Q. How often should the unit be re-zeroed?

A. Upon receipt of the UV-106, you should rezero the unit so it is set properly for your location.

The electronic zero of the instrument may be measured by attaching an ozone destruction cartridge to the air inlet for a period of 5-10 minutes. For an accurate measurement, the instrument must have been turned on long enough for the internal temperature to stabilize. The observed offset, which can amount to ± a few ppb, can be corrected for by changing this calibration parameter from the front panel, as described below.

Because of noise and/or an inherent offset, some measured values will be below zero at very low ozone mixing ratios or while zeroing the instrument with an external scrubber. Also, the instrument zero may drift by a few ppb over time. For this reason, frequent zeroing of the instrument using an external ozone scrubber to determine the offset is recommended.

If the instrument reads an average of 3 ppb with the external scrubber in place, the value of Z should be set to –3.

Q. What type of serial (RS-232) cable do I need to connect my UV Analyzer to my computer\'s serial port?

A. For a serial connection, you will need a straight-through cable with female-to-female DB-9 connectors.