2. Nruab nrog cov khoom txwv thiab qhov siab txwv cov khoom siv kom tsis txhob muaj kev puas tsuaj rau cov khoom siv xa hluav taws xob valve
Tsis hais txog ntawm cov hluav taws xob cov twj tso kua mis, cov khoom siv sib kis valve feem ntau puas lawm vim qhov ntau dhau ntawm lub qhov ncauj ntawm cov khoom siv thaum lub sijhawm ua haujlwm ntau lawm. Txhawm rau kom tsis txhob muaj qhov nrawm thiab loj ntxiv ntawm qhov ntsuas lub zog thaum lub sijhawm ua haujlwm ntawm cov cuab yeej siv khoom, ib qho kev txwv yuav tsum tau teem rau ntawm lub tshuab xa hluav taws xob valve. Ntaus thiab txwv lub zog thiab lub zog txwv lub sijhawm.
