What is a Temperature Calibrator Used for?

A temperature calibrator is a device used to determine a temperature sensor’s performance within specified limits of uncertainty or accuracy. There are different types of temperature calibration which are categorized into simulators and physical temperature sources.

Temperature Sensor Simulators

Different types of temperature sensor simulators include:

Benchtop Temperature Sensor Simulator and a Multi-function Calibrator

A benchtop simulator is designed for laboratory calibration purposes. They are more accurate and have more measurement functions than a portable simulator.

The benchtop-style simulator has several other calibration output signals, so they can be used for calibrating and testing electrical measuring devices like a hand-held multi-meter (electrical calibrators or multi-function calibrators).

Portable Temperature Sensor Simulators and Documented Process Calibrators

Portable temperature sensors are used for on-site work for checking temperature sensor circuits such as 4-20 Ma transmitter systems, oven displays, and programmable logic controller (PLC) systems. The documenting process calibrators (DPC) are more powerful portable simulators. They have more software options and features designed for factory process calibration needs.

Physical temperature sources

These can be classified as dry-block (dry-well) calibrators, furnaces or ovens, temperature baths, infrared calibrators, and temperature fixed points.

Dry Block Temperature Calibrator

As its name suggests, a dry-block calibrator does not require fluid to perform calibration. These calibrators cool or heat a metal block into which the device under test (DUT), like a temperature probe or sensor, is inserted. It includes an internal sensor and a readout screen that shows the temperature against which DUT is compared.

If a lower uncertainty is required, a reference thermometer can be inserted in a dry-block calibrator with enough measurement wells. Some dry-block calibrators are equipped with a built-in read-out and a reference thermometer input. Therefore, no external thermometer readout is needed for lower uncertainty measurements. The calibrator will then read out the screen and display both temperatures for comparison during the calibration process.

A thermocouple furnace is a type of dry–block calibrator that is rated for the highest temperatures (> 500 degrees) hence the name “thermocouple.” Another type of dry-block calibrator is known as a metrology well.

Metrology wells offer the highest accuracy within the solid-block calibrator family. It utilizes zone-controlled heaters that provide better axial and radial specifications than atypical drywall.

The advantage of a dry block calibrator over a simulator is that the dry block provides a true temperature calibration of the sensor. Fluke calibration is a device for precision calibration devices, temperature, humidity, pressure, and flow measurements.

Temperature bath calibrator

These use a stirred fluid in a tank as a transfer medium to perform calibration. Different fluids may be required depending on the application and calibration temperature range.

The temperature of the bath is built-in, but most are designed to use an external thermometer system in order to accurately measure fluid bath temperature. Temperature baths are more accurate when used with external reference than dry blocks.

Temperature controller calibration

Temperature-generating equipment is equipped with temperature controllers, most of which are digital. Temperature controllers are not stand-alone device, as it is generated as part of a system. They are mostly found on equipment like ovens, incubators, dryers, etc.

Temperature controller makes temperature very stable by giving suitable temperature standards because of its feedback mechanism in a closed loop circuit. To control a certain temperature, a temperature controller needs a temperature sensor, the most commonly used sensors are thermocouple wires.

The temperature transmitter is an electronic device that sends temperature measurements over two wires to the processing unit into more readable signals during the calibration process.

Procedure temperature controller

There are various ways that a temperature controller can be calibrated.

1. Temperature calibration is simulated using a calibrator such as the Fluke 754 and a thermocouple wire, where a temperature source is an electrical signal.

2. The second method involves the use of a bath, either dry or wet. In this bath, the sensing device is dipped into a hole in the bath to measure the actual temperature.

3. By comparing its reading to a more accurate thermometer or temperature indicator with a separate sensor. Sensors are clamped, inserted, or fastened by screws to the heat source or heating element.

4. By simulated voltage in MV, resistance in RTD, and a current of 4-20MA, depending on the settings or programming of the temperature controller, the fourth method is applied.

5. By measuring the temperature directly inside an enclosed system using a different indicator and sensor and then comparing its display with the temperature controller.

The best results in terms of accuracy and stabilization time occur when the probe can be inserted into stirred liquid.

Procedural thermometer calibration

A metal pointer on a circular scale indicates desired temperature measurements during the dial thermometer calibration process. How a dial thermometer works depends on the type of thermometer. Digital thermometers are is used to determine body temperature. These digital thermometers provide accurate readings in about a minute or less.

Digital thermometer applies optimized algorithms to precisely check temperature through oral and rectal measurements. Digital thermometer calibration follows strict steps to be accurate.