Prior to 1994, most commercial cooking involved animal fat. These deep fryers were poorly insulated which made cooking temperatures inconsistent. The extinguishing unit that protected those kitchens was a dry-chemical system which would smother the fire.
Today, vegetable oils are used in commercial cooking. These vegetable oils heat to cooking temperatures very quickly. Today’s deep fryers also have excellent heat retention and are well insulated. Because of these advances, dry chemicals are no longer effective in extinguishing a fire.
UL300 systems use Wet Chemicals that serve two purposes:
1. Similar to Dry Chemicals, they smother the fire
2. Unlike Dry Chemicals, they cool the liquids so they do not re-ignite
When a fire starts in a protected area, heat sensitive links activate that kitchen hood system. The system stops the cooking appliance’s gas or electric supply. An extinguishing agent releases through nozzles and onto the appliances, plenum and duct.
NOTE: You should also have a class K fire extinguisher close, just in case the system fails to act or a re-flash occurs.
Kitchen hood systems have an automatic detector response that acts fast to suppress flames. Kitchen hood systems eliminate the need for a constant supply of the suppressing agent and manual shut off of the appliance’s gas and electric, while blocking any danger of a violent reaction that may spread flame or spill cooking oil. The wet chemicals suppress a fire by a process called saponification. Saponification is a chemical reaction that occurs when a vegetable oil or animal fat is mixed with a strong alkali. Saponification value is a measure of the amount of potassium hydroxide needed to neutralize one gram of fat or oil.