Changing flow meter's mode during the measurement

[bewprapaiwan]

Hi,

I have the CMOSens EM1 gas flow meter which can be setted to either temperature mode or flow rate mode. However, I will need both temperature data and flow rate (in ml/min) data in order to calculate the mass flow rate in kg/min. I am very new to LabVIEW so I have no idea what I can do. What I have in mind is ... doing the measurement with the sensor in temperature mode for ~ 1 second, then change to flow mode for ~ 1 second and change back to temperature mode and so on, until we stop the measurement. So output in data file might be something like this ...

Time   Data

0       temp

1       flow

2       temp

3       flow

...       ....

where temperature and flow data can be in different column. Note that the fastest sensor response time is 5 ms.

Any suggestion what I can do in LabVIEW??

Thank you so much in advance.

Bew         

[SnowMule]

Why not a thermocouple in the flow path and use a TC01 to make the temp measurement? You'll also need a pressure sensor if you want volumetric measurement instead of standard flow. 

Kinda sounds like the device you have isn't the right one for the application.  We use TSI flow meters here and the serial interface is easy to interface to LabVIEW, configure them once when you open the port and just take readings.  They also have an analog output. 

[bewprapaiwan]

Hi SnowMule

Thank you for your suggestion. The data from flow meter is already in volume per minute so I only need to know density of gas at temperature T to find mass flow rate (...do I miss anything?). It's nitrogen gas and there's some online database availble to get the gas density from known temperature. That's why I want to read the temperature from the flow meter as well.

Additional thermocouple would be a solution if I cannot have LabVIEW to do the job for me.

Thanks again!