Puas yog cov hmoov hlau ua kom zoo yog qhov kev xaiv zoo rau kev xaiv hlau?
Qhov tseem ceeb ntawm cov hlau degreeze
Hauv ntau qhov kev lag luam, los ntawm kev tsim khoom rau kev saib xyuas, cov hlau Streeting ua si lub luag haujlwm tseem ceeb. Piv txwv li, hauv kev lag luam hauv tsheb, cov khoom hlau yuav tsum yog ua ntej pleev xim rau cov xim muaj zog, uas tuaj yeem tiv thaiv corrosion thiab txhim kho cov tsos ntawm lub tsheb. Yog tias cov hlau chaw tsis yog qhov ua kom zoo rau kev ua kom zoo, cov xim yuav tev tawm yooj yim, txo lub neej tau yooj yim, txo cov nyiaj ntawm cov khoom lag luam. Hauv kev lag luam hluav taws xob, degreasing yog qhov tseem ceeb rau cov khoom siv kom paub tseeb tias yog zoo sib xws. Cov roj uas muaj roj uas muaj peev xwm ua rau cov pob qij txha tsis zoo, ua rau cov kev ua tsis tiav thiab txo cov khoom muaj kev ntseeg tau. Txawm nyob rau hauv me me- nplai kho cov dej num lossis cov pob txha av ua tau zoo nkauj thiab cov pob txha txuas tuaj yeem txhim kho cov khoom lag luam thiab cov khoom siv tau. Zuag qhia tag nrho, siv cov hlau ua tau zoo yog lub hauv paus rau kev ua kom zoo thiab ua haujlwm ntawm cov hlau {}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}} Cov khoom lag luam hauv ntau thaj teb, muaj kev cuam tshuam ntxivtab tom uaCov kauj ruam thiab thaum kawg qhov zoo ntawm cov khoom kawg.
Cov hauv paus ntawm cov hlau degree
Hlau chaw feem ntau nthuav tawm cov roj los ntawm ntau qhov chaw. Thaum lub sij hawm cov txheej txheem tsim khoom, roj nplua nyeem yog siv los txo kev sib txhuam ntawm cov hlau seem thiab cov cuab yeej. Piv txwv li, hauv cov hlau forging, cov roj ntau ntawm lubricating roj yog siv los tiv thaiv cov hlau los ntawm cov pwm. Thaum lub sij hawm cia thiab tsheb thauj mus los, cov Cheebtsam hlau yuav tau coated nrog cov roj tiv thaiv lossis roj los tiv thaiv kev xeb. Tib neeg tuav kuj tseem tuaj yeem hloov cov roj ntawm cov tawv nqaij rau hauv cov hlau. Cov roj txheem hloov tshiab tuaj yeem cuam tshuam nrog ntau cov txheej txheem tom ntej xws li vuam, thiab electroplating. Ntawm cov txheej txheem ntau yam thiab cov neeg sawv cev siv rau cov hlau xyaum, cov hmoov hlau me me tau tawm los ua qhov tseem ceeb thiab feem ntau siv. Nws muaj kev sib xyaw ua ke, raug nqi {{{{{{{}} kev siv hauv kev lag luam zoo li rau qee lub tsev {{8} Raws li cov phiaj xwm kev lag luam.
Cov kev sib xws ntawm cov hlau xyaum
Alkaline Degreeze nrog Hlau Degreeze
Tshuaj Lom Zem
Alkaline Degreat siv hlau℃cov hmoov yog ib tug dav - siv txoj kev hauv kev kho hlau nto. Cov hlau ua cov hmoov hlau feem ntau muaj cov tshuaj alkaline xws li sodium hydroxide (\\ (na_2co_3 \\ sodium carbonate (\\)), thiab sodium phosphate (\\ (na_3po), nrog rau surfactants. Qhov tseem ceeb ntawm cov tshuaj tiv thaiv tseem ceeb koom nrog yog cov tshuaj tiv thaiv saponificate thaum cuam tshuam nrog roj {}} zoo li cov roj lossis zaub ua zaub). Piv txwv li, thaum sodium hydroxide reacts nrog stearic acid (} kev tawm tsam tshwm sim: \\ (c_} Hon
Stearic acid reacts nrog sodium hydroxide los ua Sodium stearate (xab npum), uas yog soluble hauv dej, thiab dej. Qhov kev tawm tsam saponificate no tau tawg ntau lub fatty {{1} kua qaub nyob rau hauv cov roj av ntxiv, tso cai rau lawv kom yooj yim ntxuav tawm.
Surfactants hauv cov hlau xyaum tawm cov hmoov ua si lub luag haujlwm tseem ceeb hauv kev ua haujlwm. Lawv muaj ob lub hydrophilic (dej - hlub) thiab lipophilic (rog- hlub) xaus. Lipophilic xaus rau cov roj ntsha roj, thaum lub hydrophilic xaus ntsej muag dej. Qhov kev npaj no pab emulsify lub roj, ua kom nws mus rau hauv cov kua me me, ua rau nws tshem tawm yooj yim los ntawm cov hlau nto. Ib qho ntxiv, cov tshuaj zoo li sodium carbonate hauv cov hmoov tuaj yeem ua rau cov txheej txheem alkaleby thiab (Oh ^})
Daim Ntawv Thov Kev Pab Cuam
Alkaline Degreeite nrog cov hmoov hlau℃degreases yog muaj peev xwm heev thiab tuaj yeem siv rau ntau cov ntaub ntawv hlau.
Hlau: Rau cov khoom siv hlau, alkaline degreasing yog qhov ua tau zoo. Hauv kev tsim cov hlau tsheb yam li cov cav lossis cov khoom sib kis tau siv los siv cov kua roj nplua nyeem thiab cov kua dej uas tau sib sau ua kua uas tau sib sau thaum cov txheej txheem machining. Cov hmoov alkaline muaj zog ntawm cov hmoov tuaj yeem tsoo cov tshuaj organic hauv cov paug tsis huv. Txij li cov hlau yog cov tiv thaiv tsis zoo rau cov txheej txheem alkaline nyob rau hauv ib txwm muaj, kev npaj ua kom huv si xws li pleev xim, lossis cua sov {} kev kho. Piv txwv li, nyob rau hauv ib tug loj- teev tsheb ua lag luam, steel seem feem ntau tau raus hauv ib da dej ntawm Alkaline Degreat daws tau los ntawmhlauDegreasing hmoov rau qee lub sijhawm, ua raws li los ntawm kev yaug, kom ntseeg tau kom huv si rau kev ua ntxiv.
Txhuas Alloys: Txhuas Alloys tseem muaj kho nrog cov alkaline degreat. Txawm li cas los xij, kev saib xyuas tshwj xeeb yuav tsum tau xeem vim tias txhuas yog kev siv taus ntau dua nrog alkalis piv rau cov hlau. Cov hmoov nplej hlau ua rau cov hmoov txhuas alloys feem ntau muaj cov alkaline sib xyaw los tiv thaiv kev xeb ntau dhau ntawm cov npoo txhuas. Hauv kev lag luam Aerospace, qhov twg aluminium alloys tau siv dav hauv cov dav hlau, alkaline degreiting yog siv los tshem tawm cov roj uas tiv thaiv thiab paug. Cov txheej txheem daws teeb meem tsis yog tsuas yog ua kom muaj cov nplaum ntawm cov txheej txheem tiv thaiv corrosion tab sis kuj tswj cov qauv txheej txheem kev ntseeg ntawm cov kab ke aluminium. Los ntawm kev ua tib zoo tswj cov kev xav thiab lub sijhawm siv ntawm cov nyhuv degreing, qhov xav tau ua tiav yam tsis muaj kev ua kom muaj kev rhuav tshem cov khoom txhuas txhuas ntau.
Tooj liab thiab nws alloys: Tooj thiab tooj thiab tooj {- Raws alloys kuj tseem tuaj yeem tau txais txiaj ntsig los ntawm Alkaline Degreeze nrog cov hmoov hlau me me. Nyob rau hauv kev tsim cov hluav taws xob ua los ntawm tooj liab ua los ntawm cov tooj liab, xws li cov xov hlau thiab cov roj av, degreasing yog qhov tsim nyog los tshem tawm ib qho roj lossis cov khoom paug uas tuaj yeem cuam tshuam rau hluav taws xob kev ua haujlwm lossis siv cov khoom siv hluav taws xob. Lub alkaline degresing txheej txheem tuaj yeem ntxuav huv cov npoo ntawm cov ntaub ntawv tooj liab, thiab surfactants hauv cov hmoov pab kom tiv thaiv rov qab ntawm cov khoom tsis raug tshem tawm. Txawm li cas los xij, zoo ib yam li txhuas alloys yuav tsum tau ua tib zoo kho kom tsis txhob muaj kev mob corrosion lossis discoloration ntawm tus tooj liab.
Yam cuam tshuam cuam tshuam rau kev ua tau rau kev ua tau zoo rau cov hlau hluav taws xob nrog cov hmoov hlau
Concentration ntawm cov hlau xyaum ua hmoov
Qhov kev xav ntawm cov hlau xyaum tawm hauv cov kev daws teeb meem yog qhov cuam tshuam tseem ceeb uas cuam tshuam rau kev ua haujlwm zoo. Thaum lub concentration ntawm cov hmoov hlau me me yog tsawg dhau, muaj cov khoom siv tsis txaus, muaj cov roj tsis txaus thiab tshem cov roj ntawm cov hlau nto. Piv txwv li, nyob rau hauv ib qho xwm txheej uas cov hlau℃cov tshuaj surfactor thiab alkaline {{{2} {} {}} Cov roj ntsha ua kom huv si. Raws li qhov tshwm sim, cov roj yuav tsuas yog muab tshem tawm ib feem, tawm tom qab ib zaj yeeb yaj kiab nyias ntawm cov khoom seem ntawm cov hlau nto. Cov seem no tseem tuaj yeem cuam tshuam nrog cov txheej txheem tom ntej xws li pleev xim, ua rau cov xim tsis zoo ntawm cov xim thiab muaj peev xwm ua rau cov xim pleev xim rau ntxov.
Ntawm qhov tod tes, yog hais tias kev xav ntawm cov hmoov hlau me me yog qhov siab dhau, nws tuaj yeem ua rau ntau yam teeb meem. Firstly, ntau heev alkaline cov tshuaj nyob rau hauv lub siab-}}}}}}}}}} cov hlau hluav taws xob tuaj yeem ua rau muaj cov alkalis, zoo li cov alloys alloys. High {{3} Txoj kev daws teeb meem siab kuj tseem yuav ua rau muaj kev surfactants kom muaj cov ntsev {}} tawm cov teebmeem. Surfactants yog amphiphilic molecules uas yog qhov tseem ceeb rau emulsifying roj. Nyob rau hauv lub siab -}}} txoj kev xav tau tej zaum yuav muaj kev sib sau ua ke thiab cais tawm ntawm qhov chaw lossis kev sib cais nyob hauv qab ntawm kev daws teeb meem. Qhov no txo tau cov kev pom zoo ntawm cov surfactants hauv kev daws teeb meem, yog li txo qis kev muaj peev xwm. Tsis tas li ntawd, siv siab -}}}} {} {} {}} {}}
Hu rau lub sijhawm
Hu rau lub sijhawm, uas yog hais txog lub sijhawm uas cov hlau saum npoo hlau yog sib cuag nrog cov tshuaj ua paug, yog lwm qhov tseem ceeb me me hauv kev ua haujlwm degreat. Yog tias lub sijhawm tiv tauj luv heev, cov tshuaj lom neeg thiab kev sib cuam tshuam ntawm lub cev ntawm cov hmoov av degreasing thiab cov roj rau ntawm cov hlau nto tsis muaj sijhawm txaus kom tshwm sim tag nrho. Piv txwv li, hauv Saponification cov kev tawm tsam uas tshwm sim thaum cov roj av alkaline nrog cov roj, lub sijhawm sib chwv luv yuav tsis pub cov tshuaj tiv thaiv mus ua tiav. Raws li qhov tshwm sim, cov roj tsis tau hloov dua siab tshiab rau hauv soluble xab npum thiab seem ntawm cov hlau nto. Ib yam li ntawd, cov txheej txheem emulsification los ntawm surfactants tseem xav tau lub sijhawm ntawm cov roj me me rau hauv cov dej ntws me me thiab tawg ntawm lawv hauv kev daws. Nyob rau hauv high - kev siv ceev ntau heev, yog tias tus constairs cov hlau los ntawm kev ua kom zoo, ua rau cov teeb meem tsim khoom tom ntej.
Txawm li cas los xij, lub sijhawm ntev kev sib cuag ntev kuj muaj lawv cov teeb meem. Ntev nthuav dav ntawm cov hlau kom cov tshuaj kho kom haum, tshwj xeeb tshaj yog tias nws muaj cov qoob loo muaj zog xws li- corrosion ntawm cov hlau nto. Qhov no tuaj yeem ua rau kev puas tsuaj ntawm cov hlau, txo nws lub zog thiab muaj peev xwm cuam tshuam nws qhov kev ua tau zoo hauv qhov kawgkhoomCov. Ntxiv mus, ncua sijhawm sib tham tuaj yeem ua rau lub sijhawm thiab cov nqi ntau lawm. Hauv chaw muaj kev muaj, lub sijhawm yog cov khoom muaj txiaj ntsig zoo, thiab ntau lub sijhawm ua haujlwm qeeb tuaj yeem ua rau cov khoom lag luam ntau lawm, ua rau cov kev ua haujlwm tau tsawg dua. Yog li ntawd, nrhiav lub sijhawm zoo tshaj plaws, uas yuav sib txawv nyob ntawm hom hlau, thiab cov khoom siv thiab cov roj ntsha ua tau zoo thiab tus nqi {{{} Cov hlau ua tau zoo me me.
Kev Kawm Txog Cov Ntaub Ntawv: Kev Ua Tau Zoo Ua Txij Nkawm Nrog Hlau Degreule
Hauv kev lag luam tsim khoom
Ib qho zoo -}}}}}} paub qhov chaw tsim khoom lag luam uas muaj kev sib tw hauv cov txheej txheem sib tw ua ntej cov txheej txheem tha xim. Cov hlau seem, feem ntau ua los ntawm cov hlau thiab aluminium alloys, tau sau ntau yam roj hmab thaum lub tshuab machining, suav nrog cov roj thiab cov roj nplua nyeem thiab lubricants. Cov roj txheem no, yog tias tsis tshem tawm kom raug, yuav ua rau cov xim nplaum pleev xim, ua kom pleev xim pleev xim thiab corrosion ntawm qhov chaw.
Lub tuam txhab txiav txim siab txais yuav cov hlau degridreat -} Raws li cov txheej txheem alkaline degreasing. Lawv tau xaiv cov hmoov hlau ua ke nrog cov tshuaj sib npaug ntawm cov tshuaj uas tsis sib xws thiab surfactants, haum rau ob qho tib si steel thiab aluminium alloy cov ntaub ntawv. Cov txheej txheem degreast koom nrog cov hlau seem hauv kev daws teeb meem degrees ua los ntawm dissolving cov hmoov hlau tawm hauv dej. Kev suav cov hmoov ntawm cov hmoov av degreasing hauv kev daws tau ua tib zoo kho kom zoo rau 5% (Mass {}} kev sim siab thiab theoretical suav.
Lub sijhawm sib cuag tau teeb tsa 10 feeb. Nyob rau lub sijhawm no, cov tshuaj Alkaline hauv cov hmoov hlau ua kom zoo nrog cov roj ntsha ntawm cov hlau saum npoo av ntawm saponification cov kev tiv thaiv, tawg lawv rau hauv Soluble xab npum. Lub surfactants emulsified qhov tsis- roj roj, ua kom yooj yim rau ntxuav kom deb. Tom qab degreasing, cov seem tau muab yaug nrog dej kom tshem tawm cov tshuaj ntxiv thiab yaj yeej paug.
Cov txiaj ntsig tau zoo tshaj plaws. Cov xim pleev xim rau ntawm cov hlau degrased hlau uas tau txhim kho. Nyob rau hauv ib qho xim nplaum pleev qhov kev kuaj, qhov twg tus ntoo khaub lig {2} Tus qauv daug lawm, sib ntsib rau cov xim sib txawv ntawm qhov tsawg dua 10% xim tshem tawm rau cov adhesion zoo. Qhov kev txhim kho no nyob rau hauv cov xim pleev xim kuj ua kom cov corrosion tsis kam ntawm feem. Nyob rau hauv ntsev - tsuag tsuag tsuag, qhov chaw ua kom pom tseeb rau cov paib yav dhau los, uas yog qhov ua tau zoo tshaj plaws rau kev saws me ntsis {}} Raws li cov txheej txheem.
Los ntawm kev pom kev lag luam, kev siv cov hmoov hlau degrge degreuching kuj tau coj tus nqi - kev txuag. Tus nqi ntawm cov hmoov hlau me me yog qhov tsis tshua muaj qhov piv rau qee cov organic kuab {} los ntawm cov neeg sawv cev. Ib qho ntxiv, lub tuam txhab txo tus naj npawb ntawm kev ua haujlwm ua haujlwm vim muaj kev txhim kho xim zoo, txuag ob lub sijhawm thiab nyiaj txiag. Cov txheej txheem ntau dua tag nrho tau nce los ntawm 15% raws li cov txheej txheem degreast tau muaj txiaj ntsig ntau dua thiab tsawg} kev siv dua li cov txheej txheem yav dhau los.
Hauv kev saib xyuas thiab kho
Ib lub tshuab khoom siv tu tau cov khoom lag luam tu nrog kev kho thiab txij nkawm ntawm loj - teev muaj machine. Cov cav no muaj cov hlau sib xyaw uas tau ntau dua cov roj av nrog roj teeb sib xyaw, roj, thiab hmoov av tom qab ua haujlwm ntev. Tus txheej txheem tswj xyuas yuav tsum tau ua kom tiav degreeast ntawm cov hlau seem kom ntseeg tau tias cov khoom siv du tshiab thiab kev ua haujlwm du ntawm cov tshuab.
Lub Hoobkas pib siv cov hmoov hlau ua rau nws cov haujlwm ua haujlwm degreece. Cov khoom siv hlau me me tau xaiv rau nws qhov siab- Kev ua tau zoo ntawm cov tshuab hlau, xws li cam khwb cia hlau, cov hlau cam khwb cia siv rau hauv cov hlau, thiab hlau quav.
Rau cov txheej txheem degreating, lub Hoobkas ua ntej npaj kev daws los ntawm kev sib xyaw cov hlau ua hmoov nrog dej kub ntawm qhov kub ntawm 60 degree. Qhov kev pom zoo ntawm cov hlau xyaum tawm hauv qhov kev daws teeb meem tau tswj hwm ntawm 8% (Mass {}}}}}}} kev ntim piv). Cov hlau seem tau ces tsau rau hauv cov degreasinglus tebrau 15 feeb. Cov dej kub thiab lub siab siab-}}} regrubring hmoov daws tau pab kom ua kom nrawm txheej txheem degreast. Cov txheej txheem Alkaline hauv cov hmoov tawm tsam cov roj, thaum lub surfactaned txhim kho emulsification thiab dispersion ntawm cov roj ntsha roj hauv txoj kev daws.
Tom qab soaking, cov seem tau txhuam maj mam muab nrog cov mos mos -} dirmin txhuam kom tshem tau cov khoom tsis huv. Tom qab ntawd, lawv tau yaug kom huv si nrog dej huv thiab qhuav. Cov nyhuv tiag tiag ntawm kev siv cov hmoov hlau degreasing yog qhov zoo. Cov khoom ntawm cov hlau degregose tawm pom theem siab ntawm kev nyiam huv. Qhov saum npoo av ntawm cov ntu degreash, ntsuas siv cov ntsuas ntawm 5 micrometer ua ntej ntawm qhov nruab nrab ntawm 5 tus micrometer tom qab degreasing thiab reficing ib tug smoother thiab huv si. Qhov saum npoo huv no yog qhov tseem ceeb heev rau kev ua haujlwm zoo ntawm cov tshuab raws li nws txo kev sib txhuam ntawm txav chaw.
Hais txog kev ua tau zoo ntawm kev kho tshuab, kev siv ntawm cov hlau degreasing hmoov {}} kev txo qis hauv cov tshuab ua tsis taus. Hauv peb {{- lub hlis tom qab kev saws me me rau kev saib xyuas tsis huv rau ntawm 60% piv rau tib lub sijhawm hauv xyoo dhau los. Qhov no tsis tsuas yog khaws cov Hoobkas los ntawm kev kho tus nqi tsim kho thiab tseem txhim kho qhov kev ntseeg siab tag nrho thiab siab dua ntawm cov kev pab cuam tag nrho, muab kev pabcuam zoo dua rau lawv cov neeg siv khoom.
Kev sib cav sib ceg? Regsessing hlau degreasing hmoov lub luag haujlwm ntawm kev ua kom zoo tshaj plaws hlau me me
Cov ntsiab lus ntawm cov ntsiab lus tseem ceeb
Hauv cov ntsiab lus, cov hlau xyaum yog qhov txheej txheem tseem ceeb hauv kev lag luam ntau yam hauv kev lag luam, nrog alkaline degreasing siv hlau degreasing hmoov ua ib txoj kev saws. Cov kev siv tshuaj lom neeg muaj feem cuam tshuam nrog, xws li saponification thiab emulsification los ntawm cov khoom siv hauv kev tshem tawm cov roj av ntawm cov hlau.
Kev ua haujlwm ntawm cov hlau xyaum tawm nrog cov hmoov hlau℃yog qhov cuam tshuam zoo heev los ntawm cov hmoov ntawm cov hmoov hauv kev daws thiab lub sijhawm sib tiv tauj. Kev tswj kom muaj kev txiav txim siab tsim nyog kom muaj cov tshuaj uas tsis muaj kev ua kom muaj cov tshuaj uas tsis muaj teeb meem xws li cov teeb meem hlau los yog ntsev surfactant- tawm. Kev txiav txim siab lub sijhawm hu tau yog qhov tseem ceeb kom tso cai rau kev ua kom tiav tshuaj lom neeg lub cev thaum tiv thaiv kev txhim kho thiab lub sijhawm tsis tsim nyog thiab noj.
Kev tshawb nrhiav kev lag luam los ntawm kev lag luam tsim thiab kho thiab kho cov teb tau pom tau ua kom zoo ntawm cov hmoov hlau. Hauv kev lag luam lag luam, nws tau txhim kho qhov zoo ntawm cov txheej txheem txuas ntxiv zoo li kev pleev xim, ua kom zoo dua- cov khoom lag luam zoo nrog kev txhim kho corrosion. Hauv kev saib xyuas thiab kho, nws tau txhim kho kev huv huv ntawm cov hlau seem, txo cov neeg kho tshuab tsis ua haujlwm thiab txhim kho kev ntseeg tau ntawm cov tshuab. HlauncabHmoov, nrog nws cov tshuaj sib xyaw ua ke thiab cov khoom siv, tau ua pov thawj los ua qhov cuab yeej tsis tseem ceeb hauv cov ntawv thov ua tiav.
Outlook rau kev siv cov hlau
Saib tom ntej, cov hlau xyaum kev lag luam yuav tsum tau txuas ntxiv mus ntxiv. Nrog rau Kev Tiv Thaiv Ib puag ncig ntawm kev tiv thaiv ib puag ncig, yuav muaj kev cog lus rau cov hmoov ua kom zoo nkauj ib puag ncig. Cov hmoov no yuav muab ntau dua biodegradable surfactants thiab tsawg-} {{{{3} {{{3} {{kev kho khib nyiab.
Cov txheej txheem thev naus laus zis kuj yuav muaj peev xwm coj los ua cov txheej txheem zoo dua. Piv txwv li, txoj kev txhim kho ntawm cov khoom siv ntse ntawm cov khoom muaj peev xwm ntawm cov hlau ua kom zoo thiab lub sijhawm sib cuag raws li hom hlau thiab qib ntawm cov roj paug tsis huv. Qhov no yuav ua kom ua tau zoo dua rau cov txheej txheem degreighze, txuag cov khoom siv thiab txhim kho ntau lawm.
Txhawb cov kws tshawb nrhiav thiab kev lag luam raug nquahu kom txhawb nqa cov qauv tshiab txuas ntxiv thiab thev naus laus zis hauv cov hlau xyaum. Qhov no tuaj yeem koom nrog kev txhim kho ntawm cov hmoov hlau xyaum tawm nrog cov hmoov ua haujlwm, xws li cov uas tuaj yeem ua haujlwm ntawm qhov chaw kub qis dua, txo qis zog. Los ntawm kev ua li ntawd, cov hlau xyaum kev lag luam tuaj yeem ua tau zoo dua li kev xav tau ntawm ntau yam kev lag luam, ua rau qhov siab- zookev tsimntawm cov hlau -} Raws cov khoom yav tom ntej.