Aug 2020

Industrial Fryers

Industrial fryers are used in the food industry to produce all kinds of pre-cooked foods and snacks including french fries, chicken wings and tortilla chips just to name a few. Large fryers can contain up to 5,000 gallons of cooking oil and might operate at temperatures of up to 670°F. The oil might be heated by steam or by a heat transfer fluid system; or it could be circulated to an external direct fired heater. Exhaust systems for the fryer hood usually have wet scrubbers to capture oil in the exhaust stream, but sometimes they might have fume incinerators.

In this article, we are focusing on large continuous type fryers where “raw” product is conveyed in one end of the fryer and cooked product is conveyed out the other end. However, many of the principals discussed can be applied to smaller batch type fryers as well.

Fires involving fryers of all kinds can be intense and difficult to control. The oil reservoir itself is only one small aspect of the overall fire exposure. Crumbs and oil residue collect inside exhaust ducts, on adjacent equipment, and may accumulate on nearby walls, floors, and ceilings. If a fire is not quickly controlled, it can spread quickly throughout the area.

For protection of the fryer itself, deluge water spray or water mist is usually preferred. The systems should be automatically actuated by a suitable detection system, and there should also be a means to manually activate the system. When the system activates, an interlock should shut down the oil heating and circulation systems, fryer exhaust and the conveyor systems.

Older fryers sometimes still have CO2 systems installed for protection. However, since the discharge duration of CO2 systems is relatively short (typically 30 seconds), metal surfaces around the oil do not have time to cool and experience has shown that fires often reflash. Water spray and water mist systems will operate for an extended period of time after the fire is initially extinguished until all surfaces have adequately cooled.

Wet chemical and dry chemical extinguishing systems are often used on commercial kitchen type installations in restaurants and hotels. However, with large industrial fryers, clean up after discharging such a system could result in extended down time.

As mentioned previously, protecting the fryer itself is only half the concern for industrial fryer operations. The following areas also require protection:

  • Ceiling sprinklers should be installed throughout the room where the fryer is located. This would typically be designed for an Extra Hazard Group 1 occupancy per NFPA 13.
  • Protection is needed below mezzanines and walkways, below the fryer, and for other areas obstructed from the protection provided by the ceiling sprinkler system. Follow the guidelines for obstructions found in NFPA 13.
  • Exhaust ducts, crumb filters and drain boards require protection. These can be protected by extending the fryer protection system (deluge water spray or water mist), or they can be protected by closed head sprinklers. The best course of action for these situations is generally based on an engineering evaluation of the hazards involved.

Other items that should be considered include:

  • Alarms and interlocks – High oil temperature and low oil level are just a couple of the alarms and interlocks that should be provided for the fryer.
  • Transition of product from the fryer into adjacent blast freezers – Oil often condenses out of the air and accumulates around these transition points. There can be concealed spaces that are not adequately protected by overhead sprinkler systems. The freezer enclosures may be constructed out of metal panels with combustible insulation (see other Risk Logic articles discussing insulated metal panels).
  • Housekeeping – Oil residue often accumulates on walls, floors, and ceilings in the fryer area; and also on adjacent equipment and structures. Cleaning schedules should be developed for all surfaces to help limit accumulations.
  • Roofs – Check roofs around exhaust ducts frequently for oil buildup. If accumulations are noticed, they should be cleaned up promptly and equipment should be investigated for possible malfunction. Fires can spread through exhaust ducts and onto the roof. Oil accumulations on the roof can ignite, making fire control much more complicated.

This is a high-level overview of protection generally recommended for industrial food fryers. Contact Risk Logic for additional guidance on property loss prevention guidance on industrial fryers and similar food processing operations.