Calibrating hygrometer

Discussion in 'Incubating & Hatching Eggs' started by Chicken Woman, Dec 26, 2008.

  1. Chicken Woman

    Chicken Woman Incredible Egg

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    Carefully place the cup containing the salt/water mix in a re-sealable plastic bag. Place the hygrometer in the bag, away from the cup of salt and water. Note: make sure none of the salt/water mix comes in direct contact with the hygrometer, or the hygrometer may be damaged. Completely seal the bag.
    Place the sealed bag aside at room temperature for 8-12 hours. Pick a location free of drafts, out of direct sunlight, and away from heating or cooling vents. The temperature should be fairly constant.

    Hygrometer should read 75 %
     
    Last edited by a moderator: Dec 26, 2008
  2. Buster

    Buster Back to Work

    This is interesting to me. What ratio salt to water do you mix? Does the hygrometer calibrate itself this way or do you do something to it?
     
  3. Chicken Woman

    Chicken Woman Incredible Egg

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    You just add a couple talespoons of salt and enough water to make it kind of a loose paste.
    It doesn't calibrate but it tells you how close to correct it is so you can either up it or down accordingly.
    Some are adjustable but if not you will just keep in mind that you need to have yours so many points higher or lower to be correct.

    Hope that doesn't sound stupid, just hard to explain.[​IMG]
     
    Last edited by a moderator: Dec 26, 2008
  4. Buster

    Buster Back to Work

    Thanks for the explanation!
     
  5. silkiechicken

    silkiechicken Staff PhD Premium Member

    So what is the refernece point? What is it supposed to read? 100% humidity? 50%?
     
  6. millebantam

    millebantam Chillin' With My Peeps

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    75% I believe.
     
  7. Chicken Woman

    Chicken Woman Incredible Egg

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    Yes it's 75 % sorry I didn't include that important fact ! DUH !
    How to Calibrate a Hygrometer
    By Lianne McLeod, DVM, About.com

    IIf yours is the adjustable type, adjust the screw or setting so that it would have read 75 percent. You will have to do this very quickly, or remember how much you need to adjust the setting (e.g. for mine, it read 72 percent when it should have been 75 percent, so I would need to set it ahead by 3 percentage points). You may want to put the hygrometer back in the bag for another 8 hours to double check your adjustment.
    If yours is not adjustable (like mine), simply make a note of how "off" your hygrometer reads. If it reads below 75 percent, you will need to add the difference to your actual readings. If your hygrometer read above 75 percent on the calibration, you will need to subtract the difference from your actual reading.

    Here are some examples to help:

    Case 1: after sitting in the bag for calibration, my hygrometer read 72 percent. It should have read 75 percent, so the difference is 3 percent. I will now add 3 percent to the readings I take on the hygrometer (e.g. in a tank) to get the actual relative humidity.

    Case 2: after calibrating in the bag, a hygrometer read 80 percent. It should have read 75 percent, a difference of 5 percent. I would have to subtract 5 percent from readings when using the hygrometer to get an accurate relative humidity.

    Remember: always give a hygrometer about 2 hours to stabilize before taking a reading, as changes in the relative humidity may take a while to register accurately on a hygrometer.
     
    Last edited by a moderator: Dec 26, 2008
  8. skeeter9

    skeeter9 Chillin' With My Peeps

    Thanks for posting this - it reminds me that I haven't done mine in a while!!!! [​IMG]
     
  9. Buster

    Buster Back to Work

    Cool! It's all clear to me now. I will calibrate mine as soon as this hatch is over.
     
  10. Jamie821

    Jamie821 Chillin' With My Peeps

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    the mixture I use to calibrate is one half cup salt one fourth cup water in coffee cup and stir.
     

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