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ProductsLaserGasTM I Monitors
Introduced to the market in 1995 and installed in more than 1000 units worldwide, the LaserGas I monitors have paved the way for fast and reliable in-situ process control and precise continuous emission monitoring. It was the first generation of gas monitors to employ tuneable diode laser (TDLAS) technology and a measurement principle known as 'single line spectroscopy', which eliminates cross interference from other gases and enables very low concentrations of gas to be detected (see Technology for more information). LaserGas I monitors are available in the following configurations:
LaserGasTM I Single Path MonitorSingle Path monitors are designed for in-situ measurement with path lengths in the range 0.5 - 15 m (pipes, stacks, ducts). This model operates over the range 2 - 3 bar maximum pressure and temperatures up to 500ºC, but it is possible to operate at up to 20 bar and 1500ºC with some gases (see LaserGas II SP Table of Gases).Features
The monitor consists of 3 modules, a transmitter and receiver unit plus the electronics unit with display. Measurement readings are provided through standard 4-20mA current loops or an optional fibre-optic output. TÜV approval for HCl emission monitoring was accomplished in February 2000 (see also the listing on the homepage of the German Environment Ministry http://www.umweltbundesamt.de/messeinrichtungen/moemi4.pdf ). MCERTS approval was awarded in 2006 (see http://www.neomonitors.com/news for more details).
Measuring principleA single gas absorption line with no interference is chosen in the near IR spectral range and scanned by a single-mode diode laser. A detector located opposite the laser detects the light absorption caused by the target gas molecules, after which the gas concentration is calculated. Automatic correction for temperature, pressure, and dust load variations is included (see Technology for more information).
Installation and OperationThe LaserGas I SP monitor is easy to install and designed to operate in very rough industrial environments. The transmitter and receiver units are mounted directly onto the stack flanges. They are easily aligned and maintained, and cleaning of the window may be done without realignment. To prevent dust and other contaminants from settling on the optical windows, these should be purged with dry and oil free pressurised air, or by a fan. During start up and calibration of the monitor a PC running the LaserGas service software must be connected to the monitor electronics unit.The rugged industrial design makes the monitor easy to maintain. There are no moving parts in the instrument and no consumables are needed during operation of the instrument. All critical instrument parameters are monitored continuously and warning messages are displayed should maintenance be required. Calibration checks are recommended every 6 - 12 months.
Data sheet for down loadLaserGas I HCl Monitor (PDF, 24512 bytes)
LaserGasTM I Dual Path MonitorThe Dual Path monitor is designed for in-situ measurements with path lengths in the range 0.5 - 15 m (pipes, stacks, ducts). Pressure and temperature ranges and available gases are as for the Single Path monitor (see LaserGas II SP Table of Gases). The Dual Path monitor includes the additional feature of automatic zero and span check, which is a requirement for certain emission monitoring applications.
Features
Measuring principleA single gas absorption line with no interference is chosen in the near IR spectral range and scanned by a single-mode diode laser. A retro-reflector located opposite to the laser reflects the light back to the transceiver. A detector collects the returned light for further analysis and calculation of the gas concentration (see Technology for more information).
Installation and OperationThe LaserGas I DP monitor is easy to install and designed to operate in very rough industrial environments. The transceiver and retro-reflector units are mounted directly onto the duct or stack flanges. Preventive maintenance is limited to visual inspection and cleaning of optical windows. Purging with instrument air or nitrogen prevents dust from fouling the optical windows. Calibration checks are recommended every 6 - 12 months.
Zero and Span Check OperationThe transceiver unit includes a stepper motor and rotating wheel, which enable zero and span checks. The wheel has three possible positions (see figure below):
During normal operation the laser beam is sent past the rotating wheel, through the process gas and reflected back by the retroreflector located at the opposite side of the stack. During zero check operation the rotating wheel inserts a retroreflector into the laser beam internally in the transceiver unit. The laser beam is therefore reflected back to the detector without entering the process gas; thus a zero measurement is enabled assuming no gas (the gas to be measured) is present inside the transceiver unit. During span check operation the rotating wheel inserts a retroreflector and a pre-calibrated span gas cell containing the gas to be measured into the laser beam internally in the transceiver unit. The laser beam is therefore reflected back to the detector passing through the span gas cell without entering the process gas; thus a span measurement is enabled. The span level is adjustable, but set to a fixed value during production.
NEO Monitors is a subsidiary of Norsk Elektro Optikk A/S
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