RH350/355 V2.1 8/08

5

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

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

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

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

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.