9
Wet Bath Accuracy Checking
Using wet bath simulators for accuracy checking has been the accepted method for
many years. Breath alcohol simulators are specially designed water-alcohol
instruments which provide equilibration of alcohol between water and air at a controlled
temperature.
Accuracy checking of the MARK V should be performed by authorized persons using
any NHTSA approved breath alcohol simulator.
To perform a wet bath accuracy check:
1. Pour 500 ml of 0.080% Certified Solution into the glass jar.
2. Attach a piece of tubing (6 -
8” long) to simulator inlet. Attach a regular or check-
valve mouthpiece to the end of this tubing.
3. Attach a 1 -
2” piece of tubing to the simulator outlet. Attach a mouthpiece to the
other end of this shorter tubing. Make sure the connection is air-tight.
Note: The length of tubing connected to the simulator outlet should not be
longer than 2” in order to prevent condensation.
4. Plug Simulator in and turn switch to the ON position.
5. Allow the solution to heat.
6. After 15 - 20 minutes, check the thermometer. The thermometer should read
34ºC when ready.
7. Attach instrument to the mouthpiece. (The opaque moisture trap can be used
should condensation appear in the mouthpiece).
8. Switch on the MARK V. Wait for
“Please Blow” to display. Connect to outlet tube.
9. Forcefully blow into the simulator for several seconds, press the green button and
release.
After a few seconds, the measured value will be displayed. The display should read
0.080% +/-0.005.
NOTE: If the result is not within published specifications for the MARK V , conduct
another accuracy check. Verify that the seal on the simulator is air-tight and that the
outlet tube and mouthpiece are free of condensation. If the measurement is still not
within specifications (+/- 0.005), the unit must be removed from service until an internal
calibration can be conducted.
