Pressure Sensor Choice - DeeEmm/DIY-Flow-Bench GitHub Wiki

Selecting pressure sensors.

You can use a wide range of pressure sensors. There are many different types available that will work. For example there are lots of sensors packaged up for use in Arduino projects on breakout boards that can be used. We have included several different footprints in the PCB to cater for a wider range of sensors. You can also connect them using pin headers.

The biggest consideration when choosing a sensor is the range of the sensor (its Full Scale Deflection or 'FSD'). If the range of the sensor is an order of magnitude larger than the range you need to measure, then the sensor will have a poor resolution as it is only reading across a very small portion of its overall range. This will directly impact the quality and accuracy of the results.

We recommend the NXP MPXV7007DP pressure sensors as they have a range of +/- 7kPa (28"/wg) which is the same range as a professional flow bench. It should also be noted that the sensor we have chosen will read both positive and negative values. This is important as the bench will change from vacuum to pressure when reversing the air flow to test exhaust port flow. You can still use a regular sensor that only has a vacuum range, however you will need to swap the tubing over when you change flow direction.

An alternative to these are the XGZP6899A007KPDPN (shown above) which also have a +/- 7kPa range. These are manufactured by Sencoch and are available via AliExpresss. It is worth noting however that generally only the 5 or 10 kPa versions are listed, you may need to ask for the 7kPa version. Also be aware that these sensors are not pin compatible with the MPXV7007DP. These will fit the official shield, but just something to bear in mind in case you need to adjust your own custom wiring or shield design.

Absolute pressure sensors can also be used. These are generally used for measuring barometric pressure and so will generally have an ambient reading of 100kPa (typical atmospheric pressure) with the pressure range extending above and below that value. This effectively gives you a +/- range centered around 100kPa

The +/- range is also very useful for pitot probes, which will then display results as high pressure and low pressure areas.