Varian 990 dCLD II, Operation Manual

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Model 990 dCLD II Component Leak Detector
3-24
3.7.2 Conversion of 2 V/Dec Log to Leak Rate if 10 X Function Not Available
To read leak rates in all four decades of the 990 dCLD II using the analog leak rate output
voltage, it is recommended that the 2 V/Decade Log format be used. Use the following
method to obtain the leak rate from the 2 V/Decade Log format if a 10
x
function is not avail-
able in the host computer or PLC.
The leak rate is split into two integers; the first integer is the exponent of the leak rate, the
second integer is the mantissa of the leak rate.
Exponent = INT (Vout /2) - | RANGE variable | + 3
Where: INT ( ) is the integer part of the expression
Vout is the analog leak rate output voltage
RANGE variable is the RANGE number from the ?SETUP<CR> command or viewed through
the touch screen panel menu
| | is the absolute value of the expression inside the bars (change the sign to + if it is -)
Mantissa = 1 + Y·(1 + Y/2·(1 + Y/3·(1 + Y/4·(1 + Y/5·(1 + Y/6·(1 + Y/7)))))
Where:Y = 2.302259·(Vout / 2 - INT (Vout / 2))
INT ( ) is the integer part of the expression in parentheses
3.8 Shutdown
Shutting down the 990 dCLD II is as simple as turning the power off by moving the power
switch on the rear panel to the
°
position. The system can be in any mode when it is shut
down. When the system is shut down, all valves controlled by the system close. Also, if the
PLC has asserted PARALLEL ENABLE when the system is shut down, it remains asserted and
control remains with the PLC when it is turned back on.