Specifications

GDC-150 Operation Manual
18 5209-9000 Rev 0
5.5. Calculating the Span Gas Value
To achieve calibration the user must first tell the GDC-150 what concentration of span
he is going to flow over the sensor. Within the transmitter, this is a voltage setting.
The range of 0-4 VDC is equal to the full measurement range of the sensor. Prior to
attempting to calibrate, determine the voltage value required.
Use the following formula to calculate the voltage required.
Therefore, in this example, the required voltage setting to calibrate a 0-2000 ppm
sensor with 1000 ppm is 2.0 VDC.
NOTE: When calibrating solid-state sensors for combustibles or
refrigerants, the span gas must be humidified. The use of a
humidification chamber is required. The humidification chamber sits in
line between the cylinder of span gas and the calibration adapter.
Remove the sponge inside t
he chamber and wet it under the tap.
Squeeze out the excess water so it is not dripping wet and place it back
inside the chamber. As gas flows through the chamber, it absorbs water
which acts to humidify it and the humidified span gas flows over the
sensor. See page
21 for ordering information.
NOTE: Values for
Calibration Span Gas and Sensor Range in the
above equations must have the same Engineering Units (e.g., PPM, %
of LEL, % vol, etc.).