what is a wet bulb

Discussion in 'Incubating & Hatching Eggs' started by florasbell, Jul 13, 2011.

  1. florasbell

    florasbell Chillin' With My Peeps

    May 1, 2011
    i have read lots of post contaning the words WET BULB what is a wet bulb? i have never seen them in shops or even heard of them before
    1 person likes this.
  2. Gypsy07

    Gypsy07 Chillin' With My Peeps

    Feb 4, 2010
    Glasgow, Scotland
    A wet bulb thermometer is used to measure relative humidity. It has to be used alongside a normal thermometer for comparison. And it's the kind of old fashioned thermometer that has the bulb of liquid at the bottom and the thin glass stem that the liquid is squeezed up as it heats and expands.

    What you do is get some kind of wicking material a couple of inches long, and you put one end over the bulb at the bottom of the thermometer and the other end you hang in a glass of water so that the liquid is drawn up the wick to the thermometer bulb.

    Because of evaporation, the wet bulb will always measure a slightly lower temperature than the dry bulb of the other thermometer. The drier the atmosphere, the quicker the evaporation rate, and the lower the wet bulb reading will be. The more humid the atmosphere, the slower the evaporation rate, and the higher the wet bulb reading will be. But it will always be lower than (or in 100% humidity equal to) the dry bulb reading.

    So you note the dry bulb reading adn the wet bulb reading, and then you use RH (relative humidity) tables to find out what the humidity is.

    It's very accurate, but more complicated and more time consuming than just getting a hygrometer that reads humidity as a percentage.
  3. Arielle

    Arielle Chicken Obsessed

    Feb 19, 2011
    Massachusetts, USA
    Interestingly, the preferred method to measure humidity in the big hatcheries is the wet bulb thermometer method, according to some university sources.

    I already have the glass bulb type thermomters; I will add 6 inches of cotton shoe lace and tie over bold and set end in sup of water.

    Also, do remember to check the egg itself for the correct amount of increase in the air cell.
  4. cmom

    cmom Hilltop Farm

    Nov 18, 2007
    My Coop
    Quote:I use a wet bulb. I also have a hygrometer in my incubator for comparison.

    Last edited: Jul 14, 2011
  5. Tammy N

    Tammy N Chillin' With My Peeps

    Oct 9, 2011
    Florence Oregon
    Bump up for us oldies and newbees wow i feel like i am learning every day here we never did this 20+ yrs ago Thanks

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