| A
hygrometer is an instrument used to measure relative humidity.
Relative humidity is a measure of how much water the air is
holding, relative to the maximum amount of water the air could
possibly hold at a given temperature.
Because of the delicate design of hygrometers,
it is easy for them to become innacurate. A simple method
of calibrating your hygrometer will help ensure you are measuring
the relative humidity as accurately as possible. Hygrometers
should be calibrated yearly.
Hygrometers are available in both digital
and dial models, and both should be checked for calibration.
Some dial types will have a small screw or adjusment on the
back so you can adjust them after calibration. If there is
no way to adjust them, make a note of the calibration result,
and then you can simply add or subtract from the actual reading
to get a more accurate humidity level.
To calibrate a hygrometer you will need:
* 1/2 cup table salt
* approximately 1/4 cup water
* coffee cup
* hygrometer
* large re-sealable freezer bag
Place 1/2 cup of salt in the coffee cup, and
add the water. Stir for a bit to totally saturate the salt.
The salt won't dissolve in this amount of water; instead,
the salt should have the consistency of wet sand.
Carefully place the salt/water mix in a re-sealable
plastic bag, along with the hygrometer. 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.
After being in the sealed bag for 8-12 hours,
check the reading of the hygrometer. It is best to read it
while still in the bag, since if your house air is dry the
reading may go down quickly once you take the hygrometer out
of the bag.
The relative humidity in the sealed bag with
the salt/water mix should be 75 percent. My hygrometer read
about 72 percent.
What
are Hygrometers? | How
to Calibrate a Hygrometer | Hair
Hygrometer | Recording
Hygrometer | The
use of The Hygrometer |
