An infrared point sensor or point infrared (IR) detector is a type
gas detector
A gas detector is a device that detects the presence of gases in a volume of space, often as part of a safety system. A gas detector can sound an alarm to operators in the area where the leak is occurring, giving them the opportunity to leave. Th ...
that uses infrared absorption at specific wavelengths to detect changes in gas composition in air.
Gases that can be detected include hydrocarbons, allowing infrared point detectors to be used in safety applications to detect the presence of flammable gases at low levels and shut down equipment as needed to prevent fire or explosion.
Principle
Dual source and
dual receivers are used for self compensation of changes in alignment, light source intensity and component efficiency. The transmitted beams from two
infrared
Infrared (IR; sometimes called infrared light) is electromagnetic radiation (EMR) with wavelengths longer than that of visible light but shorter than microwaves. The infrared spectral band begins with the waves that are just longer than those ...
sources are superimposed onto an internal
beam splitter
A beam splitter or beamsplitter is an optical instrument, optical device that splits a beam of light into a transmitted and a reflected beam. It is a crucial part of many optical experimental and measurement systems, such as Interferometry, int ...
. 50% of the overlapping sample and reference signal is passed through the gas measuring path and reflected back onto the measuring detector. The presence of combustible
gas
Gas is a state of matter that has neither a fixed volume nor a fixed shape and is a compressible fluid. A ''pure gas'' is made up of individual atoms (e.g. a noble gas like neon) or molecules of either a single type of atom ( elements such as ...
will reduce the intensity of the sample beam and not the
reference beam, with the difference between these two signals being proportional to the concentration of gas present in the measuring path. The other 50% of the overlapped signal passes through the beam splitter and onto the
compensation detector. The compensation detector monitors the intensity of the two infrared sources and automatically compensates for any long term drift.
Mean time between failures may go up to 15 years.
Micro heaters
Micro
heaters
A heater is an appliance whose purpose is to generate heat for a building.
Heater or Heaters may also refer to:
Science, technology and engineering
* Central heating, a system used to heat an entire building
Devices
* Aquarium heater, in fishkee ...
can be used to raise the temperature from optical surfaces above ambient to enhance performance and to prevent condensation on the optical surfaces.
Range
Toxic
Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a subst ...
gases are measured in the low parts per million (
ppm) range. Flammable gases are measured in the 0 - 100%
lower flammable limit (LFL) or
lower explosive limit (LEL) range.
See also
*
List of sensors
*
Maintenance-free operating period
*
Service life
A product's service life is its period of use in service. Several related terms describe more precisely a product's life, from the point of manufacture, storage, and distribution, and eventual use.
Service life has been defined as "a product' ...
*
ATEX directive
The ATEX directives are two of the EU directives describing the minimum safety requirements for workplaces and equipment used in explosive atmospheres. The name is an initialization of the term ''ATmosphères EXplosives'' ( French for "exp ...
II 1G EEx ia IIC T6
*
Infrared gas analyzer - for gas monitoring and analysis, rather than leak detection.
References
{{Reflist
Gas sensors