Aeroqual gas dilution calibrators can’t be used to calibrate CO2 because the scrubber media doesn’t remove ambient CO2 from the atmosphere. The CO2 module responds very quickly to calibration gas, and is also tolerant of dry (< 5 % RH) calibration gas. For these reasons, CO2 is the only gas module that can be successfully calibrated by direct injection of calibration gas into the gas inlet.
CO2 can be zero calibrated by direct injection of zero air from a certified zero air calibration cylinder, such as the A0194363 cylinder from Calgaz.
CO2 can be span calibrated by direct injection of CO2 from a calibration cylinder, such as the A0189932 cylinder from Calgaz.
Because Aeroqual AirCal systems aren’t being used, a different regulator is needed for direct injection.
There are two types of suitable regulators:
- Fixed or adjustable flow regulator
- Demand flow regulator
Fixed or adjustable flow regulator
A fixed flow regulator delivers gas at a fixed flow. You must choose the flow rate at the time of purchase. Aeroqual recommends the 715 fixed flowmeter from Calgaz. The 715 fits onto the zero-grade air and CO2 span gas cylinders.
You must purchase a flowmeter that has an outlet flow rate slightly higher than your monitor’s gas inlet flow rate. For example, if your inlet flow rate is 0.450 LPM, you should purchase the fixed flow regulator with a flow rate of 0.6 LPM.
You can also use the Calgaz 1768 variable flow regulator. This regulator is adjustable, meaning you can adjust the outlet flow rate to best match the inlet flow rate of your monitor.
Note: When using a fixed flow or adjustable regulator to deliver zero and span gas, the connection to the gas inlet must be via an open (uncapped) tee.
Demand flow regulator
A demand flow regulator allows the monitor to control the flow rate. If the inlet flow rate is 0.45 LPM, the demand flow regulator delivers exactly 0.45 LPM.
The Calgaz DFR 2001 demand flow regulator is suitable for use with the zero-grade air and CO2 calibration gas.
Note: When using a demand flow regulator to deliver zero and span gas, the connection to the gas inlet must be via a closed (capped) tee.