Inficon 510-010, Technical Handbook

Page: 21 / 52

Principle of Operation
2-1
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2 Principle of Operation
2.1 Description
The HLD5000 is capable of detecting, measuring and displaying quantitatively the
refrigerant, C0
2
or SF
6
sucked in through the probe’s line by means of its infrared gas
analyzer.
The important subassemblies of the HLD5000 are:
• the sensor system subassembly located in the probe
• the pump system together with the electric and electronic subassemblies
accommodated in the main unit
Infrared light from a corresponding source is made to pass through a cell through
which also the gas taken in by the HLD5000 flows. This light is filtered so that only
light having a specific wavelength is allowed to pass on to an infrared light detector.
If in the presence of a leak, refrigerant, SF
6
or CO
2
enters with the air taken into the
cell, the infrared light is partly absorbed by the refrigerant. The intensity of the light
arriving at the detector is thus reduced.
The change in the intensity of the light is amplified electronically, converted from
analogue to digital and is displayed visually and audibly after processing by the
microprocessor in the main unit. By means of a reference measurement based on
the ambient air, the background concentration of the test gas or other interfering
gases is taken into account when processing the measured data.
Fig. 2-1 Flow of the gas within the HLD5000