the flow velocity reaches a certain value, vortices form behind this bluff body, are detached from the flow, and transported downstream. The frequency of vortex shedding is directly proportional to the mean flow velocity and thus to volume flow. The detached vortices on both sides of the bluff body generate alternately a local positive or negative pressure that is detected by the capacitive sensor and fed to the electronics as a
primary digital, linear signal.

Benefits:

• Universally suitable for measuring liquids, gases, and steam
• Largely unaffected by changes in pressure, density, temperature and viscosity
• High long-term stability: no zero-point drift and lifetime calibration
• Large turndown of typically 10:1 to 30:1 for gas/steam, or up to 40:1 for liquids
• Wide temperature range: -200 to +400°C (+450°C on request)

For additional information please feel free to contact our team directly.

Direct mass measurement of industrial gases, compressed air, and aqueous fluids

Whenever high turndown or low-pressure losses are important in gas metering applications in any industry, thermal mass flow meters offer a real alternative to traditional measuring techniques, whether for process control, consumption and supply monitoring, detecting leaks, or monitoring distribution networks. Using insertion versions, it is also possible to measure gas flows in very large pipelines or in rectangular ducts.

Thermal mass measuring principle:

This measuring principle is based on the fact that heat is drawn from a heated body when a fluid flows past. A thermal flow meter contains two PT100 temperature sensors for this purpose. One sensor measures the current fluid temperature as a reference. The second sensor is heated and has a constant temperature differential relative to the first sensor at “zero flow”. As soon as the fluid begins to flow in the measuring tube, the heated temperature sensor cools off due to the fluid flowing past – the higher the flow velocity, the greater the cooling effect. The electric current required to maintain the temperature differential is thus a direct measure of mass flow.

Benefits:

• Direct measurement and display of mass flow and fluid temperature
• No pressure or temperature compensation required
• High turndown (100:1)
• Excellent low-end sensitivity
• Quick reaction to fluctuations in flow

For additional information please feel free to contact our team directly.

Versatile and economical flow measurement of gases and liquids

Using ultrasonic waves, the volume flow of a wide variety of gases and liquids can be measured reliably, independent of electrical conductivity, pressure, temperature or viscosity.

Ultrasonic flow measuring principle:
Swimming against the flow requires more power and more time than swimming with the flow.

This simple fact is the basis for ultrasonic flow measurement according to the “differential transit time” method. This method uses two sensors, set opposite each other in the measuring tube. Each sensor can alternatively transmit and receive ultrasonic signals, while simultaneously measuring the signal transit time. As soon as the fluid in the tube starts to flow, the signals are accelerated in the direction of the flow but delayed in the opposite direction. This differential transit time, measured by the two sensors, is directly proportional to the flow rate.

Benefits:

• Measurement independent of pressure, density, temperature, conductivity and viscosity
• Free pipe cross-section, no pressure loss
• No moving parts, minimum maintenance, and upkeep
• Long service life, no abrasion or corrosion from the fluid
• In-line or clamp-on design for stationary or temporary flow measurements

For additional information please feel free to contact our team directly.

Calorimetric Flow Switches

Safe monitoring of flowrates with no moving parts

Calorimetric (Thermal) Flow Switches offer the benefit of no moving parts and practically no pressure loss. They are used for monitoring and displaying the relative mass flow rates of liquid media in the range from 0.03 to 3 m/s. Endress+Hauser supplies the following models for standard and hygienic applications:

• Flowphant T DTT31 − with threaded connections or compression fitting 
• Flowphant T DTT35 − with process connections for hygienic applications

Measuring principle:

The Flowphant measures the mass flow of a liquid medium using the calorimetric measurement method. The calorimetric measuring principle is based on the cooling of a heated temperature sensor. Heat is removed from the sensor by forced convection due to medium flowing by. The extent of this heat transfer depends on the flow velocity of the medium and the difference in temperature between the sensor and the medium (King’s Law). The higher the flow velocity or the mass flow of the medium, the greater the temperature sensor cooling.

Applications: 

• Monitoring of cooling water circuits of pumps, turbines, compressors and heat exchangers 
• Monitoring of pump functions 
• Leak monitoring in process pipes 
• Monitoring of lubrication circuits 
• Filter monitoring in the beverages industry

Benefits:

• Virtually zero pressure loss
• FieldCare for quick configuration and reliable storage of device settings 
• Optional: 4 to 20 mA analogue output for outputting the flow as a percentage 
• Optional: second switch output or 4 to 20 mA analogue output for temperature monitoring 
• Onsite function check and process information with a digital display on the device 
• Top housing section which can be rotated 310° and rotatable display mean measured values can be read in all installation positions 
• Marine approval 
• 3-A mark and EHEDG certificate for DTT35

Please note the EMC also supply the Weber Flow-Captor range of calorimetric flow switches

For additional information please feel free to contact our team directly.