Varian 990 dCLD II, Руководство по эксплуатации

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Model 990 dCLD II Component Leak Detector
3-8
TURBO SPEED Set the speed of the high vacuum pump to FAST or SLOW, depend-
ing on the sensitivity requirement of the system. (Refer to Table 2-1
on page 2-2.) Note that the highest tolerable testing pressure is
achieved with the pump running in the high-speed (fast) mode.
To set the turbo speed, issue the INIT-SPEED<CR> command or, if
the optional front control panel is installed, set the turbo speed via
the Leak Rate Ranging Set-Up screen (see Section 4.6.4 “Range
Stop and Manual Range Set Up and Control” on page 4-15).
RANGE Range must be set equal to the exponent of the least sensitive range
of the leak detector (Section 3.2 “System Sensitivity and Configura-
tion” on page 3-6), depending on the sensitivity of the vacuum sys-
tem. (See “TOP RANGE”.)
To set the RANGE variable, issue the INIT-RANGE<CR> command.
TOP RANGE TOP RANGE is the exponent value of the least sensitive range of
leak detection for the configured system. The system detects four
decades starting from the TOP RANGE. The TOP RANGE variable
must be set appropriately for the given system configuration and is
the largest exponent value. See Table 3-1 on page 3-6.
To set the TOP RANGE, issue the INIT-RANGE<CR> command, or
if the optional front control panel is installed, set the parameter via
the Leak Rate Ranging Set-Up screen (see Section 4.6.4 “Range
Stop and Manual Range Set Up and Control” on page 4-15).
AUTO-RANGE
MANUAL RANGE Auto-Ranging causes the leak detector to detect leaks within the
four decades starting at the least sensitive value set in the RANGE
variable (RS-232) or TOP RANGE (optional front control panel).
The 990 dCLD II is shipped from the factory with Auto-Ranging
enabled set as the default.
Manual Range is used to force the 990 dCLD II to respond to a leak
rate detected in only one decade (the exponent never changes).
This feature is useful when the test operator is only concerned with
monitoring the leak rate measurement within a single decade. You
must set Manual Range ON and also set the EXPONENT variable
(see “MANUAL EXPONENT” below) to the desired decade.
Regardless of the ranging mode selected, the RANGE variable
(above) must be set to the least sensitive decade.
To set Manual Range ON, issue the MANUAL<CR> command or, if
the optional front control panel is installed, turn Manual Range ON
via the Leak Rate Ranging Set-Up screen (see Section 4.6.4 “Range
Stop and Manual Range Set Up and Control” on page 4-15).