8. APPLICATIONS
8.1 Exposure to Anesthetic Gases
Because of the unique chemistry of the oxygen sensors provided with the MAXO2 Monitor, there are no significant effects when exposed to commonly used anesthetic gases, however, the monitor is not designed for exposure to flammable gas mixtures. (See WARNING page i)
8.2 Calibration Techniques in Pressurized Systems
Similar to other oxygen sensors, the Maxtec MAX series sensors measure the partial pressure of oxygen in a gas stream. This is correlated to read “percent oxygen” on the MAXO2 Monitors. It is important to note that the sensor output is directly proportional to the pressure of oxygen. Thus, one must take into consideration the effect of exposing the sensor to various gas sample pressures.
For example, if a monitor is calibrated to read 20.9% in ambient air (atmospheric pressure) and then exposed to a pressurized gas sample containing a known concentration of oxygen, the monitor will display a reading greater than the actual oxygen percentage. This is because the monitor was originally calibrated at atmospheric pressure (0 psig) then exposed to a higher pressure sample (eg, 5 psig). The greater the difference in pressure, the greater the difference in sensor signal (oxygen reading on the monitor).
By the same token, if a monitor is calibrated on a pressurized gas sample containing a known concentration of oxygen and then exposed to ambient air (atmospheric pressure), the monitor will display a reading less than the actual oxygen percentage.
To avoid confusion, the monitor can be calibrated at a single point on a gas stream similar to the application. If, for example, the purpose of the monitor is to measure oxygen in a concentrator or anesthesia application, the optimal results may be attained by calibrating the instrument on a gas of similar concentration and pressure. This would typically be done by connecting to a cylinder of a known high concentration of oxygen calibration gas and adjusting the flow and pressure to match the application before calibrating the instrument.
17