Structure and operationzafarMirdamad
Excluding grommets, a hookah consists of a number of components, four of which are essential for its operation.
Also known as the head of the hookah, the bowl is a container, usually made out of clay, marble, or glass that holds the coal and tobacco during the smoking session. The bowl is loaded with tobacco then covered by a screen or perforated aluminum foil. Lit coals are then placed on top, which allows the tobacco to heat to the proper temperature.
There is also a variation of the head that employs a fruit rather than the traditional clay bowl. The fruit is hollowed out and perforated in order to achieve the same shape and system a clay bowl has, then it is loaded and used in the same manner.
Bowls have evolved in recent years to incorporate new designs that keep juices in the tobacco from running down the stem. The Tangiers Phunnel Bowl and Sahara Smoke Vortex Bowl are two examples of such bowls.
A Hookah Cover windscreen is a cover that sits over the bowl area, with some form of air holes. This prevents wind from increasing the burn rate and temperature of the coal, and prevents ash and burning embers from being blown onto the surrounding environment. This may also offer some limited protection from fire as it may prevent the coal from being ejected if the hookah is bumped.
The hose (one or more) is a slender flexible tube that allows the smoke to be drawn for a distance, cooling down before inhalation. The end is typically fitted with a metal, wooden, or plastic mouthpiece of different shapes, size, color or material type. Today, the hose proper is typically made from vinyl which allows it to be easily cleaned. According to J. S. Gamble in A Manual of Indian Timbers in 1902 (p. 668), the bark of the white Himalayan birch Betula utilis ssp. jacquemontii was used to make early hookah tubes.
Many hookahs are equipped with a purge valve connected to the airspace in the water jar to purge stale smoke that has been sitting unused in the jar for too long. This one-way valve is typically a simple ball bearing sitting over a port that seals the port by gravity alone and will open if positive pressure is created by blowing into the hose. The bearing is held captive with a screw-on cover. The cover should be opened and the bearing and seat cleaned of residue and corrosion regularly to ensure proper sealing.
The body of the hookah sits on top of the water base, or sometimes referred to as vase. The downstem hangs down below the level of the water in the jar. Smoke passes through the body and out the downstem where it bubbles through the water. This cools and humidifies the smoke. Liquids such as fruit juice may be added to the water or used in substitution. Pieces of fruit, mint leaves, and crushed ice may be added.
A plate or ashtray sits just below the bowl to catch ashes falling off the coals.
Grommets in a hookah are usually placed between the bowl and the body, between the body’s gasket and the water jar, and between the body and the hose. The grommets, although not essential (the use of paper or tape has become common), will help to seal the joints between the parts, therefore decreasing the amount of air coming in and maximizing the smoke breathed in.
A piece attached to the bottom of the stem, usually made of plastic and in a grid pattern, to make a smoother smoke and a subdued noise. By breaking the naturally larger bubbles coming up the water from the pipe into smaller bubbles, it lowers the amount of suction or “pull” needed to continue bringing smoke to the chamber. This also cools the smoke down more efficiently. It is used as a luxury item used for a better smoking experience and is not a required component.
Tobacco or Mu‘assel (Arabic: معسل, which means “honeyed”), also sometimes called Shisha in places where it does not refer to the Hookah itself, is a syrupy tobacco mix with molasses and vegetable glycerol as moisturizer and specific flavors added to it. Typical flavors of mu‘assel include apple, grape, guava, lemon, mint, as well as many other fruit based mixes. Non-tobacco-based mu’assel is also available in certain areas where tobacco smoking is not allowed.
Charcoal is the source of energy to produce heat that will be transferred to the tobacco inside the bowl. Since the glycerol is used to moisturize the tobacco, then to produce smoke, the charcoal should be able to generate heat above the boiling point of glycerol that is 290 °C. Therefore, charcoal for hookah smoking must be hard, high density, easy to ignite, and burn longer with persistent heat
The jar at the bottom of the hookah is filled with water sufficient to submerge a few centimeters of the body tube, which is sealed tightly to it. Deeper water will only increase the inhalation force needed to use it. Tobacco or tobacco-free molasses are placed inside the bowl at the top of the hookah. Often the bowl is covered with perforated tin foil or a metal screen and coal placed on top. The foil or screen separates the coal and the tobacco, which reduces inhalation of coal ash from the smoke and reduces the temperature the tobacco is exposed to, in order to prevent burning the tobacco directly.
When one inhales through the hose, air is pulled through the charcoal and into the bowl holding the tobacco. The hot air, heated by the charcoal vaporizes the tobacco without burning it. The vapor is passed down through the body tube that extends into the water in the jar. It bubbles up through the water, losing heat, and fills the top part of the jar, to which the hose is attached. When a smoker inhales from the hose, smoke passes into the lungs, and the change in pressure in the jar pulls more air through the charcoal, continuing the process.
If the hookah has been lit and smoked but has not been inhaled for an extended period, the smoke inside the water jar may be regarded as “stale” and undesirable. Stale smoke may be exhausted through the purge valve, if present. This one-way valve is opened by the positive pressure created from gently blowing into the hose. It will not function on a multiple-hose hookah unless all other hoses are plugged. Sometimes one-way valves are put in the hose sockets to avoid the need to manually plug hoses.