Post Mon Jan 01, 2018 7:56 pm

Check the accuracy of your humidity sensor

Hello,
here is a very easy way to check the accuracy of the humidity external sensor.

A simple, easy to do at home means of calibrating hygrometers uses standard salt and a sealed container. Table salt, when used properly, will maintain an exact 75% humidity in a perfectly sealed environment. So, to do this, you'll need three items. First, obtain an airtight container such as a see-through tub with a tight fitting snap-on lid (the kind usually found in most kitchens). Alternately, a heavy-duty zip-lock bag will do. Second, you'll need about a teaspoon of salt. Third, any small, shallow open container is needed (to hold the salt in) such as a screw cap from a plastic bottle.
Place the salt in its small container and add a few drops of water to moisten it. Don't dissolve it yet. With just a few drops of water, you'll get what you need, which is damp salt. Next, carefully place the salt in its small container, along with your hygrometer, into the airtight container. Please do not get any moistened salt on the gauge. Also, check to see that the starting point (current reading) is anywhere in the 40% to 80% range.
Seal the container tightly. Note: if you have any doubt as to whether or not it is a perfectly sealed environment, double-it-up by putting it in a second container, or into a second baggie. Do not try to remove the remaining air trapped inside. Now, wait for at least 5 or 6 hours until the environment has stabilized. Do not open the container. Read the gauge's humidity % level. It should be exactly 75%.