biology

Olfactometer

Olfactometer is a biology 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 Olfactometer rather than just read about it. In short: An olfactometer is an instrument used to detect and measure odor dilution. Olfactometers are used in conjunction with human subjects in laboratory settings, most often in market research, to quantify and qualify human olfaction.

Key takeaways

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

Reference excerpt

An olfactometer is an instrument used to detect and measure odor dilution. Olfactometers are used in conjunction with human subjects in laboratory settings, most often in market research, to quantify and qualify human olfaction. Olfactometers are used to gauge the odor detection threshold of substances. To measure intensity, olfactometers introduce an odorous gas as a baseline against which other odors are compared. Many scientists use the term "olfactometer" to refer to a device used to study insect behavior in presence of an olfactory stimulus. It consists of a tube with a bifurcation (with "T" or "Y" shape) where an insect walks and decides between two choices, usually clean air versus air carrying an odor. This is why this device is also called dual choice olfactometer. Alternatively, an olfactometer is a device used for producing aromas in a precise and controlled manner.

Flow-olfactometer

Description According to Lindstrom et al, continuous flow olfactometers enable very fast onset and offset timing, thereby creating a nice, square-shaped stimulus presentation. In these designs, air flows continuously through or over the odor source and is then transported via tubing to the subject. Vacuum pressure plays an important role in a continuous flow olfactometer, where it is utilized both to switch between odorized air flow and control flow and to evacuate odors, often just below the subject’s nose.

How a flow-olfactometer works A flow-olfactometer produces a constant heated and humidified flow of pure air. This air flow runs continuously to the subjects nose. For the length of the stimulus pulse the continuous air flow is replaced by a block of odorized air.

Dynamic dilution olfactometer The new generations of dynamic dilution olfactometers quantify odors using a panel and can allow different complementary techniques: odor concentration and odor threshold determination, odor suprathreshold determination with comparison to a reference gas, hedonic scale assessment to determine the degree of appreciation, evaluation of the relative intensity of odors, and allow training and automatic evaluation of expert panels. The most recognised olfactometry standard is currently the EN13725 standard. Analyses performed by olfactometers are often used in site diagnostics (multiple odor sources) performed with the goal of establishing odor management plans.

Field olfactometry Field olfactometry can be a useful tool in validating odor complaints, or determining odor levels for various locations. Field olfactometers provide the same basic function of a laboratory olfactometer but are designed to be used by a single panelist to measure ambient odors. To be classified as a field olfactometer the device must be able to provide accurate and controlled dilution of the ambient air with odorless air and present the diluted sample to the panelist at controlled and positive air flow. The Nasal Ranger, developed by St. Croix Sensory, is a common brand of field olfactometer used in wastewater treatment plants, industrial facilities, and marijuana grow houses.

Verifying odorant level in natural gas Natural gas odorant concentrations are required to be readily detectable at one-fifth of the lower flammable limit of the gas by state and federal regulation. Many gas companies utilize olfactometers to verify this standard. The ASTM has published a standard test method for this determination.

See also Electronic nose Electrogustometry Machine olfaction

References

CEN 13725:2003 - Air quality - Determination of odour concentration by dynamic olfactometry; German version EN 13725:2003.

Illustrations

Worked examples

Example 1 — a first encounter with Olfactometer

Start with the simplest possible case. Write down what Olfactometer claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, 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 Olfactometer 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 Olfactometer 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 Olfactometer

In research: Olfactometer appears in biology 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 Olfactometer 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: Olfactometer is common in secondary-school and first-year university syllabi. It links to neighbouring topics Neurophysiology, Olfaction, Sensors, so understanding it makes those chapters shorter.
In everyday life: Look for Olfactometer 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 Olfactometer in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Olfactometer 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 Olfactometer out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Olfactometer in simple terms?

Why does Olfactometer matter?

Because it connects several biology 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 Olfactometer?

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 Olfactometer.