8-46 Qualitek mR Owner’s Guide
Test:
The Comp Value and Cal Value can be seen (and edited) on the Leak Calibration
Menu.
The concept previously known to many as the “comp/cal ratio” is employed in the
Qualitek mR as the Pneumatic Signal/Noise Ratio (PSN ratio). Like the Comp Value
and Cal Value, the PSN ratio appears on the Calibration screen.
8.14.2.1 Pneumatic Signal/Noise Ratio
The larger the PSN Ratio, which is the calibration value divided by the compensation
value, the more repeatable the test will be. The PSN Ratio can be as small as 0.5 if
±10% test repeatability is sufficient. The screen suggests ideal values.
So for pressure decay tests, the following rules are strongly recommended:
Comp Value less than or equal to 3 times the Cal value
PSN Ratio (Cal / Comp) ≥ 0.2
Cal Value ≥ 0.05% of full scale of the sensor
For PSN Ratio, the larger the better. Longer test times typically yield a larger PSN
Ratio.
If the Comp Value is set to zero, the PSN Ratio will cannot be computed.
Leak
EndMeasure
test
Tare
test
– Comp–()
Cal
-----------------------------------------------------------------------------------------------------
CalRate×=
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