A barbecue grill is a device for cooking food by applying heat directly from below. There are several varieties of such grills, with most falling into one of two categories: gas-fueled and charcoal. There is great debate over the merits of charcoal or gas for use as the cooking method between barbecue grillers.

Parts

Many gas grill components can be replaced with new parts, adding to the useful life of the grill. Though charcoal grills can sometimes require new cooking grids and charcoal grates, gas grills are much more complex, and require additional components such as burners, valves, and heat shields.

A. Burners

A gas grill burner is the central source of heat for cooking food. Gas grill burners are typically constructed of:

• stainless steel
• aluminized steel
• cast iron (occasionally porcelain-coated)

Burners are hollow with gas inlet holes and outlet ‘ports’. For each inlet is a separate control on the control panel of the grill. The most common type of gas grill burners are called ‘H’ burners and resemble the capital letter ‘H’ turned on its side. Another popular shape is oval. There are also ‘Figure 8’, ‘Bowtie’ and ‘Bar’ burners. Other grills have a separate burner for each control. These burners can be referred to as ‘Pipe’, ‘Tube’, or ‘Rail’ burners. They are mostly straight since they are only required to heat one portion of the grill.

Gas is mixed with air in venturi tubes or simply ‘venturis’. Venturis can be permanently attached to the burner or removable. At the other end of the venturi is the gas valve, which is connected to the control knob on the front of the grill.

A metal screen covers the fresh air intake of each venturi to keep spiders from clogging the tube with their nests.

B. Cooking grid

Cooking grids, also known as cooking grates, are the surface on which the food is cooked in a grill. They are typically made of:

• Stainless steel (Usually the most expensive and longest-lasting option, may carry a lifetime warranty)
• Porcelain-coated cast iron (The next best option after stainless, usually thick and good for searing meat)
• Porcelain-coated steel (Will typically last as long as porcelain-coated cast iron, but not as good for searing)
• Cast iron (More commonly used for charcoal grills, cast iron must be constantly covered with oil to protect it from rusting)
• Chrome-plated steel (Usually the least expensive and shortest-lasting material)

Cooking grids used over gas or charcoal barbecues will allow fat and oil to drop between the grill bars, which will cause flare up where flames can burn and blacken food long before it is safely cooked.

To reduce the occurrence of flare up, some barbecues may be fitted with plates, baffles or other means to intercept the dripping flammable fluids.

Most high end barbecue grills use stainless steel grates, but there is a health benefit to using bare cast iron grids. When cast iron is used to cook food containing high level of acidity, such as lentils, tomatoes, lemonade sauces, or marinades with strong vinegar content, there is increased iron dietary intake.^[11]

According to the Centers for Disease Control and Prevention, iron and iron deficiency is a particularly important issue for pregnant women and young children.^[12]

The longer and hotter the grilling temperature, the more iron is infused into the food. This process can only take place with plain cast iron grids – without any form of porcelain or other types of coating. The downside to bare cast iron is that it sticks to the food and can be hard to clean.

C. Rock grate

Rock grates are placed directly above the burner and are designed to hold lava rock or ceramic briquettes. These materials serve a dual purpose – they protect the burner from drippings which can accelerate the deterioration of the burner, and they disperse the heat from the burner more evenly throughout the grill.

D. Heat shield

Heat shields are also known as burner shields, heat plates, heat tents, radiation shields, or heat angles. They serve the same purpose as a rock grate and rock, protecting the burner from corrosive meat drippings and dispersing heat. They are more common in newer grills. Heat shields are lighter, easier to replace and harbor less bacteria than rocks.

Like lava rock or ceramic briquettes, heat shields also vaporize the meat drippings and ‘infuse’ the meat with more flavor.

E. Valves

Valves can wear out or become rusted and too difficult to operate, thus requiring replacement. A valve is unlike a burner in that a replacement usually must match exactly to the original in order to fit properly. Therefore, many grills are disposed of when valves fail, due to a lack of available replacements.

If a valve seems to be moving properly, but no gas is getting to the burner, the most common cause for this is debris in the venturi. This impediment can be cleared by using a long flexible object.

F. Cover

A barbecue cover is a textile product specially designed to fit over a grill so as to protect it from outdoor elements such as sun, wind, rain and snow, and outdoor contaminants such as dust, pollution, and bird droppings.

Barbecue covers are commonly made with a vinyl outer shell and a heat resistant inner lining, as well as adjustable straps to secure the cover in windy conditions. The cover may have a polyester surface, often with polyurethane coating on the outer surface, with polyvinyl chloride liner.

Source: http://en.wikipedia.org/wiki/Barbecue_grill