Differential Pressure Sensor Recommendation for Two-Phase (Air + Water) Flow Measurement – Arduino Compatible

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Hi everyone,

I'm currently working on an experimental setup involving two-phase flow (air and water) in a closed system, and I need to measure the differential pressure between two points along a small pipe section.

Here’s what I’m looking for in a sensor:

  • Type: Differential pressure sensor (not absolute)
  • Medium: Must be suitable for wet or moist air, ideally capable of handling both air and water contact (two-phase flow conditions)
  • Pressure Range: Preferably up to 500 kPa or below
  • Output: Analog voltage (0–5V, 0.5–4.5V, etc.) or digital (I2C/SPI) that is compatible with Arduino UNO/Nano
  • Update Rate: Fast enough to capture dynamic pressure changes caused by bubble/slug movement
  • Form Factor: Can be integrated easily in a lab setup, ideally not too bulky

So far, most differential pressure sensors I’ve found are targeted for air only (e.g. MPX10DP, MPX5010DP, MPX5100DP, etc.), and not rated for liquid use. Some industrial-grade sensors exist, but they tend to be quite expensive or hard to integrate with Arduino.

:magnifying_glass_tilted_left: What I Need Help With:

  • Has anyone worked with a differential pressure sensor suitable for two-phase flow?
  • Can you recommend any Arduino-compatible sensors that are:
    • Suitable for liquid and air,
    • Withstand pressures up to 500 kPa or slightly lower,
    • Available for purchase (e.g., AliExpress, DigiKey, Mouser, etc.)?
  • Alternatively: Would it make sense to use two waterproof absolute pressure sensors (upstream & downstream) and calculate the difference in software?

I'm also open to hearing about DIY ideas or precautions in case I want to use standard air pressure sensors with some sort of isolation from the fluid.

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That is easy as gravity will help. Use a "T" in the fluid line the pipe at the "T" point is pointing upward and is several inches long. Mount the sensor at the end of the vertical pipe. The trapped air will be compressed by the fluid and will keep the fluid from the sensor and the sensor will show the fluid pressure. The pressure gauge on my irrigation system has worked that way for many years. Same with the pressure gauge on the house water supply.

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