I found this forum : How to connect MPXV5004DP (pressure sensor) to Arduino Uno - Sensors - Arduino Forum which someone posted with a similar project. This is the only post I have been able to find so I am wondering how plausible and successful this method is and I am worried as I have no way to calibrate my measurements to make sure the pressure equations used in the code will be accurate to my application...
Any advice? Or thoughts?
(Code from forum post above is shown below)
[// untested code
// The offset voltage is 1.0V when there is no pressure difference.
const float offset = 1.0;
// The sensitivity is 1.0V per kPa for the sensor.
const float sensitivity = 1.0;
// assume the analog pressure sensor is connected to A0.
const int pinSensor = A0;
...
int rawADC = analogRead (pinSensor);
float voltage = (float) rawADC / 1023.0 * 5.0; // voltage at Arduino pin. Range is 5V, 10 bits.
float pressure = (voltage - offset) / sensitivity; // differential pressure in kPa
// Some magical calcuation for the windspeed (just as an example)
float windspeed = sqrt ( 2.0 * pressure / 1.2 );]
I think you should look for an air-velocity or wind-speed sensor. Or, at least research how they are made...
I have a feeling that the pressure differences will be too small to be measured accurately and there are probably lots of uncertainty in the variables/values if you try to use Bernoulli's equation (which I probably knew at one time, but don't remember).
If I were trying to build something from scratch, I'd use a propeller and monitor the RPMs. But, it would have to be calibrated, somehow.
Or, somebody was recently doing a project using the speed of sound (to which air speed is added/subtracted). That could be done without independent calibration, but again I'm not sure about the accuracy of "small" measurements...
Okay thank you for the input I will look more for air flow sensors, the other issue I face is that I need to log the data over a few months and most sensors I find are instantaneous and don't log.
Sensor is one part, logging is another. Data can be logged, and all sensors put out data.
I assume you don't want to pay for proper HVAC tools, hence trying to cobble one together. Ignore the data logging. Get data first. Logging is simple once you get to that point.
If you are interested in any accuracy at all, anything you come up with (like using a differential pressure sensor across a restriction) will need to be calibrated against a professional flow meter of some sort.