Thermometers

Thermometers are vital pieces of test and measure equipment that are designed to measure temperature across all sectors and industries. Here at Cromwell, we have a range of thermometers available to ensure you have the best instruments to allow you to accurately measure temperature from leading brands such as Brannan, Digitron, Fluke, and Oxford.

What are thermometers?

Thermometers are scientific instruments that have been designed for the purpose of measuring the temperature or the temperature gradients of an object and displaying an accurate reading most commonly using the metric of celsius (°C) or fahrenheit (°F) but some can also output in the measurement in kelvin (K). Thermometers work by using two key elements - a sensor to measure the temperature, and a method of converting this into a numerical value. Different types of thermometer achieve this in different ways, although overall the two types of temperature thermometers measure are:
• Contact   -   must make contact with the object/person.
• Non-contact   -   (remote) - no contact needed.

Why thermometers?

The need to be able to measure temperature accurately is a crucial factor in all areas of everyday life. Thermometers have been developed to test the degree of hotness or coldness of an object and display the measurement on gauge or digital display that can be interpreted by the user.

When are thermometers used?

Thermometers are widely used measurement gauges, with the thermometer selection type dependant on the specific environments or application it is being used for:
• Indoors/outdoors settings
• Domestic   -   everyday use at home, garden, health/illness detection, or temperature control of thermostats and appliances.
• Workplaces/commercial environments   -   to ensure temperature poses no risk to the safety of the workforce.
• Manufacturing   -   temperature monitoring of equipment/sensitive raw materials.
• Food industry   -   food storage safety/food production
• Health & safety   -   to adhere to food hygiene test and regulations
• Medical healthcare facilities      hospitals/doctors surgeries/ covid detection.
• Water tanks   -   industrial maintenance.
• Heating & ventilation   -   thermostats/air cooling system.
• Scientific research   -   controlled environments/laboratories.
• Transportation   -   temperature control of ambient and freezer compartments.
• Inspection tools   -   cold or hot spots/air leak detection.
• Temperature range control   -   air conditioning/controlled refrigeration

Thermometer types

There are a huge range of thermometers available in different shapes, sizes and designs to suit the specific task of the operator:
• Digital thermometers   -   are designed for ease of use, often lightweight and portable, with an easy to read digital display that usually outputs both celsius and fahrenheit metrics. They work by using a probe to accurately measure the temperature and display an instant digital reading. The internal sensors of a digital thermometer can detect changes in the resistance, current or voltage - which are grouped in three types: resistance temperature detectors (RTD), thermocouple or thermistor and are more accurate than traditional mercury thermometers.
• Infrared (IR) thermometers   -    also known as laser thermometers or temperature guns, temperature is calculated by measuring thermal radiation using a contactless method that allows temperature to be calculated from a distance. They are able to provide fast, highly accurate readings and some are capable of keeping storable readings for repeatable measurements. Depending on the design, infrared thermometers can operate using both a single or double laser beam and can be operated in a wide temperature range.
• Probe thermometers   -    often called penetration thermometers they are predominantly used in the food industry. The design consists of a thin stainless steel rod (probe) that is connected to a digital readout that precisely displays the real time temperature. Probes can be inserted into foods or submerged in liquids to display temperatures; some can be programmed to sound an alarm once desired temperature has been reached, they are also used in other settings to monitor and measure surface or air temperature.
• Wireless thermometers   -   ideal for a variety of applications. They usually have a sensor that can be used to measure both indoor and outdoor temperatures, often used in domestic environments, greenhouses and garden areas. They are also used as data loggers that record and store a large number of readings.
• Fixed wall thermometers   -    are thermometers that are fixed in a desired location that allow for a quick handsfree reading in settings such as food production areas or temperature-critical environments.
• Glass thermometers   -    also known as mercury thermometer or liquid in glass thermometers, are the most recognised type of thermometer that uses a glass tube that contains a bulb filled with mercury (typically red or silver ) that raises up the marked scales and indicates temperature. Highly versatile as require no need for power to operate.

Considerations when choosing a thermometers

• Metric   -   not all thermometers output the temperature reading in the same metrics, consider the unit of measure you require when selecting your thermometer.
• Type   -   the type of thermometer selection will be dependant of the environment or object you intend to use it for.
• Temperature range   -   all thermometers have a minimum and maximum temperature range that they are able to operate in, consider this at selection.
• Accuracy   -   each thermometer device has an accuracy rating that it is able to perform within, this should be considered as some thermometers will not be suitable for specific tasks.

Thermometers jargon buster

Here at Cromwell, we want to make sure that you make a confident purchasing decision, so we've outlined and explained some key terms to help you shop our range of thermometers with ease.

What does calibrating your thermometer mean?

Calibration is the process of checking the accuracy of your product and making necessary adjustments if it isn't reading correctly. Thermometers should be calibrated against another thermometer to check the accuracy. The easiest way to calibrate a contact thermometer is by using the freezing point or ice point method, whereby the thermometer is plunged into icy cold water and read without touching the sides of the container.

FAQs

How long will a digital thermometer last?

There is no set expiry date for digital thermometers, however it is advised they be replaced approximately every 3 to 5 years.

Which type of thermometer is best to be used at home?

The digital thermometer is the most accurate way to measure body temperature at home and to detect a fever. There are several different thermometer types that each obtain a reading from a specific location on the body, these include oral, ear, forehead, and multifunctional models that are capable of obtaining a temperature reading from multiple locations.

What is the difference between a medical and laboratory thermometer?

A medical thermometer is intended for measuring the temperature of a human body and it designed to be easy to clean and keep sterile. Laboratory thermometers are used for measuring all other temperature types in controlled test environments.