Honeywell VA201T Calibration Handbook page 52

Calibration Handbook
Adjust the flow rate to 0.5 L/min.
Connect the tubing from the regulator to the sensor calibration cap. See Figure 1.
If the gas is not allowed to flow for at least 3 minutes, it will affect the calibration accuracy.
The next screen allows you to specify the span calibration gas concentration value.
Use the arrow keys to increase or decrease the value and press enter to select.
The next screen requests confirmation.
Let the gas flow for at least 3 minutes before starting the calibration.
Press enter to confirm and the screen displays the concentration during calibration.
A success or failure message displays and the screen returns to the main menu option.
Menu
* *
Set Zero
Set Gas
200 ppm
Set Span
198 ppm
52
Set Zero
Z1
Set Span
Yes
3
E Point