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Voltmeter Connection
Connect the Snifit to a voltmeter using the supplied
Data Cable (see Figure 1). We suggest using a 3½
digit or greater Digital Multimeter having a 2 VDC
range or auto ranging capability, a 10 M
Ω
or greater
input impedance, and an accuracy of at least ±1mV.
Zeroing the Sensor
Turn on the Snifit and allow the voltmeter reading to
stabilize – approximately 30 seconds. Then with the
instrument sampling fresh air (air that is free of CO),
adjust the
Zero Adjust
knob at the top of the instru-
ment for a voltmeter reading of 0 ±1 mV.
If you’re not sure about the quality of the surrounding
air, you can apply a blend of Oxygen/Nitrogen gas to
the sensor as described under Calibration.
Checking for CO
Important! Ensure that the sensor grille at the rear of
the instrument is unobstructed and open to the atmo-
sphere. A quick instrument check can be performed by
allowing the smoke of a blown-out match to enter into
the sensor grille. This should cause the indicated CO
level to increase.
After the Snifit has been connected to a voltmeter and
zeroed, simply hold the instrument in the area that
you suspect the presence of CO gas. If CO is present,
the voltmeter will indicate the concentration of CO in
1 mV per ppm. For example: a voltmeter reading of
150 mV indicates a CO concentration of 150 ppm.
Battery Check
For accurate CO readings, pressing the
Batt Test
button must cause the
Batt Test OK
LED to light. If
this LED does not light, replace the battery as
described under Battery Installation.
