Use LM35 to measure temperature of flowing gas

Andrew Dorogi

Other Parts Discussed in Thread: LM35

What's the best way to use an LM35AH/NOPB to measure the temperature of air? We're measuring air temperature as it flows through a tube. Air temp can change at up to 5C/min. We expose the leads by standing the LM35 off of a small circuit board, position it so the leads are in the flow stream, and minimize the size of the circuit board (to minimize thermal influence on the leads). Is the sensor response a function of the lead temperature only? Does the mass of the LM35A body have to reach the air temperature for the output to match the air temperature? We have about 10C lag during a 5C/min change.

over 10 years ago

0 Aaron Heng over 10 years ago

TI__Mastermind 31600 points

Hi Andrew,

I will look into this, and get back to you soon.

Aaron

0 Aaron Heng over 10 years ago in reply to Aaron Heng

TI__Mastermind 31600 points

Hi Andrew,

I’m sorry for the delay. Based on the selected package LM35AH/NOPB, this package should do a fine job measuring the air temperature. The metal can package usually dominates the thermal path through package where the GND connected to the case; therefore, a small circuit board is not necessary required. It’s used for harsher and higher temperature environment.

Regard to your 10°C lagged, I would need to see your setup. Could you please provide me some information?

Hope this helps. Please let me know if you have further question.

Aaron

0 Andrew Dorogi over 10 years ago in reply to Aaron Heng

Prodigy 20 points

Thanks Aaron - is it possible to have a private webex meeting with you?

0 Aaron Heng over 10 years ago in reply to Andrew Dorogi

TI__Mastermind 31600 points

Hi Andrew,

Could you please give several date and time? I will try to accommodate your schedule.

Aaron

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Use LM35 to measure temperature of flowing gas