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Inexpensive co2 sensors — Parallax Forums

Inexpensive co2 sensors

ArchiverArchiver Posts: 46,084
edited 2002-08-12 23:05 in General Discussion
Hi ,

Does anyone know where I can get a decent CO2 sensor for a relatively
good price ?

Thanks,

Vince

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2002-08-12 21:24
    At 07:56 PM 8/12/2002 +0000, you wrote:
    >Hi ,
    >
    >Does anyone know where I can get a decent CO2 sensor for a relatively
    >good price ?
    >
    >Thanks,
    >
    >Vince
    >
    >Vince -

    What's the application - airborne, dissolved, etc. and how much room do you
    have to work with ?

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  • ArchiverArchiver Posts: 46,084
    edited 2002-08-12 21:25
    The application is airborne...mostly for green houses.

    Vince

    --- In basicstamps@y..., Bruce Bates <bvbates@u...> wrote:
    > At 07:56 PM 8/12/2002 +0000, you wrote:
    > >Hi ,
    > >
    > >Does anyone know where I can get a decent CO2 sensor for a
    relatively
    > >good price ?
    > >
    > >Thanks,
    > >
    > >Vince
    > >
    > >Vince -
    >
    > What's the application - airborne, dissolved, etc. and how much
    room do you
    > have to work with ?
    >
    > >To UNSUBSCRIBE, just send mail to:
    > > basicstamps-unsubscribe@y...
    > >from the same email address that you subscribed. Text in the
    Subject and
    > >Body of the message will be ignored.
    > >
    > >
    > >Your use of Yahoo! Groups is subject to
    http://docs.yahoo.com/info/terms/
  • ArchiverArchiver Posts: 46,084
    edited 2002-08-12 23:05
    At 16:25 08/12/02, enzom2000 wrote:

    >Does anyone know where I can get a decent CO2 sensor for a relatively good
    >price?
    >The application is airborne...mostly for green houses.

    http://www.google.com/search?&q=%22carbon+dioxide%22+sensor

    returns a load of results.

    I've had some industrial experience in sensing CO2 at levels present in the
    atmosphere and have never found a "cheap" solution.

    Bear in mind a sensor is only a start. You need a pump to move your air
    sample thru the sensor, a good (!!) filter to eliminate dust getting into
    the sensor, and you must assure a noncondensing atmosphere in the
    sensor. Vibrating aquarium pumps placed on the inlet side work well, but
    check airflow periodically and be prepared to replace or rebuild the pump
    when the rubber cups wear and crack. Also bear in mind that sucking air
    thru the wall of a greenhouse to a sensor just outside can result in
    cooling it enough to cause condensation. You need to keep all parts of the
    system inside the environment being measured, or else provide a
    condensation trap before the sensor. Water (or dust) in the sensor is a
    really big No-No.

    Also bear in mind when selecting a sensor that the typical atmospheric
    concentration for CO2 is 370 ppm and select a sensor (or complete
    instrument) that works and gives acceptable accuracy and resolution in this
    range. You'll find instruments meant for high range measurements around
    2.5% (25,000 ppm) to be useless - cheaper, but useless for resolving small
    changes in normal atmospheric levels.

    Your own breath will have a very strong effect on the reading if you exhale
    anywhere near the intake. I advise placing the display unit 5 - 10 feet
    (downwind if applicable) from the air intake.

    Jim H
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