Alco-Sensor III Accuracy Check Procedure - Page 3

Alco-Sensor III (serial # > 1200000)

  1. You should know the expected value of the standard – this will be used to compare against the actual result determined by the instrument.

True-Cal device displays .081. This is the expected value of the Standard used for this demonstration

Expected value = .081


  1. Carefully attach Alco-Sensor III to mouthpiece assembly
  2. Submit a gas sample from the standard to the Alco-Sensor III for at least six (6) seconds. On the 4th or 5th second of the six second count, depress and release the READ button.

(NOTE: The vapor must be flowing through the mouthpiece when the READ button is depressed and it is suggested that it flow for at least one second after the READ button has been depressed).



Submit a gas sample

READ button is depressed


  1. Carefully detach the Alco-Sensor III from the standard and observe the displayed reading until it becomes stable and bright. This is the final result. 
  2. The difference between the final result and the expected value of the standard should be within the tolerance allowed in the Quality Assurance Plan set for your program.
  3. If the difference is greater than the specified tolerance, the unit requires a calibration adjustment.  (Follow the instructions for CALIBRATION).
  4. The expected value of the standard used for this demonstration was .081, so our result of .080 is within an acceptable tolerance

Observe final reading 
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