Oxygen Equipment User Manual

8. APPLICATIONS

8.1 Exposure to Anesthetic Gases

Because of the unique chemistry of the oxygen sensors provided with the

MAXO

2 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 MAXO

2 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.

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