Introduction to Combustible Gas Detectors thiab Toxic Gas Detectors
Combustible gases yog cov pa phem uas feem ntau ntsib nyob rau hauv kev lag luam chaw xws li petrochemicals, feem ntau muaj cov organic gases xws li alkanes thiab tej yam inorganic gases xws li carbon monoxide. Kev tawg ntawm cov pa hluav taws xob yuav tsum ua kom tau raws li qee qhov xwm txheej, uas yog: qee qhov kev xav tau ntawm cov pa roj combustible, qee cov pa oxygen, thiab qhov hluav taws kub uas muaj cua sov txaus los hlawv lawv. Cov no yog peb lub ntsiab ntawm kev tawg (raws li qhia hauv daim duab peb sab tawg nyob rau sab laug daim duab saum toj no), tag nrho cov no yog qhov tseem ceeb. Hauv lwm lo lus, qhov tsis muaj ib qho ntawm cov xwm txheej no yuav tsis ua rau hluav taws kub lossis tawg. Thaum cov roj hluav taws xob (steam, plua plav) thiab cov pa oxygen sib xyaw thiab ncav cuag ib qho concentration, lawv yuav tawg thaum raug hluav taws kub nrog qee qhov kub. Peb xa mus rau qhov concentration ntawm cov roj combustible tawg thaum raug hluav taws kub raws li qhov kev txwv ntawm qhov tawg, luv luv li qhov txwv tsis pub tawg, uas feem ntau qhia hauv%. Qhov tseeb, qhov sib xyaw no tsis tas yuav tawg ntawm qhov sib tov sib xyaw thiab yuav tsum muaj qhov sib txawv.
Qhov chaw ntxoov ntxoo qhia hauv daim duab ntawm sab xis saum toj no. Thaum lub concentration ntawm cov roj combustible qis dua LEL (tsawg kawg explosive txwv) (tsis txaus combustible gas concentration) thiab tshaj UEL (qhov siab tshaj plaws tawg txwv) (tsis txaus oxygen), yuav tsis muaj tawg. LEL thiab UEL ntawm cov roj hluav taws xob sib txawv sib txawv (saib cov lus qhia hauv qhov teeb meem thib yim), uas yuav tsum tau coj mus rau hauv tus account thaum ntsuas ntsuas ntsuas. Rau cov laj thawj kev nyab xeeb, feem ntau peb yuav tsum tau tshaj tawm lub tswb thaum lub siab ntawm cov roj hluav taws xob yog nyob ntawm 10% thiab 20% ntawm LEL, qhov twg 10% LEL raug xa mus. Ua kev ceeb toom ceeb toom, thaum 20% LEL hu ua kev ceeb toom txaus ntshai. Yog vim li cas peb hu lub combustible gas detector LEL detector.
Nws yuav tsum tau muab sau tseg tias 100% tso tawm nyob rau hauv lub LEL detector tsis qhia hais tias cov concentration ntawm combustible gas ncav cuag 100% ntawm cov roj ntim, tab sis mus txog 100% ntawm LEL, uas yog sib npaug rau qhov tsawg tshaj plaws tawg txwv ntawm combustible gas. Yog tias nws yog methane, 100% LEL=4% ntim concentration (VOL). Hauv kev ua haujlwm, lub ntsuas ntsuas uas ntsuas cov pa roj no siv LEL txoj kev 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. Cov tshuaj catalytic combustion yog coated ntawm ib qho ntawm cov platinum hlau txuas hniav. 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 no yog proportional rau qhov concentration ntawm cov roj hluav taws xob, thiab qhov concentration ntawm cov roj hluav taws xob tuaj yeem xam los ntawm lub ntsuas hluav taws xob thiab microprocessor. Thermal conductivity VOL detectors uas ncaj qha ntsuas lub ntim concentration ntawm combustible gases kuj muaj nyob rau hauv kev ua lag luam, thiab muaj twb detectors uas ua ke LEL / VOL. Lub VOL combustible detector yog tshwj xeeb tshaj yog haum rau ntsuas qhov ntim (VOL) concentration ntawm combustible gases nyob rau hauv ib puag ncig tsis muaj oxygen.
Cov pa phem tuaj yeem muaj nyob rau hauv ob qho tib si cov khoom siv raw, xws li cov tshuaj lom neeg feem ntau (VOCs), thiab cov khoom los ntawm ntau theem ntawm cov txheej txheem tsim khoom, xws li ammonia, carbon monoxide, hydrogen sulfide, thiab lwm yam. Lawv yog cov teeb meem txaus ntshai tshaj plaws rau cov neeg ua haujlwm. Qhov kev puas tsuaj no tsis yog tsuas yog muaj kev puas tsuaj tam sim ntawd, xws li lub cev tsis xis nyob, mob, tuag, thiab lwm yam, tab sis kuj suav nrog kev ua phem rau tib neeg lub cev mus ntev, xws li kev tsis taus, mob qog noj ntshav, thiab lwm yam.
