Ib rab phom yog ib yam khoom siv ua kua los yog compressed cua kom tso tawm sai li lub zog. Muaj ob hom tshuaj tsuag phom: hom twj tso kua mis thiab hom pressurized. Kuj tseem muaj cov phom phom siab, phom phom carlo, thiab cov phom tsis siv neeg rov qab.Th