4
If a check is to be made for trace amounts of gas in a bar hole or above ground, for
example around the foundation of a structure, the % GAS or % LEL display should be used. The
bar holing feature using the RESET switch is appropriate for pinpointing underground leaks.
To Use the % LEL Scale.
Connect an appropriate probe to the water-block filter
attached to the hose and turn selector switch to position marked "% LEL". The display shows
"LEL"
for about 15 seconds.
*
After warm-up, the concentration of natural gas in air is displayed as percent of the
lower flammable limit (LEL). If the air is clean (contains no gas), the display should
read zero. If it does not, switch to position marked "AUTO ZERO". After the display
shows
"End"
, return the switch to the % LEL position.
*
The % LEL scale ranges from 0 to 100 % in steps of 1%. The following table shows
equivalent readings in % LEL and % GAS (percent volume):
EQUIVALENT READINGS IN % LEL AND % GAS
% LEL
% GAS
0.6
equivalent to
0.03
1
0.05
2
0.1
10
0.5
20
1.0
100
5.0
To Detect Gas and Track Its Source with the TRACK GAS Display.
Connect an
appropriate probe to the water-block filter attached to the hose and turn selector switch to
position marked "TRACK GAS". The display shows
"SniF"
(sniff) for about 25 seconds.
*
After warm-up, the display shows the concentration of gas in air in % LEL with the
RGI-201, RGC-301, RGO-321, RGA-411 and RGA-611 and % GAS with the RGI-
211, RGC-311, RGA-412 and RGA-612. If the air is clean (contains no gas), the
display should read zero. If it does not, switch to position marked "AUTO ZERO".
After automatic adjustment of zero is complete, return the switch to the "TRACK
GAS" position.
•
Advance a probe along the pipe or other conduit suspected of having a gas leak. The
beeper will sound once every 2 seconds at 0.2% LEL (0.04% GAS) concentrations of
gas, will speed up with rising concentration, and will beep continuously at 2% LEL
(0.1% GAS) above ambient (no beep at or below 0.1% LEL). By listening to the
beeper or by reading the display, the source of gas can be located.
•
If, during leak tracking, the background concentration of gas rises above zero, the
display and beeper can be reset to zero by pressing the RESET switch on the front
panel. Resetting or suppression of the zero for background gas can be carried out up
to 3% LEL (0.15% GAS); above this level, the instrument will not reset the zero.
•
Sometimes it is desirable to silence the beeper during a leak survey. To silence the
beeper, first place the selector switch in the % GAS position, then press and hold the
RESET switch on the front panel while turning the selector switch from % GAS to
