• Check the expected value of the standard you will be using to calibrate your device. (For this demonstration the value of the dry gas standard we used was .080% - see True-Cal display on preceding page).

• Check the temperature of the Alco Sensor IV - it must be within a specified range in order to perform the calibration. 
  
  You can quickly check the temperature of your instrument by inserting a mouthpiece into the Alco Sensor IV and observing the displayed temperature.

Mouthpiece inserted and temperature displayed

• Most Alco Sensor IV instruments have a subject test operating temperature of 10°C to 40°C. These instruments require the temperature of the unit to be between 23°C and 27°C to perform a calibration, If your instrument does not allow you to perform a calibration when it is in this temperature range check the operator's manual for your specific device to determine what calibration temperature range is allowed. Eject the mouthpiece after you have determined the temperature of the unit by depressing the red mouthpiece eject button.  DO NOT ever pull the mouthpiece out without pressing the red button. If the instrument temperature has proven to be within the proper temperature range, Then we may proceed with a calibration sequence. If not, you will have to either warm or cool the instrument so that it reaches the appropriate temperature before proceeding.

• Remove the battery cover located on the front of the Alco Sensor IV by gently pressing down on the cover.  Inside the battery compartment, directly above the 9-volt battery, there are three (3) small holes.  Locate these holes. For the purpose of this discussion, we will call them calibration switches.  We will call the hole to the left Switch #1, the middle hole Switch #2, and the hole to the right Switch #3.

Battery cover removed

• Locate the calibration tool in the carrying case of your Alco Sensor IV. The calibration tool is a small plastic peg.  During the calibration procedure, the calibration tool will be used to depress the calibration switches.   The switches should be pressed gently to avoid damaging them. You will feel the switch activate.
• Obtain a clean Alco Sensor IV mouthpiece and remove the plastic packaging.  Inspect the mouthpiece
  to ensure no plastic is obstructing either end of the mouthpiece. 

Calibration Switches with Cal Tool

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