Differential pressure using MP3H6115

[lifteliten]

Hi,

I'm currently using two MP3H6115a to meassure differential pressure. I'm using this pressure to calculate air speed.

The problem is, that my differential pressure is not constant over time. I've been evaluated the sensors today after having problem with the speed. I've been having the sensors on my desk all day, writing down the estimated pressure from respective sensor, and over time the difference vary from 0.05kPa to 0.01kPa. The frequency of the change is very slow, and it have been constant for long periods (~2h).

Maybe worth noting is that the pressure has been falling all day.

Does anyone have experience on the matter? Is this to be expected?

/ Tom

[andresbarrilado]

Hi Tom,

The 6115 has an expected error of 1.5%, which means roughly 1.5kPa. Variations in the order of .05 to .01 kPa, are normal.

Refer to http://cache.freescale.com/files/sensors/doc/data_lib/DL200.pdf?fsrch=1&sr=1, page 3-176, Pressure Error Band for more info.

Best of lucks!
Andres

[lifteliten]

Hi Andres.

Thanks for the answer, I never really looked at that figure since i've used this sensor before and with good results. I had to calibrate them, and they've worked ok! But the ones I have now have non-linear output from pressure, so it is impossible to calibrate.

Can you point me in the direction of a more reliable set up for determine dynamic and static pressure using freescale sensors?

Best,

Thom