Low Battery Indicator
Replace the 4 AA Alkaline batteries when the red LED on the
control panel is lit. Follow battery installation instructions under
Maintenance section.
Audio Mute Function
To silence or mute the audio beep and alarm signal, press the
MUTE button. To restore the audio sound, press the MUTE
button again. (Note: a few seconds is required to restore sound
if the mute button is pressed in rapid succession.)
Cross Sensitivity to Automotive Chemicals
Some automotive solvents and chemicals have similar hydrocarbon
properties as H2 and may elicit a positive response (<20 seconds)
from the D740. Before leak checking, clean up any chemicals in the list
below that elicit a positive response.