990 CLD Autoline™ Leak Detector
DR
AFT 2/2/04
2-5
Leak Rate Output Voltage Selection
The leak rate output voltage, on the 990 CLD leak detector rear panel, can be configured to
vary linearly or logarithmically with the measured leak rate. For a logarithmic output format,
either a 2 V/decade or 3 V/decade sensitivity is available (Figure 2-1).
NOTE
For logarithmic output, the shorting plugs shown in Figure 3-1
on page 3-14 must be in position A-1. Both shorting plugs
shown in Figure 2-1 and Figure 3-1 must be in these positions
at all times.
Refer to Appendix A “Understanding the 990 CLD Analog Leak Rate Output” for a
discussion on choosing the best leak rate output format for a specific application. The
accompanying graphs may aid in the conversion from output voltage to leak rate and vice
versa.
The factory-set linear output voltage ranges from 0 V for a zero leak rate on the most
sensitive scale to 10 V at full scale on the least sensitive scale. When the UNDER LED is lit
on the Least Sensitive scale, the output voltage maximum is +10.7 V.
Figure 2-1
Leak Rate Output Voltage Selection
The logarithmic output voltage for the 2 V/decade choice ranges from near zero for a zero
leak rate on the most sensitive scale to 8 V at full scale on the least sensitive scale. If the:
❑
UNDER LED is lit, the output voltage minimum is
−
0.2 V.
❑
OVER LED is lit when on the Least Sensitive scale, the output voltage maximum
is 10.7 V.
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