How Does a Hookah Work?
The hookah is setup in the configuration shown to the right. The vase is filled with water to submerge the down stem. The bowl is then covered with a perforated foil sheet or metal screen. The hot coals are placed on top of the foil sheet or metal screen, which causes the tobacco in the bowl to heat up and smoke. Sucking through the hose draws more heat on the tobacco and helps accelerate the heat transfer.
By sucking on the hose, the smoke is drawn down through the down stem and underwater. The smoke then rises up above the water in the vase and into the hose port opening. The hose port opening connects directly to the hose port and does not connect to any part of the main stem or down stem. The smoke continues its path through the hose port and hose until it reaches the smoker's mouth.
The release valve is not a necessary component for the hookah to function. However, it is useful. It is used for clearing out stagnate smoke. By blowing into the hose, smoke is pushed back into the vase and through the release valve port opening up to the release valve. The air pushing up through the release valve causes a metal ball bearing to rise up, which allows the smoke to be released. The ball bearing is in the check valve to keep the hookah air tight when smoke is being inhaled.