Ultra-small incandescent lamps with low efficiency coefficient are used as the emission source in standard infrared sensors. Patented and produced by Optosense, LED-type infrared emission sources are used in MIPEX innovative gas sensors. Their efficiency of power transformation into infrared emissions of the required spectrum range of the waves in the mode of ultra-short pulses of LED operation is several times higher. Moreover, the sensors comprise optimized optic scheme, a highly sensitive photodetector (up to 10 times more sensitive than a pyroelectric detector), special algorithms of signals processing and other know-how, providing optimal operation of the sensors at low power consumption.
MIPEX infrared gas sensors have a patented design and spectral measurement circuit, providing minimal impact of moisture on measurement result. The impact of moisture meets the requirements of IEC 60079-29-1. However, it should be mentioned that MIPEX sensors, as any other gas sensor, is sensitive to condensed moisture influencing accuracy of measurements until evaporation of liquid from optical surfaces.
A temperature compensation mechanism is provided in MIPEX infrared gas sensors. At rapid temperature change due to various reaction rates of separate components of the sensor, this mechanism may not work optimally. This is because the sensor is in a status that indicates rapid temperature change and consequently could result in unreliable readings. At rapid temperature change and upon high humidity conditions, condensate formation on the sensor’s optical surfaces is possible. In this case the unreliable reading may occur until the surfaces become dry.
The sensor measures partial pressure. Sensor readings are directly proportional to pressure. For example, at the pressure equal to 1 atm, the sensor readings are 2.0% vol. Thus, when the pressure of the same gas mixture increases to 1.1 atm, the sensor readings will be 2.2% vol.
Calibration of MIPEX infrared gas sensor consists of two stages: zero setting and scale (scale coefficient) setting. Calibration of the sensor is required at primary installation in gas analyzers as well as during preparation for the equipment check.
Zero setting should be performed after long-term storage without power supply, as well as after transportation and filter installation.
Scale setting of MIPEX infrared gas sensor should be performed no more than once in 36 months.
After installation of the filter and installation of the sensor in the equipment, due to additional reflections, the distribution of light stream inside the sensor can be changed, resulting in changing of signals ratio and consequently zero change. Due to the shock impact, changes in optical picture can occur after transportation. By the force of natural processes during the long-term storage, the signals ration in channels can be changed. During sensor operation, such changes are considered by means of zero automatic correction algorithm.
Without application of the dust filter, the sensor optical surfaces may become dirty. If this occurs, the optical channels may become lower than the minimal threshold value. If the gas analyzer is already equipped with the filter, it is not necessary to use the replaceable filter, because installation of the additional filter influences sensor response.
During factory calibration, the sensor memory is filled with the data of polynominal linearization of the points in full range. The polynoms of methane and propane are different from each other. In order to perform sensor re-calibration for other gases, it is necessary to save the data of the corresponding polynom in the sensor memory. User calibration is performed by 2 points which is not sufficient for building of the polynom.