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HDC1080: How to identify if it is condensation situation or humidity reduce situation ?

Part Number: HDC1080

Hi 

Condensation and  humidity reduce, in both case the HDC1080 reading will decrease. How to differentiate these two cases? 

Thanks!

PY Tsai

  • Howdy PY Tsai,

    And welcome to the e2e forums!  HDC1080, and humidity sensors in general are meant to measure relative humidity in non-condensing ambient environments. If condensation does occur on the device, then the device may temporarily relay an RH value of '0'.  Upon receiving this value, it is recommended to turn the heater on to burn away any condensation that may have developed on the sensor opening.

    Please let me know if this answers your question.

    Best Regards,

    Matt

  • Hi  Matt,

    When condensation occur what will the RH value behave? will it go to "0" immediately or it will gradually reduce to "0"?

    Regards,

    PY Tsai

  • If water condenses on the sensor, the RH output will read 0. As stated above, since the sensor is meant to measure relative humidity in a non-condensing environment, the heater must be turned on to help evaporate any condensation that will develop on the sensor as it would affect RH readback.

    Best Regards,
    Matt
  • Matt,

    You did not answer my question. 

    When condensation occur what will the RH value behave? will it go to "0" immediately or it will gradually reduce to "0"?

  • Hi PYTsai,

    Thank you for the reply and I have reworded the response to provide clarification.  To reiterate, the HDC devices are only meant to read humidity in non-condensing environments, so you must ensure that no condensation or liquid enters the sensor opening.  If condensation does develop on the sensor and saturates the sensor, the RH output will immediately read as "0".  In this instance, the microcontroller attached to the device must enable the heater bit of the sensor to burn off this condensation.  Once the condensation evaporates from the sensor opening, the humidity sensor will return to normal operation and readback humidity information.

    Please let me know if this answers your question, and if so please press the verify button.

    Best Regards,

    Matt

  • Hi Matt,

    Can you help duplicate this case from your site by put HDC1080 on top of a cup of hot water like the picture shown below?   

    You will then see %RH goes up to 100%  (due to condensing is happening ) and then gradually reduce to 0%. 

    We need to find a way to identify when such condense situation is happening. thanks!

  • Hi PYTsai,

    Thank you for your post. I'll forward this information to the correct internal path. I have a few questions regarding the experiment:

    -May I know the duration that it took to reach 0 from 100% RH?

    A temporary solution can involve the use of a microcontroller to verify if 99-100% RH is achieved, and after of which briefly turn on the internal heater to prevent any condensation. In applications such as these it is common to have a fan that helps drive away condensation for accurate readings, since the sensor must be in a non-condensing environment for accurate reads.

    Best Regards,
    Matt
  • Matt,

    it took 15 secs to reach 0 from 100%RH when condensation happen. 

    Regarding to your suggestion: 

    1. How long should we turn on the internal heater to prevent condensation? and what is the frequency? 

    2. If no fan, only turn on the heater will this solution works?

    Thanks!

    PY Tsai

  • Howdy PYTsai,

    There is no fixed number when activating the internal heater, and may be dependent on customer application.  During activation, the temperature and humidity value should be monitored, and when the humidity value recovers, you can disable the heater.  The chip will have to cool to reach the environmental temperature.  May I ask what type of application you are using the HDC1080 device in? Are you expecting condensation, or just trying to find ways to prevent in the case of condensation? 

    Best Regards,

    Matt