Thermometers measure temperature. They consist of two main parts: the sensor and the display. The sensor measures the temperature, and the display shows the user the temperature in a numerical value. Display options include digital and analog.
Thermometers come in a variety of styles and sizes to meet a range of needs. They are used in a variety of applications, including heating and cooling, appliances, aircraft, agriculture, food and beverage, and many more. The different types of thermometers have unique features that make them more effective and easier to use. For instance, aquarium thermometers feature waterproof technology. When choosing a thermometer, it is important to consider how it will be used.
Types of Thermometers
- Food and Beverage
- Industrial Controls
- PC Board Burn-in
- Paper production
- Household use
- Measuring differential temperature
- General monitoring of environment in plants, buildings, warehouses, silos, and storages
- IAQ monitoring and ventilation control
- Measuring temperature in frozen solids and liquids
- Measuring temperature on surfaces such as grills and motors
- Troubleshooting heating and cooling systems, motors, generators, and ventilation systems
- Contact Thermometers. Contact thermometers measure the temperatures of materials by coming into direct contact with the object. They can be used to measure a variety of objects, and they are available in a range of styles and sizes to meet various needs.
- Analog Thermometers: A dial gauge is durable, easy to read, and requires no batteries. They consist of a glass lens, stainless steel probe, and dial gauge.
- Digital Thermometers: The clear digital displays on digital thermometers are easier to read than traditional analog thermometers. They come in a variety of styles and sizes to meet a range of needs.
- Infrared Thermometers. Infrared thermometers are non-contact thermometers that calculate temperature based on the amount of thermal radiation emitted by the measured object. They come in a variety of styles and sizes to meet a range of needs. Common styles are gun-style IR thermometers, food grade IR thermometers, and visual IR thermometers. Some models include temperature probe options for contact readings.
Contact thermometers measure the temperatures of materials by coming into direct contact with the object. These thermometers feature a temperature probe and display. They can be used to measure a variety of objects, and they are available in a range of styles and sizes to meet various needs.
Configurations of Contact Thermometers to Consider
- Data Logging Digital Thermometers. These digital thermometers store data and record it for future reference and analyzing. Many are compatible with Windows Software, and they are capable of storing thousands of data entries. Data logging thermometers are frequently used in laboratories, audits, and industrial control situations for measuring differential temperature.
- Waterproof Keypad Thermometers. These thermometers are used for applications where the thermometer may come in contact with water or other liquids, such as measuring temperatures in aquariums. The digital thermometers often include multiple mounting options such as suction cup or Velcro mounting tape.
- Wireless Thermometers. Wireless thermometers are used to monitor and measure indoor and outdoor temperatures. They include a remote wireless sensor and base station. Key features include memory and programmable alerts. These thermometers are often CE and ROHS approved.
- Wall Mounted Thermometers. Wall mounted thermometers are used for indoor and outdoor applications and sometimes monitor additional parameters such as humidity and IAQ. Some also feature a carbon dioxide alarm.
- Stem Thermometers. Stem thermometers are ideal for Food Preparation, Household Use, Manufacturing, Photography, Hobbyists, Automotive Repair, Heating and Refrigeration. They come in a variety of styles and sizes, such as corkscrew stem and T-Bar stem. These digital thermometers are capable of measuring extremely cold as well as extremely hot temperatures. Waterproof options are available.
- Flat Surface Stem Dial Thermometer. These thermometers measure temperatures on flat surfaces such as grills and motors. They can be used in liquids, semi-solids, and solids. They are perfect for measuring temperatures in HVAC applications, such as air ducts, vents, and heaters.
- Infrared Thermometers. Some non-contact IR thermometers can also be used as contact thermometers. They come with temperature probes for contact readings.
Temperature probes are metal thermometers used to measure the temperature of a specific environment, such as a piece of meat or a liquid. They are often used in food preparations and laboratories. Many accessories are available, and they come in a variety of styles and sizes to meet a range of needs. T-handle temperature probes make it easier to hold while jabbing. Bead type temperature probes can be snaked around objects. Half-pipe shaped temperature probes fit around the circumference of pipes. When choosing a temperature probe, it is important to consider how the device will be used.
Find these accessory probes here: Products > Accessories > Probes > Temperature Probes
High Accuracy Secondary Thermometers vs. Primary Contact Thermometers
There are two main types of thermometers: primary and secondary. Which category the thermometer fits in depends on how the temperature measurement is calculated.
The most common type is high accuracy secondary thermometers. They are widely used because of their convenience and accuracy. These types of thermometers must be calibrated against a primary thermometer.
Primary thermometers are more complex than secondary thermometers. These thermometers calculate temperature without any unknown quantities because the measured matter is so well known. For instance, these thermometers may be based on the equation of the state of a gas, on the velocity of sound in a gas, on the thermal noise, or other complex equations.
Key Features of Contact Thermometers to Consider
- LED back light
- Multiple channel input
- Auto Range
- RS-232 Interface
- Windows Software
- Data Logging
- Auto Power Off
- HOLD Function
- Displays ambient and remote temperature
- Min/Max temperature memory
- High/Low temperature alarm
- °F and °C selectable
- Up to three wireless sensors may be used with base station
- Additional sensors available
- Jumbo display
- Food Safe Stainless Steel Probe
- Instant Read
- Flat-edge, anti-roll design
- Fold up probe adjusts from 0° to 180° for best measurement and viewing angle
- Temperature differential: T1-T2
- Compatible with Popular Types K, J, T, E and/or R thermocouples
- Includes Certificate of Traceable Calibration
- ROHS, CE, and WEEE approved
- Meets GMPs and HACCP requirements set by the FDA
- Relative time clock on MIN, MAX, and AVG provides a time reference for major events
- Dual temperature for easy Super-Heat and Sub-Cool calculations
Infrared thermometers calculate temperature based on the amount of thermal radiation emitted by the measured object. They come in a variety of styles and sizes to meet a range of needs. IR Thermometers are used by HVACR technicians, electricians, plumbers, building inspectors, manufacturing technicians, food processing inspectors, and homeowners. Common styles are gun-style IR thermometers, food grade IR thermometers, and visual IR thermometers. Some models include temperature probe options for contact readings.
IR Thermometer Applications
Types of Infrared Thermometers
- Detecting hot spots in mechanical equipment, electrical circuit boxes, or outlets
- Checking heater temperature for calibration and control purposes
- Checking oven temperature for calibration and control purposes
- Checking for hot spots in firefighting situations
- Monitoring materials during heating and cooling processes
- Research and development
- Manufacturing quality control situations
- Heat Loss Energy Audits
- Measuring and logging food temperatures during cooking, serving, cooling, storage, transport, and reheating
- IR "Gun" Thermometers. These use a laser to help aim the thermometer. They come in a gun-style and are non-contact thermometers. They are a good way to determine hidden hot and cold spots from a distance or up close. They are also good for measuring moving objects. Pocket size options are available
This video demonstrates the Extech 42511 Dual Laser Infrared Thermometer. It is just one style of IR gun-style thermometers available. It features adjustable emissivity, audible alarm alerts, and more.
- Food Grade IR Thermometers. Food Grade IR thermometers meet GMPs and HACCP requirements set by the FDA. They are used to ensure food safety, quality, and consistency by measuring and logging food temperatures during cooking, serving, cooling, storage, transport, and reheating
- Visual IR Thermometer. Visual IR Thermometers combine the convenience of a spot thermometer with the visual advantage of a thermal imager, creating a brand new tool category. They feature a troubleshooting camera with infrared heat map that instantly identifies the exact location of the problem
This video demonstrates the Fluke VT02 Visual IR Thermometer. It works by taking a visual image and applying a thermal heat map.
Choosing an IR Thermometer
- Field of View (FOV) / Distance-to-Spot ratio (D:S). The field of view is essential to obtaining an accurate temperature reading. The target being measured should completely fill the field of view of the instrument. A measurement error can occur if the background temperature is different from the object temperature. This is why distance to spot ratio is important when selecting an IR thermometer.
The distance-to-spot ratio (D:S) is the ratio of the distance to the object and the diameter of the temperature measurement area. The larger the ratio number is the better the instrument's resolution, and the smaller the spot size that can be measured. For instance, an IR thermometer with 50:1 ratio will accurately measure temperatures of smaller objects than an IR thermometer with a 10:1 ratio. If the D:S ratio is 10:1, measurement of an object 10 inches (25.4 cm) away will average the temperature over a 1 inch (25 mm) diameter area. A ratio of 50:1 will measure a 1 inch (25mm) diameter area that is 50 inches (127 cm) away. When selecting an IR thermometer consider the distance from the target to be measured and select a model with an appropriate distance-to-spot ratio.
||A practical illustration of how significant a measurement error can be when measuring a hot pipe if spot size is too big
- Temperature Range. When selecting an IR thermometer, a wide temperature range is important. Since these thermometers are used in applications with very high and very low temperatures, the thermometer must be able to accurately measure these temperatures. This is especially important in food and beverage applications as well as applications that measure frozen materials.
- Adjustable Emissivity. Emissivity is the ratio of energy radiated (invisible heat) by a material to the energy radiated by a black body at the same temperature. It is the only type of heat that can be used to measure the surface temperature of an object. Reflected and transmitted heat cannot be used.
However, IR thermometers recognize reflected, transmitted, and emitted heat, so the device must be adjusted to read only emitted heat in order to provide a surface temperature. A black body will have emissivity of 1 and objects will have a value between 0 and 1. Emissivity of common objects is generally available in the IR thermometer instruction manual or on the internet. Better IR thermometers have adjustable emissivity settings. Others have a pre-set emissivity of 0.95. For better results with these 0.95 fixed models, use emissivity tape, available from TEquipment, on the surface to be measured. To learn more about emissivity tape, see the section "What is Non-Reflective Tape for IR Thermometers (Emissivity Tape)?" below.
Additional Features of IR Thermometers to Consider
- Data Capture. When selecting an IR thermometer, look at the data logging features. Many store dozens of reads and feature connectivity options that allow for easy recording and analyzing. This makes the user’s job easier and more efficient.
What is Non-Reflective Tape for IR Thermometers (Emissivity Tape)?
- Fast response time
- Dual laser targeting system helps approximate the target spot size
- Large backlit LCD
- Automatic temperature "hold" when the trigger is released
- Display and backlight turn off after 15 seconds of inactivity
- Auto-power off after 60 seconds of inactivity
- °F and °C selectable
- Thermocouple port
- Min/Max. modes
- High and Low temperature alarm
- Differential and Average Temperature functions
- Low battery indication
- Includes Certificate of Traceable Calibration
- ROHS, CE, and WEEE approved
- Meets GMPs and HACCP requirements set by the FDA.
- HACCP check lights for instant recognition of safe/unsafe temperatures
- Countdown timer to monitor cooking, cooling and HACCP exposure times
- Velcro pipe probe for superheat, sub-cooling or other contact and ambient measurements
- Easily trend and analyze data with included software
- See your data right away without leaving the site, using the USB and your laptop for "Hands-free" data logging
- Built-in fold-out probe for measuring internal food temperatures
- Quick hot and cold spot finders - available in visual, infrared and blended views
- Almost invisible penetration hole due to special food probe
This tape can be used with IR thermometers that have fixed emissivity rates to increase accuracy when measuring shiny objects. Simply place the tape on the object being measured and allow time for it to reach the same temperature as the object. Use the taped spot as the measuring spot.
Spot Thermometer vs Thermal Imaging Camera
Consider a Thermal Imaging Camera instead of an spot IR thermometer. Prices of thermal imaging cameras are falling and capabilities increasing. Here is a link for comparison of the technologies:
Spot Thermometer vs Thermal Imaging Camera
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