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H7625B; H7635B,C; H7655B DUCT-MOUNT AND OUTDOOR-MOUNT HUMIDITY/TEMPERATURE SENSORS
7 63-2579—3
CALIBRATION
All transducers are factory calibrated to meet/exceed published
specifications. Field adjustment should not be necessary.
IMPORTANT
• Do not verify comparative RH with a sling
psychrometer. Too many variables exist which
induce errors into this process.
• Recalibration must be done in a controlled
environment. Relative humidity must be held
stable while making any adjustment.
• Verify the device output directly with calibrated
instrumentation and verify RH with calibrated
instrumentation. Never use a controller output.
• With correct power applied, and only a meter
connected to the transducer output, ensure that
the output is proportional to the true RH.
Using Increment/Decrement Switches
Increment RH Output
This DIP switch allows you to calibrate the sensor through
the software. The switch must be toggled from the Off to
the On position and then returned to the Off position for
an increase of 0.5% RH. This means that if your humidity
has drifted 1% lower over a certain time period, you can
toggle the Increment RH Output switch (2 times) in order
to slide the whole curve upward 1%.
Decrement RH Output
This DIP switch allows calibration in the same way as the
Increment RH. The difference is that each toggle results
in a decrease of 0.5% RH.
Using Calibration Trim Potentiometers
IMPORTANT
• Due to sensitive nature of humidity calibration,
adjusting trimmer potentiometers is not highly
recommended.
• Calibrate only in a stable humidity/temperature
chamber of laboratory grade.
Single Point Calibration
IMPORTANT
Use only one of the following two options.
OPTION 1
1. Select a controlled humidity environment between
10 and 40 percent RH. Be sure humidity is stable.
2. Adjust zero trimmer (z).
OPTION 2
1. Select a controlled humidity environment between
40 and 70 percent RH. Be sure humidity is stable.
2. Adjust span trimmer (s).
Two Point Calibration
1. Select a controlled humidity environment between
10 and 40 percent RH. Be sure humidity is stable.
2. Adjust zero trimmer (z).
3. Select a controlled humidity environment between
70 and 75 percent RH. Be sure humidity is stable.
4. Adjust span trimmer (s).