Product information
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usbdrdaq.en r4
Basis of the calibration method
Calibration relies on the general physical properties of saturated solutions. The
humidity above such solutions in closed containers is known quite accurately and is
used to calibrate the sensors. Chemical salts used for this purpose include potassium
chloride, magnesium chloride and magnesium nitrate.
Note:
The humidity that exists above all such solutions varies with temperature.
The standard solutions may be harmful to your skin, eyes or when
swallowed. Take all necessary precautions to avoid contact when
preparing and using the standard solutions.
Note:
For the highest accuracy you should compare the readings from you DD101 with
the readings from a calibrated 'laboratory standard' reference humidity gauge.
Calibration of the sensor involves:
Preparation of the calibration equipment.
Measurement of the standard saturated solutions.
Creation of calibration data for the USB DrDAQ software.
A check that the calibrated sensor is accurate.
Note:
You must measure at least two different standard solutions to provide two or
more fixed points for calibration.
Equipment you will need:
USB DrDAQ with DD101 sensor
Pico DD100 Temperature Sensor
At least two Standard Solutions
A label for the DD101
A test container
An insulated box
A stand for the DD101
[Optional] high-accuracy, calibrated reference 'laboratory standard' humidity gauge
Stand
It is very important that the standard solution does not enter the case of the DD101.
The solution may damage the electrical components of the sensor. Therefore the
DD101 needs to be suspended in the test container clear of the standard solution. A
small stand is the best way to hold the sensor above the solution. The stand may be
any object (open framework) that is impervious to the standard solution. Make sure
that the material that your stand is made from is compatible with the test solutions
you intend to use.
Test container
Your test container should be only just big enough to hold the DD101 and DD100
sensors, the stand, and a small quantity of standard solution (the solution should fill
approximately 5% of the volume of your container). It will also have to be water-tight
with a seal that allows you to pass the leads for the sensors into the container.
Note: The smaller your container, the more quickly the humidity will stabilize. You can
reduce the time taken for the system to stabilize by forcing the air in the container to
circulate. This will require a fan that does not introduce heat into the container (it
must be driven by a shaft or magnetic coupling so that the motor is outside the
container).
