LEL (Lower Explosive Limit) yog hais txog qhov Lower Explosive Limit concentration ntawm cov pa. A 20% LEL qhia tau hais tias qhov concentration ntawm cov pa hluav taws xob hauv ib puag ncig tau mus txog 20% ntawm nws qhov kev txwv qis dua. Lub sijhawm no, lub tswb yuav ceeb toom. Piv txwv li, LEL ntawm methane yog 5% los ntawm ntim concentration, thiab 20% LEL yog 1% VOL concentration.
CovLEL gas ntesyog ib qho cuab yeej tshwj xeeb rau kev kuaj xyuas qhov concentration ntawm cov pa roj carbon monoxide thiab siv dav hauv kev lag luam xws li kev tsim khoom, roj av, tshuaj engineering, mining, thiab kev tiv thaiv hluav taws. Lub luag haujlwm tseem ceeb ntawm LEL gas detector yog los saib xyuas qhov concentration ntawm cov pa hluav taws xob hauv ib puag ncig hauv lub sijhawm. Thaum qhov ntsuas pom tau nce mus txog lossis tshaj qhov pib, uas yog, LEL tus nqi, nws yuav tshaj tawm lub tswb ceeb toom rau cov neeg ua haujlwm kom ntsuas kev nyab xeeb.
1.Lub ntsiab lus ntawm LEL
(1) Kev txwv tsis pub tawg: LEL tus nqi yog hais txog qhov qis tshaj plaws uas cov pa hluav taws xob tuaj yeem tawg thaum sib xyaw nrog huab cua. Txhua cov roj hluav taws xob muaj nws qhov tshwj xeeb tawg txwv, uas txawv nyob ntawm seb hom roj thiab ib puag ncig xws li kub thiab siab.
(2) Cov Qauv Kev Nyab Xeeb: Tus nqi LEL yog lub hauv paus tseem ceeb rau kev tsim cov qauv kev nyab xeeb. Hauv kev tsim khoom lag luam, kev nkag siab thiab kev paub txog LEL tus nqi ntawm cov hluav taws xob hluav taws xob yog pab tau rau kev tsim cov txheej txheem kev nyab xeeb tsim nyog thiab tiv thaiv qhov tshwm sim ntawm hluav taws kub thiab tawg.
(3).Nrhiav qhov pib: Qhov ntsuas pib ntawm LEL gas detectors feem ntau yog teem rau ntawm 20% mus rau 50% ntawm tus nqi LEL ntawm cov pa taws. Thaum qhov ntsuas tau pom cov pa roj mus txog qhov pib no, lub tshuab ntes yuav suab lub tswb, ua rau cov neeg ua haujlwm ntsuas kev kub ntxhov, xws li txiav tawm cov pa roj thiab qhov cua thiab sib pauv huab cua.
2.Lub hauv paus ntsiab lus ua haujlwm ntawm LEL gas detector
(1).Sensor: Cov khoom tseem ceeb ntawm LEL ntes yog lub sensor. Cov hom sensors muaj xws li catalytic combustion type, infrared type, electrochemical type, thiab lwm yam. Cov sensors no tuaj yeem teb rau cov roj tshwj xeeb thiab hloov cov roj ntau rau hauv cov teeb liab hluav taws xob.
(2).Signal processing: Cov teeb liab hluav taws xob tsim los ntawm lub sensor yog ua tiav los ntawm kev nthuav dav, lim, analog- rau - digital hloov dua siab tshiab, thiab lwm yam, thiab tom qab ntawd xa mus rau microprocessor rau kev tshuaj xyuas thiab suav.
(3).Display thiab Tswb: Lub microprocessor piv thiab txiav txim cov teeb liab raws li preset LEL tus nqi. Thaum pom cov roj concentration nce mus txog lossis siab dua tus nqi LEL, lub tshuab ntes yuav tshaj tawm lub tswb rau cov neeg ua haujlwm los ntawm lub suab thiab lub teeb ceeb toom, tso saib cov lus ceeb toom thiab lwm yam.
3.Qhov tseem ceeb ntawm LEL gas detectors
(1) Kev tiv thaiv kev sib tsoo: LEL roj ntes tuaj yeem ntes cov pa hluav taws xob tam sim ntawd, tiv thaiv hluav taws thiab tawg los ntawm cov pa roj.
(2) Kev tiv thaiv cov neeg ua haujlwm kev nyab xeeb: Yog tias qhov ntsuas ntawm cov pa hluav taws xob ntau tshaj li tus qauv, LEL roj ntes tuaj yeem muab lub tswb ceeb toom rau cov neeg ua haujlwm kom khiav tawm ntawm thaj chaw txaus ntshai thiab tiv thaiv lawv lub neej.
(3) Txhim khu kev ua haujlwm zoo: Los ntawm kev saib xyuas cov roj hluav taws xob hauv lub sijhawm tiag tiag, LEL cov khoom siv hluav taws xob pab txhawm rau txheeb xyuas thiab tswj cov xwm txheej txawv txav thaum lub sijhawm tsim khoom, txo cov khoom tsis ua haujlwm thiab kev cuam tshuam ntau lawm, thiab txhim kho kev tsim khoom.
LEL gas detector yog ib qho tseem ceeb ntawm kev tiv thaiv kev nyab xeeb. Los ntawm kev saib xyuas cov ntsiab lus ntawm cov nplaim hluav taws xob hauv lub sijhawm tiag tiag, nws tuaj yeem tiv thaiv hluav taws kub thiab tawg tau zoo thiab tiv thaiv kev nyab xeeb ntawm cov neeg ua haujlwm thiab cov khoom siv.