Omntec FuelCheck, Инструкция по установке и эксплуатации

Страница: 5 / 42

4
Principle of Operation
FuelCheck
®
is a totally fiberoptic system for measuring the index of refraction of fluids in petro-
leum pipelines.
The
FuelCheck
®
Controller incorporates an extremely stable fiberoptic light source and detector.
This stability is provided by maintaining the source and detector circuitry at a constant tempera-
ture. Light from the infrared LED light source is coupled into the source fiber of the fiberoptic in-
terconnect cable. The
FuelCheck
®
Probe reflects light from the source fiber to the detector fiber.
Some of the light is refracted into the fluid in which the probe lens is immersed. The amount of
light that is refracted (lost) from the lens is directly proportional to the index of refraction of the
fluid in which the probe lens is immersed. Thus, the higher the fluid’s index of refraction, the less
amount of light is returned to the detector in the
FuelCheck
®
Controller.
5 mm
1. Sensor is a 5 mm diameter
sapphire hemisphere.
2. Optical fibers are very precisely
fused onto the flat side of the lens.
3. An LED is used to provide
constant intensity light to the lens
through either of the fibers. (LED
located in the FuelCheck
Controller, up to 2 km away from
sensor)
4. The inner surface of the lens acts
as a mirror: some of the light
reflects inside the lens; however,
some light refracts out of the lens
into whatever fluid is wetting the
lens. The amount of light lost to
refraction is directly proportional
to the refractive index of the fluid
wetting the lens.
5. Whatever light is not lost to
refraction returns to the
FuelCheck Controller via the other
fiber where its intensity is
precisely measured and converted
to a scaled value.
reflected
light
refracted
light
fiberoptic length
up to 2 km
FuelCheck
FuelCheck Operating Principle
Figure 2
Principle of Operation