Deep fat fryers are used for cooking many fast foods and today commercial fryers can come with an array of different features. They obviously have a basket to raise the food out of the oil when the cooking is completed, but they can have all sorts of other features too. Some have an automatic device to lower the basket into the oil when it is ready and lift it out again when cooking has ended.
They may also have an audible alarm, and mechanical or electronic temperature controls. Some have ventilation systems to reduce the smell of frying, oil filters to extend the useable life of the oil, and systems to prevent food crumbs being overcooked.
Many commercial fryers are highly energy efficient, especially those using convection heating or infra-red heating, but they can be expensive to purchase in the first place. The more common fryers are either electric or gas operated. Counter top models are often electric and are popular because they are portable. Because the heating elements are immersed in oil, they tend to lose less heat than a gas model, and they recover faster between frying cycles, but gas fryers heat up faster and they also go to higher temperatures. A typical electric fryer only goes up to 190°F. Gas fryers can be powered by either LPG or natural gas and both are cheaper to run than electric.
The materials used for commercial fryers are usually stainless steel or mild steel. Stainless steel is preferable because it is not likely to corrode or stain as mild steel can, and it doesn't expand under the heat, which can also happen with mild steel and cause the welds to become damaged.
Many of the latest commercial fryers have electronic temperature controls which continuously sense the temperature of the oil and adjust it accordingly in order to ensure perfect cooking, and also to save on fuel. A safety thermostat will also shut off the heat instantly if the oil should reach a dangerous temperature, so preventing oil fires. Most fryers have a re-set button to re-set the safety device when the fryer has cooled down, but if one is not fitted, the fryer may need repair or even scrapping if the safety device has activated.
Commercial fryers are manufactured with different types of pot. Some of them have a zone at the bottom of the pot which is cooler, and when larger food particles sink into them it keeps them from burning and affecting the oil. A fryer which is of the tube style has a large cool area because the tubes are above the bottom of the vat which leaves more space for cooler oil and crumbs. This is a useful feature if you are cooking foods that are heavily breaded, but tube style pots are more difficult to clean than an open pot. Tube style pots are also usually a little less expensive than an open fry pot. However, open fry pots - while being easier to clean and a tad more expensive – have a smaller cool zone so crumbs that fall to the bottom could scorch and taint the oil. They work very well for lightly breaded food, though.
Flat bottomed fryers have no cool zone and can also be more difficult to clean, but you can insert a batter trapper which keeps the batter from burning on the bottom which is where the heat is.
There are many manufacturers of commercial deep fryers, one of which is Parry, which makes electric, gas, and LPG fryers, and has a total of twenty different models. Parry fryers can be stand alone or integrated into a run if desired. The fryers are all made from stainless steel and the electric models can be floor standing, of which there are four models, or counter top models which total ten. There are single and double Parry fryers all of which have a traditional wire basket. There are also single and double stand-alone gas fryers in natural gas or LPG and a choice of two counter top models – one using natural gas and one using LPG – both of which are double gas fryers.