Edwards ELD500 Series

D135-10-880C - Operation
Page 40
Figure 13 Zero activation
Figure 14 Undo zero
ZERO button Pushing the ZERO button Figure 12 item 11 enables the zero
mode (see Filter and background).
When pressing ZERO the currently measured leak rate is
taken as a background signal and is subtracted from all
further measurements. As a result the displayed leak rate
then is
1 x 10
-8
mbar l/s in GROSS
1 x 10
-12
mbar l/s in FINE
After pressing ZERO (Figure 13, t=1) the decreasing
background is fitted to the course (Figure 13, t=2)
automatically. When the measurement signal declines below
the saved background the underground value will
automatically be equated with the measurement signal. As
soon as the measurement signal is increasing again the saved
decreasing value remains constant. Increasing of the signal
are displayed clearly as a leak So it is possible to recognize
leaks even when the signal is decreasing rapidly.