6
Measuring Relative Humidity with the
Microscanner
™
D501
A unique benefit of the Microscanner
™
D501 is its ability to measure wet
and dry bulb tem peratures faster and more accurately than ever before.
A Relative Humidity Kit is available as an accessory. Contact Industrial Sales
Customer Support for more information. This kit is comprised of a calculator
card and a tube of water. The calculator card incorporates two circular
membranes, an RH calculator and a Dew Point calculator.
The Microscanner
™
is used to measure the wet bulb and dry bulb
temperatures of the atmo sphere. From these two temperatures, both the
relative humidity and the dew point can be calculated.
To calculate Relative Humidity:
1. Wet the absorbent membrane identified as WET with a few drops of water
(a small tube of tap water is provided with the kit).
2. Rapidly wave the card in the air for several seconds. This assures that the
water on the wet membrane is evaporating at its maximum rate.
3. With the Microscanner
™
in the MIN mode, quickly measure the
temperature of the WET membrane immediately after you stop waving it.
This is the atmosphere’s wet bulb temperature.
4. Set the Microscanner
™
in the SCAN mode and measure the DRY spot.
This is the atmo sphere’s dry bulb temperature.
5. Use the calculator card as directed to com pute the relative humidity and
dew point.
Fahrenheit to Celsius Conversion
The D501 Microscanners
™
are equipped with a convenient method for
Fahrenheit/Celsius conversion:
1. Find the small hole on the left side of the red display filter.
2. Insert the end of a straightened paper clip into the hole and push to
activate the small switch underneath.
3. While holding the paper clip pressed into the switch, turn the instrument on
by pressing the red POWER ON button.
4. Remove the paper clip.
5. The instrument now reads °C instead of °F. To return to the original
setting, simply repeat the process. Each time you repeat the process, the
instrument switches between °F and °C.
