How to Use the Zero Function
The ZERO-button is one of the most important buttons on a leak detector, yet many operators are hesitant to use it fearing that if they do, they may miss a small leak rate signal that appears suddenly.
Activating ZERO means the processor will keep the ongoing leak rate "in mind" and subtract it from further measured data. This enables the operator to switch the leak detector into a more sensitive range and more easily find smaller leaks. ZERO-function is very effective when an interfering background signal is present, e.g., sniffer leak detection with a helium background of 5ppm in ambient air. If the background signal is unstable, it is important to press the ZERO-button immediately before you approach the probe tip to the assumed leak area.
The Protec P3000 measures the helium concentration of the sniffed air. The ZERO-function of the Protec P3000 is meant to suppress a false signal due to high helium background levels. If the helium concentration at the measuring site is rising, Protec P3000 will show this rising background as a rising leak rate. If the operator is sure that the sniffing probe is not close (say 10 cm) to a leak, the ZERO button can be pressed. This will set the currently measured helium concentration as the reference value. All rising helium concentrations (e.g., due to a leak) will be compared with this reference helium level. This works very well at stable background levels.
If the background helium concentration falls below the reference, a "negative leak rate" is noted which is obviously not correct. Therefore, if the measured helium concentration is below the reference for more than 5 seconds, Protec P3000 will auto zero and the currently measured helium concentration becomes the new reference.
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