INFICON UL5000 Dry Helium Leak Detector - Manual (Page 8)

8
General Information
iina
74
e 0
1
.f
m
te
chn
ica
l ha
nd
boo
k
(1
40
8)
Auto zero
Determination and automatic adaptation of the helium background.
Through this function, the internal zero level of the instrument is determined which is
then subtracted from the current leak rate signal. This function is run during the cali-
bration process or when operating the start pushbutton, provided the UL5000 has
been running previously for at least 20 seconds in the standby or vent mode. If the
helium background previously suppressed should drop so that for the duration of the
zero time only the display limit will be displayed, the zero level is adapted automati-
cally.
Menu
The menu allows the user to program the UL5000 according to his requirements. The
menu has a tree architecture.
Default
Status of the UL5000 when supplied by the factory.
GROSS
GROSS is a measurement mode which allows high inlet pressure (1 to 15 mbar).
The smallest detectable leak rate is 1×10
-6
mbar l/s.
FINE
FINE is the medium measurement mode with inlet pressure between 2 and 0,4 mbar.
Detection limit is 1×10
-10
mbar l/s.
ULTRA
ULTRA is the most sensitive measuring range with inlet pressures below 0,4 mbar.
The minimum detectable leak rate is < 5×10
-12
mbar l/s.
Foreline pressure
Pressure in the foreline between Turbo pump and scroll pump.
Minimum detectable leak rate
The smallest leak rate the UL5000 is able to detect (
 5E-12 mbar l/s).
Internal helium background
The existing helium partial pressure in the measurement system. The level of the
internal helium background is measured in the Stand-by mode and subtracted from
the measured signal.
Measure Measurement mode
The UL5000 measures the leak rate of the test sample.