Class K extinguishers are essential for fighting oil and grease fires that commonly occur in commercial and industrial kitchens. Class K fires are different from solid, liquid or electrical fires because they involve liquids that reach high temperatures and react differently to fire. These extinguishers are formulated with an extinguishing agent designed to react with hot oils and greases, efficiently smothering the flames.

1. Cooking oils:
   Vegetable or animal oils that are heated to high temperatures in deep fryers or frying pans and can ignite quickly if not handled properly.
2. Cooking fats:
   Fats used in food preparation can also be the cause of fires, especially if heated to very high temperatures.
3. Motor oils:
   Although not their most common use, Class K extinguishers can also be used on motor oil fires if they are found in industrial kitchen or restaurant areas where oils are similarly used.

Recommendations for customers who should purchase Class K extinguishers:

1. Restaurants and commercial kitchens:
   Restaurants, cafeterias, fast food chains, and any establishment that handles large quantities of frying oils or fats should have Class K extinguishers. Fryer or pan fires are common in these environments and pose a serious safety risk to personnel and property.
2. Industrial kitchens:
   Industrial kitchens, which are used in hospitals, hotels, universities and large food facilities, must also be equipped with Class K extinguishers to prevent fires caused by large amounts of hot oil or grease.
3. Catering and large-scale events:
   Caterers handling large capacity fryers at large-scale cooking events should have Class K extinguishers, as fryers are a common source of grease fires.
4. Corporate and school cafeterias:
   School cafeterias, corporate dining halls and institutional kitchens that use deep fryers or large amounts of cooking oil should have Class K extinguishers to be prepared for any fire incident.
5. Food processing industries:
   Food processing plants, especially those involved in high-volume frying (such as potato chip, snack and convenience food plants), require Class K extinguishers due to the high temperature of the oils and the risk of fires.
6. Fast food establishments:
   Pizzerias, taco, burger and other fast food establishments that use hot oils in the preparation of their food should have Class K extinguishers, as fires in this equipment are common due to the high temperature of the oils used in cooking.