PROGRAMMING OF VRAE4 - 174.4.5 Change LEL/VOL Span GasThis function allows the user to select a specific LEL and/orVOL gas to be used as the span gas during LEL/VOL gascalibration. The LEL and VOL gases must be the same. Forthe LEL mode, setting this gas lets the unit apply the propercorrection factor when calibrating to methane. ForAutorange mode, it also sets the cross-over concentrationwhere the unit switches from 100% LEL to thecorresponding volume % reading. Finally, it selects theproper firmware linearization algorithm for different gases.1. “Change LEL Span Gas?” is the next sub-menu item inTable 4.3.2. Press [Y/+] key. If a LEL sensor is installed or acombination LEL/VOL sensor is installed and the sensoris set to LEL mode, the display shows :LEL Span=?MethaneIf in VOL mode, the display shows “Vol span = ?Methane”. If no LEL/VOL sensor is installed, themessage “No LEL installed“ will appear.3. If the user does not want to change the LEL or VOL spangas, press [Y/+] key to accept the current selection andexit this sub-menu.4. If the user wants to select a different LEL or VOL spangas, press [N/-]. Then use [Y/+] or [N/-] to scrollthrough a list of gas names until a desired gas nameappears in the display; then press [MODE] to select thenew gas name.
