Model 306 Ozone Calibration Source™

Picture
The 2B Technologies Model 306 Ozone Calibration Source™ is a portable source of ozone that allows you to calibrate any ozone monitor - not just those manufactured by 2B Tech.  The instrument scrubs ozone from ambient air and produces any mixing ratio of ozone in the range 30 to 1,000 ppbv.  The desired ozone concentration is chosen from the easy-to-use menu using a rotary select switch, or can be controlled remotely via the serial menu.  The total output flow rate is in the range 3.0-3.2 L/min volumetric, and the ozone mixing ratio is controlled so as to be independent of ambient temperature, pressure, and humidity.  You can attach the Ozone Calibration Source (OCS™) output directly to the inlet of any ozone monitor; the excess flow is vented through an ozone scrubber internal to the OCS.  Although the instrument comes calibrated against a NIST-traceable ozone standard, the menu allows the user to change the calibration parameters of the ozone output if desired.  For example, if you maintain an ozone reference instrument in the lab, you can use the OCS as a transfer standard for calibrating ozone instruments in the field relative to your lab standard.  The scheduler function allows you to schedule an autocalibration once daily that executes a series of up to 10 programmable output steps.

The Ozone Cal Source™ is housed in the same small, rugged instrument case as the Model 202 and Model 205 Ozone Monitors™.

Some applications of the Model 306 Ozone Calibration Source™ include:
  • Calibration of ozone monitors in the field.  This highly portable transfer standard is especially useful for maintaining the calibrations of networks of ozone monitors.
  • Testing of materials such as rubber, plastics and paint for effects of ozone exposure.
  • Studies of the effect of ozone on plants where a calibrated source of ozone is required.

We recently published a paper in the journal Atmospheric Measurement Techniques describing the Model 306.  It may be downloaded here.


Example Data

Picture
Measured ozone concentrations for "stair step" changes in Ozone Calibration Source Output.

The following figure shows the 4 calibration curves produced from the 4 sets of increasing and decreasing ozone concentrations.  The data points and lines for the 4 least squares fits, which are plotted in different colors, overlap so well that it is difficult to distinguish them.  The equations for the linear regressions show that the slopes of the  4 individual calibration curves agree to better than ±1% and the intercepts agree to ±2 ppbv.  Correlation coefficients (R^2) are all 0.9999 or 1.0000.
Picture
Four calibration curves obtained using the same instrument. Notice the excellent reproducibility.

Application Note

In the example described in the brief writeup below, researchers use a Model 306 Ozone Calibration Source to deliver constant ozone exposures to skin samples.  The controlled study yielded new insights into the mechanism by which ozone pollution causes skin inflammation and conditions such as eczema, psoriasis, and acne.  


Specifications

 Method of Ozone Production  UV Photolysis of O2 at 185 nm
 Ozone Concentration Range  0 ppbv and 30 ppbv to 1,000 ppbv
 Precision and Accuracy of   
 Output		  Greater of 2 ppbv or 2% of ozone concentration
 Response Time for Change in
 Ozone Output Concentration		  30 s to reach 95% of concentration change
 Flow Rate  3.0-3.2 Liter/min volumetric
 Power Requirements  12 V dc or 120/240 V ac, 18 watt
 Size  3.5 x 8.5 x 11 inches (9 x 21 x 29 cm)
 Weight  5.6 lb (2.6 kg)
 Analog Output  Yes; voltage output tracks ozone output and provides system error codes
 Serial Connection  Yes; for remote operation and system diagnostics
 Programmable Output  Yes; user-specified ozone output for up to 10 steps from 0 to 1,000 ppbv; stored in internal memory
 Scheduler  Yes; once-daily execution of the step program at user-specified hour
 Baud Rate  4800