1. Qhov hnyav ntawm tuj hnab yog 0. 5-3 t.
2. Raws li cov ntsiab lus ntawm cov khoom, lawv muab faib ua ob pawg: cov hnab ntim thiab pob ntawv me me, uas haum rau ib zaug siv thiab hloov siv.
3. Raws li cov duab, tuj lub hnab tau muab faib ua peb hom: puag ncig, square thiab U-puab.
4. Txoj kev teeb tsa kev dai saum toj dai hom, sab dai rau ntawm dai thiab hauv qab dai yam, feem ntau nrog inlet thiab qhov hluav taws xob.
Nyoos cov khoom muaj ntau cov kev siv, tshwj xeeb tshaj yog rau cov khoom siv roj av, pub roj av, thiab cov khoom lag luam tsis txaus xws li calcium carbide. Chaw thau khoom, thauj khoom, tsheb thauj mus los thiab kaw cia yog yooj yim heev. Nyoos cov khoom lag luam yog nyob rau hauv cov kev txhim kho ntawm kev loj hlob, tshwj xeeb yog ib-tuj thiab pallet-puab tuav ib lub thawv ntim ib lub hnab, lossis plaub ntim) yog nrov dua.