Yog hais tias tag nrho cov ntawv xov xwm pib tshwm ntawm tus cwj mem kua (ink pressure), qhov teeb meem yog nyob rau qhov muaj qhov tsis zoo (lub siab tsis muaj qhov tsis zoo), thaum lub sijhawm no kho qhov kev ntsuas kom txog thaum tsis muaj kua.
Ib feem ntawm lub taub hau kua mem kua hauv plhaub, ib qho liab lossis xiav tshwm sim number case dripping, nws tuaj yeem hais tias qhov tsis zoo siab ntawm tag nrho lub tshuab tsis muaj teeb meem, tiam sis tus tib neeg sau taub hau ntawm qhov siab tsis zoo los yog cov ntxaij lim dej muaj teeb meem, qhov daws yog ua rau cov cua tsis tuaj yeem ua rau sab hauv. Ntsuas seb lwm cov ntawv sau taub hau los yog tsis yog, yog muaj, teeb meem hauv tov lossis lim, tsuas xav hloov lub lim, yog tias tsis yog , qhov teeb meem yog qhov nqes cua, txav valve txuas yog qhov kev daws teeb meem.
