Lub hauv paus ntsiab lus ntawm cov tshuaj lom thiab teeb meem roj ntes
Raws li kev phom sij, peb faib cov pa phem thiab cov pa phem rau hauv ob pawg: cov pa hluav taws xob thiab cov pa phem. Vim lawv cov khoom sib txawv thiab kev phom sij, lawv txoj kev tshawb nrhiav kuj sib txawv.
Combustible gases yog cov pa phem tshaj plaws uas tau ntsib nyob rau hauv kev lag luam chaw xws li petrochemicals, feem ntau organic gases xws li alkanes thiab tej yam inorganic gases xws li carbon monoxide. Kev tawg ntawm combustible gases yuav tsum tau raws li tej yam kev mob, xws li: ib tug tej yam concentration ntawm combustible gases, ib tug npaum li cas ntawm cov pa oxygen, thiab txaus tshav kub rau ignite lawv ignition qhov chaw. Cov no yog peb lub ntsiab lus tseem ceeb ntawm kev tawg, tsis muaj ib qho uas yuav tsum tau ua. Hauv lwm lo lus, tsis muaj ib qho ntawm cov xwm txheej no, hluav taws kub thiab tawg yuav tsis tshwm sim. Thaum cov roj hluav taws xob (steam, plua plav) thiab cov pa oxygen sib xyaw thiab ncav cuag ib qho concentration, qhov tawg yuav tshwm sim thaum ntsib qhov hluav taws kub nrog qee qhov kub. Peb xa mus rau qhov concentration ntawm combustible gases uas tuaj yeem tawg thaum lawv los rau hauv kev sib cuag nrog qhov hluav taws kub raws li qhov tawg concentration txwv, abbreviated li qhov tawg txwv, uas yog feem ntau qhia nyob rau hauv%. Qhov tseeb, qhov sib xyaw no tsis tas yuav tawg hauv qhov sib xyaw ua ke thiab yuav tsum muaj qhov sib txawv. Thaum lub concentration ntawm cov roj combustible qis dua LEL (* tsawg tawg txwv) (tsis txaus combustible gas concentration) thiab thaum nws concentration siab tshaj UEL (* siab tawg txwv) (tsis txaus oxygen), tsis muaj tawg yuav tshwm sim. LEL thiab UEL ntawm cov roj hluav taws xob sib txawv sib txawv (saib cov lus qhia hauv qhov teeb meem thib yim),
Qhov no yuav tsum tau ua tiag tiag thaum calibrating lub ntsuas. Rau lub hom phiaj ntawm, peb yuav tsum feem ntau tshaj tawm lub tswb thaum cov roj combustible concentration yog 10% thiab 20% ntawm LEL, qhov twg 10% LEL raug xa mus rau. Ua qhov ceeb toom ceeb toom, thiab 20% LEL hu ua kev ceeb toom txaus ntshai. Tias yog vim li cas peb thiaj li xa mus rau cov khoom siv hluav taws xob hluav taws xob li LEL detectors.
Nws yuav tsum tau muab sau tseg tias, 100% tso tawm nyob rau hauv lub LEL detector tsis yog hais tias cov concentration ntawm combustible gas ncav cuag 100% ntawm cov roj ntim, tab sis hais tias nws mus txog 100% ntawm LEL, uas yog sib npaug rau qhov tsawg combustible txwv ntawm combustible. gas. Yog tias nws yog methane, 100% LEL=4% ntim concentration (VOL). Hauv kev ua haujlwm, tus ntes uas ntsuas cov pa roj hauv ib qho LEL yog ib qho khoom siv catalytic combustion detector. Nws lub hauv paus ntsiab lus yog tus choj dual (feem ntau hu ua Wheatstone choj) nrhiav kom pom. Ib qho ntawm cov platinum hlau txuas hniav no yog coated nrog cov tshuaj catalytic combustion. Txawm hais tias cov roj hluav taws xob tsis zoo, tsuav nws tuaj yeem raug hluav taws xob los ntawm electrode, qhov kev tiv thaiv ntawm platinum hlau choj yuav hloov vim qhov kub thiab txias. Qhov kev hloov pauv tsis haum no yog proportional rau qhov concentration ntawm cov pa taws. Qhov concentration ntawm cov roj hluav taws xob tuaj yeem suav tau los ntawm qhov ntsuas qhov ntsuas hluav taws xob thiab microprocessor. Lub thermal conductivity VOL detector uas ncaj qha ntsuas lub ntim concentration ntawm combustible gases kuj muaj nyob rau hauv kev ua lag luam, thiab twb muaj detectors uas ua ke LEL / VOL. VOL combustible detectors yog tshwj xeeb tshaj yog haum rau ntsuas combustibles nyob rau hauv ib puag ncig tsis muaj oxygen.
