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DIY Touch Screen Trimix Analyser

Discussion in 'Making your own Gear' started by stevetto, Feb 10, 2021.

  1. stepfen

    stepfen Contributor

    # of Dives: 200 - 499
    Location: Greece
    751
    563
    Indeed, I was unaware of this particular board hence I didn't know/notice it can be supplied from the battery directly. My bad.
     
  2. stevetto

    stevetto Registered

    59
    46

    ESP32 is much powerful than arduino nano but the lcd refreshing is still challanging.
     
  3. stepfen

    stepfen Contributor

    # of Dives: 200 - 499
    Location: Greece
    751
    563
  4. Jarek Andrzejewski

    Jarek Andrzejewski Registered

    # of Dives: 100 - 199
    Location: Poland
    18
    4
    Does volume (speed) of flowing gas impacts the helium reading or it doesn't matter?
     
  5. stevetto

    stevetto Registered

    59
    46
    You are right! The speed of flow influences the reading of the thermal conductivity sensor.
    And the pressure in your tank influence the flow rate.
    To minimize the error you can:
    - use low flow rate
    - use a constant flow rate flow restrictor (flow is constant regardless of the tank's pressure)
    - fix your flow restrictor at a certain position and always analyze full tanks (same pressure same flow rate)
    (the flow rate is viscosity dependent, and viscosity depends on the mixture)
    ( calibration and analysis has to be made at the same flow rate)
    - or you might can fill the chamber with gas, wait the readings to stabilize, stop flow, cover the exhaust holes, wait a bit and maybe you can get better results

    I do not know how big the influence of these factors. It need to be tested.
     
    lucca brassi likes this.
  6. stevetto

    stevetto Registered

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  7. stevetto

    stevetto Registered

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  8. stevetto

    stevetto Registered

    59
    46
    It has not been calibrated to Helium.
    For nitrox I use 3 points calibration.

    60hOwukA2P5yp3I5m9XZyff5MSULpTCLbNHkY4JiVWiXpAskLRtMyXSf2NyOOHBTO-WfRxw=w1161-h880-no?authuser=0.jpg
     
  9. stevetto

    stevetto Registered

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  10. stevetto

    stevetto Registered

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