Veeco MS40 Operation And Maintenance Manual page 22

ZERO
SNIFF MODE INDICATOR
START
Vacuu VI m Instrument Corp. C Leak Detection
2099 Ninth Avenue 2099 Ninth Avenue
Ronkonkoma, NY 11779 Ronkonkoma, NY 11779
631.737.0900 631.737.0900
1109-186-00 Rev. C
In Standard Mode, The ZERO momentary switch is active
only during actual leak testing. When pressed, this unit's
computer reduces the measured leak rate displayed by the unit.
To zero within the decade being measured (e.g., a 4 x 10
cc/sec leak rate would now be displayed as a 0 x 10
cc/sec leak rate). This function is usually used when
background helium causes measurement problems during
testing. Note that this function also limits the maximum
sensitivity of testing to two decades (or ranges) below the
zeroed decade.
When the unit is in Service Mode, pressing the ZERO
momentary switch will toggle the turbo-molecular pump on or
off. When the ZERO LED indicator is lit, the turbo-molecular
pump is on.
When lit, the unit has been placed in the Sniff Mode. When
in Standard Mode, the unit is placed in the Sniff Mode by
pressing the SNIFF valve momentary switch located on the
left of the Service Panel. When the unit has been placed in
Service Mode, pressing the SNIFF valve momentary switch
opens the Sniffer Valve.
WARNING
Never operate the MS-40 in Sniff Mode without the optional
Sniffer Assembly or without the standard plug in place on the
Sniffer Quick Connect Fitting (QCF). Running the unit without
covering the Sniffer QCF will cause a dramatic increase in fore-line
pressure within the unit, and will thereby cause the unit's turbo-
molecular pump to rapidly shut down.
Pressing this pushbutton begins a test cycle. During testing,
pressing the START pushbutton again will halt all testing by
closing all vacuum system valves (except the fore-line valve).
This also places the unit into its standby (wait) mode.
Pressing the START pushbutton instead of the VENT
pushbutton eliminates the chance of the user inadvertently
venting the system (refer to the VENT function, below).
The START pushbutton lights when a test cycle has been initiated.
-6
std
2-5
-6
std