How The Detectors Work - General RLD440 User Manual

HOW THE DETECTORS WORK

The UV leak detection system works as follows. After charging the A/C system with
fluorescent dye, the technician scans the system's components with UV light from three
LEDs mounted on the end of the instrument's grip. Any dye escaping from the system
will glow a bright yellow-green.
Following are the details of the electronic leak detection system. A small mechanical
pump inside the RLD440 draws a sample of air through the tip of the instrument's 17-in.
long probe into a proprietary sensor 1-1/2 inches downstream. A proportional halogen
detector in the sensor determines whether any refrigerant gas is in the sample. If any
gas is detected, the sensor and other circuits measure the amount of refrigerant and
convert the value to an electrical signal.
If no leak is detected, no signal is produced and the display remains off (dark). When a
leak is detected, the signal is amplified, digitized, and displayed on the front panel as a
large, bright red number from 1 to 9 corresponding to the size of the leak (1 for the
smallest leaks, 9 for the largest).
The digital readout makes it easy to pinpoint the source of a leak and helps you decide
whether it is large enough to be worth plugging. The reading is independent of the
selected sensitivity level (three are available) and is at its highest when the tip of the
probe is at the source of the leak. A table in the Operating Instructions section of this
manual correlates display readings with leak size, in ounces per year.
The RLD440's electronic detection system also uses sound to help locate the source of a
leak. Whenever the unit is on, it continuously produces three very loud beeps every two
seconds. When a leak is detected, the frequency of the beeping increases dramatically.
The beeper can be muted by pressing a dedicated button on the front panel.
A third feature of the electronic system that helps locate leaks is a red LED adjacent to
the sensor at the end of the probe. This light flashes in sync with the beep. In other
words, it flashes three times every two seconds whenever the unit is on, and much
faster whenever the unit detects refrigerant. When the red LED begins to flash rapidly,
your eye will naturally be drawn to it—and therefore the location of the leak. Like the
leak-size readout, the LED at the end of the probe is bright enough to be visible in full
sunlight.
The RLD440 automatically compensates for ambient levels of refrigerant gas. No
manual sensitivity adjustments or power adjustments are required.
The instrument is supplied with a proprietary leak test vial that lets you verify that it is
working properly prior to searching for a leak. The RLD440 is powered by four "AA"
batteries, which are included in the case.
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