CONSIDERATIONS:
For a CFT34 + CFS flowmeter to measure standard/normal volume for gases:
- The meter needs to be in ‘fixed’ density mode (configured in menu C.1.2.3),
- The standard/normal density of the gas needs to be entered.
Once this has been done, the meter will then use this density with the mass flow measurement to calculate normal/standard volume flow. There are no normalized/standard volumetric flow units within the meter, but when measuring using the ‘fixed’ density, that is indeed what the measurement would be.
As an example, if I want to measure O2 flow in Nm3/hr I would use fixed density and have the meter output in ‘m3/hr’. The flow unit would show as ‘m3/hr’ but the measurement would indeed be ‘Nm3/hr’. The same would be for ‘SCFM’ or any other Normal/standard volumetric flow.
PROCEDURE:
In the Setup menu of the CFT34A transmitter, configure parameter C.1.2.2. Density Mode to Fixed, enter in C1.2.3 Fixed Density Value your fluid standard density, and set C6.5.1 Volume Flow to the actual volumetric flow unit of your choice. In other words, if the standard volumetric unit desired is Standard BPD for example, select Barrel/day in this menu.
To enter to Setup menu, in the transmitter’s local display press the Right arrow key (>) and keep it pressed until you see “Release key now” on the screen. Once you release the key, the display will read "quick setup".
Press the down arrow key two times so that "Setup" is shown on the screen. Press the right arrow key (>). Now you have entered to the Setup menu. The parameters mentioned above will be found in the following route:
Setup > Process Input > Density > Density mode.
Once you have changed the value to Fixed, press the right arrow key and then the down arrow key to go to Fixed density value (Setup > Process Input > Density > Fixed Density Value).
Enter the required density value for your gas. Press the right arrow key and then the the Return key (⏎) until you see "Process Input" displayed on the screen.
Press the down arrow key to configure your engineering units. This parameter will be found at the following route inside the Setup menu:
Device > Units > Volume Flow.
Once you have finished with your configuration, press the Return key (⏎) repeatedly to go back to Measure mode. At the prompt “Save Configuration?” make sure that YES is selected, and then say yes by pressing the Return key (⏎) again:
Image 1. Save Configuration message.
NOTE THAT:
Once the CFT34A transmitter is configured as explained, the transmitter will not be capable to read the actual density, as the density mode has been changed to Manual. As soon as you set Density mode to “fixed” the massmeter stops measuring the actual density… and because of that, if you map a dynamic variable to Density while in fixed density mode, what you will read from it is simply the number you manually entered in C1.2.3.
Questions: Help is available at FieldDevices-Support@se.com
