SIMRAD GD10P - IR GAS DETECTOR - ICEWeb

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22Refer to Figure 5.2 below.Radiation from two infrared sources passes through two narrowbandfilters selecting a measuring wavelength and a reference wavelength.The sources are electronically chopped. Radiation is divided by abeamsplitter into an internal and external path. The internal path isviewed by the compensation detector, and the external path is viewedby the measuring (main) detector. The compensation detectormonitors and compensates for drift in sources or detectors. The maindetector monitors the external measuring path and detects whether theselected gas is present.The four signals, two from the compensation detector and two from themain detector, are amplified, digitised and fed to the microprocessor.The signals are used by the microprocessor to calculate the gasconcentration. The gas response is then linearized and presented aseither a voltage, a current or a digital output signal. Internal signals arecompared with test limits to monitor electronics and optical parts. Ifvalues outside the test limits are found, specific error messages aregiven.Optical filter characteristics remain constant over time, and drift in theother components is monitored and compensated by the dualwavelength, dual path concept. This means that the zero and gas spanfactory calibration will remain stable regardless of component drift, andthat the detector needs no manual recalibration after factorycalibration.
23Figure 5.2Block diagram, GD10P5.3 Performance characteristics5.3.1 Gas dataThe GD10P standard version is factory calibrated and linearized withmethane gas in the 0-100 % LEL range. Calibration/linearization toother gases or concentrations can also be done.Accurate measurements can only be achieved by having the detectorcalibrated for the gas it is intended to measure.Gases such as ethane, propane and butane are also detected by theGD10P. A GD10P calibrated for methane has a higher sensitivity tothese gases than to methane. This means that explosion danger fromother HC-gases will always be detected by the GD10P.Because of tolerances in the infrared filters, readings of other gasesthan methane will not be exact when the detector is calibrated to 100%LEL methane.
Page 1: SIMRAD GD10P - IR GASDETECTOROPERAT
Page 4 and 5: 5.4 GAS DETECTION SYSTEM...........
Page 6 and 7: 41.2 ConstructionA complete GD10P G
Page 8 and 9: 6- Electrical connection 3 wires (M
Page 10 and 11: 8EN 61779-4/IEC 61779-4EN 50081-1EN
Page 12 and 13: 10In order to achieve minimum respo
Page 14 and 15: 122.1.4 Mounting the GD10PThe detec
Page 16 and 17: 142.2.2.2 Retrofit mountingFor retr
Page 18 and 19: 163. OPERATION3.1 Start-up procedur
Page 20 and 21: 18• If there is an air movement o
Page 22 and 23: 20Figure 4.3Test procedure
Page 26 and 27: 24Converting % LEL to % v/v is base
Page 28: 261 21: Plate Adapter (junctionbox/

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