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"iL,' `.''. <br /> x-��i'iit"« 'Fs^ :a,, .r�'3 s"-r �_.rer-,mac- `' V" "001di.. �... s,.:.'." <br /> I <br /> GROUIZDWATER TECHNOLOGY <br /> r` STANDARD OPERATING PROCEDURE <br /> CONCERNING OPERATION/CALIBRATION OF <br /> PHOTO-TONIZN.rZON ANALYZER <br /> SOP 14 <br /> The HNU Model 101 Photo-ionization Analyzer shall be used to <br /> measure the concentration of trace gases over a range of <br /> less than 1 part per million (ppm) to .1 gem by <br /> employing the principle of photo-ionization for detection. <br /> The specific instrument used for investigations related to <br /> hydrocarbon contamination should be calibrated for direct <br /> readings in ppm volume/volume of benzene. This portable <br /> field analyzer consists of two components: 1) probe which <br /> contains a fan for moving air into the sensor, an ultra- <br /> violet light (provides ionization energy) , an ionization <br /> chamber and signal amplifier; 2) readout assembly which <br /> contains a battery, ion chamber bias, meter-,readout and <br /> control panel. Specifics of the detection principle/theory <br /> and functions of various components can be found in the <br /> manufacture's instruction manual (Mry Systems, Inc.) . <br /> To assure optimum performance, the photo-ionization analyzer <br /> should be calibrated with a standard gas mixture of known <br /> concentration from a pressurized container. A daily <br /> procedure for calibration involves bringing the probe and <br /> _ readout in close proximity to the calibration gas, cracking <br /> the valve on the tank and checking the instrumen . "eadina• <br /> -' This provides a useful spot check for the instrument. <br /> f A procedure conducted weekly for more accurate calibration <br /> of the instrument from a pressurized container is to connect <br /> one side of a "'I'll to the pressurized container of calibra <br /> tion gas, another side of the "T" to a rotameter and the <br /> third side of the "T" directly to the 8-inch extension to <br /> the photo-ionization probe. Crack the valve of the <br /> pressurized container until a slight flow is indicated on <br /> the rotameter. The instrument draws in the volume of sample <br /> ' required .for detection, and the flow in the rotameter <br /> indicates an excess of sample. Now adjust the span pot so <br /> that the instrument is reading the exact value of the <br /> calibration gas. (If the instrument span setting is <br /> changed, the instrument should be turned back to the standb} <br /> P osition -and the electronic zero should be readjusted, if <br /> necessary) . <br /> __—�, CRoUND RATER <br />