How Shisha works
This basic overview will help you understand how hookah works. First, take a look at the hookah setup in the configuration shown on the picture above. The vase, or the base, is filled with water to submerge the down stem. The bowl is then covered with a perforated foil sheet or metal screen, and then 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 goes underwater. The smoke travel through the water then rises up into the air in the vase, becoming cooler and more dilute, before it reaches 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 airtight when smoke is being inhaled.