The apparatus and installations included in Class 11 can be characterized as being for "environmental control" in the sense that they change the surrounding environment, for example, by heating, cooling, drying, purifying or disinfecting air or water. Consequently, Class 11 includes heating, ventilating, air-conditioning and air purification equipment, sanitary installations, water supply and water treatment installations, refrigerating and freezing equipment, as well as apparatus for cooking, heating and refrigerating food.
There can be confusion with certain electrically heated apparatus in other classes but, unlike Class 11 apparatus, electrically heated apparatus in other classes use heat in order to perform a task rather than having heating as their primary function. For instance, electric glue guns are in Cl. 7 because their purpose is to apply glue (even though heat is used to melt the glue in the gun), whereas glue-heating appliances are in Class 11 because their purpose is to melt the glue, and keep it viscous using heat, so it can then be applied to a surface using a separate tool.
It should be noted that the cooking apparatus and utensils in Class 11 have a heat source that is part of the apparatus, for example, microwave ovens, bakers' ovens, electric kettles and electric pressure cookers. Cooking utensils that do not incorporate a heat source are, generally, in Cl. 21, such as pots and pans for cooking, non-electric kettles and non-electric pressure cookers.
Pipes as parts of sanitary installations are in Class 11. There are also pipes in Cl. 6, Cl. 17 and Cl. 19. The pipes in Class 11 are those that are directly attached to, and are specialized parts of, installations such as sinks, showers and toilets. The pipes that bring water to and from these installations are building materials and are thus classified in Cl. 6 if they are made of metal and in Cl. 19 if they are rigid and not made of metal. Flexible pipes made of non-metallic materials are in Cl. 17.
Class 11 also contains lighting apparatus and certain accessories related thereto, for example, electric lamps, light bulbs and lamp shades. It should be noted that the lamps and other lighting apparatus in Class 11 are for lighting purposes. Vehicle and laboratory lights are thus in Class 11 and not, respectively, in Cl. 12 or Cl. 9. Lights that are in classes other than Class 11 are used mainly for purposes other than lighting, for example, lamps for medical purposes are in Cl. 10 and signalling lights and traffic-light apparatus are in Cl. 9. Note however that directional lights for bicycles and light bulbs for directional signals for vehicles belong to Class 11 as they are not considered to be the type of signalling light that would belong to Cl. 9.
Finally, Class 11 is the class for electrically heated clothing, such as electrically heated socks, because of the heating function of such goods. The same is true of blankets and footmuffs that are in Class 11 when they are electrically heated (and not for medical purposes) but which would otherwise belong to other classes.