Teledyne MX300-I Manuel D’Utilisation

37 

investigation should be made until the discrepancy in readings is 
resolved. The troubleshooting section of this manual may provide 
additional assistance in locating the problem. 

 

The MX300-I oxygen monitor provides a variety of built-in safety 

features that prevents its use when a fault is detected. When a unit displays 
the message √ SENSOR and sounds the audible and visual alarm 
continuously, it is an indication of a faulty connection between the sensor and 
the unit or an expired or faulty sensor. To determine where the difficulty lies, 
refer to the following guidelines in Table 3-1.  

New sensor responds 
slow or drifts.  

 

 

If the sensor is new 
and was just 
removed from its 
sealed bag it may 
need to run for 
several hours. 

A)  Wait 1–2 hours and 

recalibrate. 

 

Sensor will not read 
below 22 % after 
calibration in 100% O2. 

Calibration in 100% 
was invalid or the 
room air is 
contaminated with 
excess oxygen. 

 

A)  Recalibrate using dry gas 

making sure the reading 
stabilizes before making 
any adjustments. 

B) Make sure that at least 6" 

(30 cm.) of tubing is 
attached to the exhaust 
side of the tee adapter to 
prevent back filling. O2 flow 
rate should not exceed 5 
l/min. 

C) Oxygen concentration at the 

sensor is significantly higher 
than 21%. Take the 
instrument to a well-
ventilated area and check