Volumetric flow measurement from the stack


Thread Starter


Hi all,

We need to measure the volumetric flow of exhaust gas from our stacks. The stacks are about 80 meters high (including the HRSG) and 5 meters in diameter. The exhaust gas is about 110 degrees Celcius.
Any recommendations on companies and measurement methods to choose from would be appreciated.

This application is generally done using insertion thermal or insertion turbine meters. FCI is known for thermal meters, InFLOW, INC., EMCO, FTI, and Thermo make insertion turbine meters. The thermal meters are slower response and have lower temperature limits. The turbines have moving parts (generally not used on relief valve lines). Both types have been very successful on this service.

John Catch

Rohit Chandak


Selection of flow meter on a stack depends mainly on the velocity, temperature, moisture etc. Some of the common flow meters used on Stack are Multi Point Thermal Mass Flow Meter, Averaging Pitot Tube / VERABAR; Insertion Turbine (especially on small diameter stack); on flare stacks Ultrasonic Meters.

To have Volumetric & if the velocity is good enough (more than 15 ft/sec) I would highly advice to use NON-CLOG Design VERABAR Flow Element (Averaging Pitot Tube). This will also be a cost effective solution. We have several installation all over the world & have installed on very large line sizes too. Visit us at http://www.chandakinstruments.com or http://www.veris-inc.com to know more about the products.

If the velocity is less & Mass Flow Measurement is acceptable you can also look at option of installing two two-point thermal mass flow meters opposite to each other wherein signal runs to a single flow computer. This would be a MASS Flow Metering. For multipoint I will only advice Kurz Instruments, Inc. USA multipoint thermal mass flow meters. Let me have process parameters to suggest the best option.

rohit @ chandakinstruments.com