RH350 Datasheet, PDF (5/6 Pages) Extech Instruments Corporation. – SuperHeat Psychrometer

CALIBRATION
The following verification and calibration procedures require the 33% and 75% RH reference
bottles which are supplied with the Model RH355 kit.
Accuracy Verification
Checking the 33% or 75% RH Calibration
1. Insert meter’s sensor into the 33% or 75% salt reference bottle
2. Check the reading after a minimum of 10 minutes
3. Verify that the reading is within the accuracy specification
Relative Humidity Calibration (33% and 75%)
33% Calibration
1. Turn the meter Off.
2. Insert the meter sensor into the 33% salt reference bottle.
3. Allow the meter one hour to stabilize.
4. While holding down the [Mⁱⁿ/AVRST] button, press and hold the [ON/OFFSET] button
for 2 seconds to enter calibration mode.
5. “32.8%” (reading may vary depending on operating temperature) will flash on the
LCD screen. After 30 minutes, the flashing will stop to indicate that the 33%
calibration is complete. Note: To exit from the calibration procedure before
completion, pressing the [ON/OFFSET] button will turn the meter off.
6. Proceed to the 75% Calibration below.
75% Calibration
1. Insert the meter sensor into the 75% salt reference bottle.
2. Allow the meter one hour to stabilize
3. Press and hold the [Mⁱⁿ/AVRST] button for 2 seconds to enter the 75% calibration.
4. “75.3%” (reading may vary depending on operating temperature) will flash on the
LCD. After 30 minutes, the flashing will stop to indicate that the 75% calibration is
complete.
5. Turn power off. Calibration is now complete.
Note: Frequently check the water level in the salt bottles. Both the 33% and 75%
bottles should be completely saturated with some water present. The bottles are
sealed and not refillable.
RS-232 PC Communications Interface
The meter is equipped with an RS-232 PC interface jack (3.5mm phono) for connection to
a PC. The cable to connect the meter to the PC is included in the optional 407752 data
acquisition kit. The kit includes Windows^TM compatible software that allows the user to
store readings in a text file and display real-time measurements in a series of selectable
formats. For more information or specific operating instructions, refer to the User Guide
included with the 407752 kit or contact Extech Instruments.
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RH350/355 V2.1 8/08