Types of thermometers and how they work

Types of thermometers

Clinical Thermometers, Laboratory Thermometers, and Digital Thermometers

Clinical Thermometers

These thermometers are used in hospitals, clinics, and also in the home. These thermometers will have a Kink.

Kink meaning in a thermometer – It is used to prevent mercury from falling back into the bulb immediately.

This is done for convenience for noting the temperature when the thermometer is taken out from the patient’s mouth.

The clinical thermometer has two scales on either side. One side is of the scale is Fahrenheit and another side is in Celsius.

Since Fahrenheit is more sensitive, for measuring the temperature of patients, only Fahrenheit is taken.

The temperature range of clinical thermometer is 35°C (94°F) to 42°F or 108°F.

Precaution while using the Clinical Thermometer

The thermometer should be kept clean before and after use and sanitized using an antiseptic solution.

Shake the thermometer a few times to make the mercury level down. The mercury level before usage must be 35°C (94°F).

Do not hold on to the thermometer bulb. Need the mercury level straight to your line of sight and take the reading. This is done for accuracy.

The thermometer is made of glass while is fragile, use it with care. It may break and may cause injuries. Do not keep the thermometer hot object or in direct sunlight.

Laboratory Thermometers

The Laboratory Thermometers are one which is used in industries, schools, or college labs. Laboratory Thermometer has a temperature range greater than the clinical thermometer.

As a result, the stem and bulb of the Laboratory are longer. The Laboratory Thermometer is used for industrial applications due to its wide temperature range.

There is no Kink in the Clinical thermometer. The temperature range of the clinical thermometer is -10°C to 110°C

Precautions while using a Laboratory Thermometer

Place the thermometer upright and do not tilt the thermometer. The reading is only taken when the bulb is surrounded by the substance from all sides.

Digital Thermometer

These day mercury thermometers are not used due to toxicity. As mercury is not easily disposable when the thermometer breaks.

The digital thermometer is currently widely used due to its simplicity. It uses an electronic sensor that accurately measures body temperature.

The digital thermometer is usually kept in the mouth, bottom, or under the armpit. It usually takes 30 seconds to note the readings.

Caution while using Thermometer

The clinical thermometer should not be used other than measuring body temperature.

As these thermometers are made to measure small temperatures, they will break due to thermal expansion and pressure created inside when exposed to high temperatures.

It should be kept in a cool place and it should not be used to measure hot substances such as boiling water, not to be kept in Sunlight, etc.

Scales of Thermometers

Celsius Scale

It is termed after Swedish Astronomer Anders Celsius in 1742. Before Anders Celsius, it was called Centigrade.

These thermometers use Centrigrade as Scale because these were calibrated from 0°C to 100°C such 0°C is Freezing point and 100°C as boiling point.

Centi means 100 and Gradus means Steps in Greek. Celsius is the most used unit of measurement

* * All the Notes in this blog, are referred from Tamil Nadu State Board Books and Samacheer Kalvi Books. Kindly check with the original Tamil Nadu state board books and Ncert Books.