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ADVANCED OPTICAL DESIGN INCREASES RELIABILITY The OPAC20/20 double pass opacity monitor uses a green light emitting diode (LED) light source. The low powered solid state light source emits negligible heat and is electronically modulated, eliminating chopping mechanisms and their inherent problems. High frequency modulation creates a more stable opacity response and eliminates the ambient light interference found in low frequency modulation of incandescent lamp opacity monitors. The long life of LED's , creates a trouble free optics assembly. The OPAC20/20 opacity monitors' LED has an expected life of ten years.
System alignment is performed using a direct view alignment port built into the light source optics. The retro reflector also contains a built in alignment port, to align the retro reflector. Alignment of both opacity monitor light source and reflector is critical for accurate off stack zeroing of opacity monitors. Electronic alignment monitoring makes the OPAC20/20 the only opacity system that continually tracks its cross stack alignment, and notifies the operator if system misalignment reaches a critical point, effecting opacity readings. Purge plenums with automatic, integral shutters, protects the transmissometer and reflector optics from stack effluent, in the event of a loss of sufficient air purge.
POWERFUL REMOTE CONTROL UNIT The microcomputer, menu driven remote control unit, is the most powerful interface available. Software allows for advanced trouble shooting, calibration control, and opacity system customization. Historical opacity calibration, opacity alarms, PLCF changes, and operational parameters are maintained in viewable logs that can be output via the systems built in RS232 interface.
ELECTRONIC STACK CONTROLS ELIMINATE CALIBRATION ERRORS A junction box in the transmissometer weather enclosure, provides an opacity readout and control switches for maintenance and calibrations. The opacity signal comes from the control unit and is (PLCF) corrected and corresponds directly with the control unit opacity readout. The transmissometer contains all stack electronics and has no manual adjustments inside the transmissometer. All calibration functions are performed electronically by the control unit software. The sealed light source never needs to be opened for any system calibration functions.
CONTINUOUS STACK SAMPLING Unlike continuous wheel calibration schemes that stack sample 20 percent of the time, the OPAC20/20s' continuous stack sampling gives you unbeatable instrument response. The faster, more thorough stack sampling, enables better combustion control, identification of potential emission control problems, and improved low range opacity detection. Zero and span calibrations are performed hourly and timed for continuous stack sampling with no monitor down time. Calibration drift is automatically compensated for and we report the information daily on user selected outputs. The hourly system calibrations assure minimal erroneous data collection. Dirty window compensation is corrected hourly and we display a visual alarm on the operator panel if the correction limit is exceeded. © Phoenix instruments Inc. 1999
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