science

Kitchen hood

Kitchen hood is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Kitchen hood rather than just read about it. In short: A kitchen hood, exhaust hood, hood fan, extractor hood, or range hood is a device containing a mechanical fan that hangs above the stove or cooktop in the kitchen. It removes airborne grease, combustion products, fumes, smoke, heat, and steam from the air by evacuation of the air and filtration.

Key takeaways

Kitchen hood belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Kitchen hood to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Kitchen hood from memory before moving on to harder problems.

Reference excerpt

A kitchen hood, exhaust hood, hood fan, extractor hood, or range hood is a device containing a mechanical fan that hangs above the stove or cooktop in the kitchen. It removes airborne grease, combustion products, fumes, smoke, heat, and steam from the air by evacuation of the air and filtration. In commercial kitchens exhaust hoods are often used in combination with fire suppression devices so that fumes from a grease fire are properly vented and the fire is put out quickly. Commercial vent hoods may also be combined with a fresh air fan that draws in exterior air, circulating it with the cooking fumes, which is then drawn out by the hood. In most exhaust hoods, a filtration system removes grease (the grease trap) and other particles. Although many vent hoods exhaust air to the outside, some recirculate the air to the kitchen. In a recirculating system, filters may be used to remove odors in addition to the grease.

Names The device is known as an extractor hood in the United Kingdom, as a range hood in the United States, and as a rangehood in Australia. It is also called a stove hood, hood fan, cooker hood, vent hood, or ventilation hood. Other names include cooking canopy, extractor fan, fume extractor, and electric chimney.

Description An extractor hood consists of three main components: a skirt or capture panel to contain the rising gases (also known as the "effluent plume"), a grease filter, and a fan for ventilation. Extractor hoods may be ducted (or vented) or ductless (or recirculating). Ducted hoods blow the gases to the outdoors; ductless hoods filter the air, often using activated charcoal, to remove odor and smoke particles from the air and then release the cleaned air back into the kitchen. Larger hood overhangs are recommended to help contain cooking fires within the area protected by the fire suppression system. Exhaust hoods almost always include built-in lighting to illuminate the cooking surface. Extractor hood controls are typically electronic, though some low-end models use electromechanical controls. Extractor hoods with electronic controls can offer remote control, motorized height adjustment, thermal sensor, overheat protection, boost mode, delayed shut-off, filter cleaning reminder, active noise cancellation, temperature display, user presets (memory), and so on. Extractor hoods may be made from a variety of materials, including stainless steel, copper, bronze, nickel silver, zinc, tempered glass, wood, aluminum, brass, heat-resistant plastics, and more. NFPA 96 Standard for Ventilation Control and Fire Protection of Commercial Cooking says that mesh filters shall not be used. It requires that "Listed" grease filters shall be tested in accordance with UL 1046, Standard for Grease Filters for Exhaust Ducts. Hood air flow is measured in liters per second (L/s), cubic meters per second (m3/s), or cubic feet per minute (cfm). Energy efficiency is evaluated based on the power consumption relative to airflow output, encouraging the use of energy-efficient DC (direct current) motors and electronically commutated motors (ECMs) in modern range hoods.

Types

Kitchen hoods are broadly classified into ducted hoods and ductless hoods. This classification of kitchen hoods is based purely on how the hoods process the incoming air. Range hoods are kitchen ventilation systems designed to remove smoke, steam, heat, grease, and cooking fumes through ducted or recirculating exhaust systems. Common types include wall-mounted, ceiling-mounted, roof-mounted, and downdraft range hoods, each differing in installation method, ventilation design, and suitability for particular kitchen layouts. A ducted system removes all forms of airborne contamination, whereas a ductless one recirculates heat and moisture. In addition, a ducted application eliminates the need for regular replacement of the filters and avoids the airflow restriction (and the resultant loss of power) caused by them. However, the ducted application can be impractical, due to lack of space or ability to install a duct system, make-up air requirements, or the additional cost of heating or cooling the make-up air.

Ducted kitchen hoods Ducted kitchen hoods are the most common and a primary type of kitchen hood. As the name suggests, a ducted kitchen hood has a duct that is used to process and expel any smoke that is generated on top of the kitchen hob. Large sized duct hoods are widely used not just in homes but also in commercial restaurants and communal kitchens too. Wall-mounted systems are among the most common and affordable options and are typically suited to kitchens where the cooktop is positioned against a wall, while ceiling-mounted and roof-mounted systems are more commonly associated with modern or high-end kitchen designs. Downdraft systems vent air downward from the cooktop area rather than upward. Factors influencing suitability include ventilation access, kitchen structure, cost, and cooking requirements. Although range hoods may vent through an external wall, roof venting is generally considered more effective, particularly in modern homes. Roof venting typically allows for shorter and straighter ducting, improving airflow efficiency, reducing operating noise and grease buildup, and providing improved performance for high-powered range hoods. It also avoids visible exterior wall vents and allows hot, moisture-laden air to rise and exit more efficiently from the building.

Ductless kitchen hoods Ductless kitchen hoods do not have a duct that is used to process the air. Instead, it makes use of strong air filtration and then pumps out the air back into the room. These types of range hoods are usually used in houses. Many homes use recirculating range hoods, which filter air and return it to the kitchen rather than venting it outside. While effective at reducing some odours and airborne particles, they do not fully remove steam, moisture, grease, smoke, or lingering cooking odours, which over time may contribute to mould growth and damage to paint, cabinetry, and ceilings.

Filters

Filters remove most odors and particulates, including grease, from the vented air. There are three main types of filter:

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Kitchen hood

Start with the simplest possible case. Write down what Kitchen hood claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Kitchen hood before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Kitchen hood ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Kitchen hood

In research: Kitchen hood appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Kitchen hood in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Kitchen hood is common in secondary-school and first-year university syllabi. It links to neighbouring topics Air filters, Home appliances, Indoor air pollution, so understanding it makes those chapters shorter.
In everyday life: Look for Kitchen hood outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Kitchen hood in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Kitchen hood means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Kitchen hood out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Kitchen hood in simple terms?

Why does Kitchen hood matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Kitchen hood?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Kitchen hood.