What Is a Handheld Temperature Probe? Types and Selection Criteria
A handheld temperature probe is a sensor with a handle that is touched to or immersed at the measuring point and connected to a portable thermometer; it has a type K or PT100 element.
A handheld temperature probe is a temperature sensor with a handle that is held against the measuring point, immersed in a liquid or inserted into a material, and connected to a portable thermometer. In maintenance, quality control and commissioning it is used to measure on the spot at points with no fixed sensor, and to check the reading of a machine's fixed probe.
Types by sensing element
| Element | Measuring principle | Device it connects to |
|---|---|---|
| Type K thermocouple (NiCr-Ni) | A temperature-dependent mV voltage forms at the junction of two different alloys; wide, high temperature range | Thermometer with a type K thermocouple input |
| PT100 | The platinum element is 100 Ω at 0 °C and its resistance rises with temperature; stable measurement over a narrower range | Thermometer with a PT100 input |
A PT100 is not a thermocouple but a resistance thermometer; plugged into a thermocouple input it does not read correctly.
Types by tip
- Surface probe: Flat or spring-loaded tip; touched to surfaces such as pipes, motor housings and moulds.
- Immersion probe: Long, straight sheath; for liquids, baths and tanks.
- Penetration probe: Pointed tip; inserted into semi-solid materials.
- Air probe: Tip exposed or inside a perforated guard; for room and duct air.
The product names in our catalogue do not state the tip type; check the tip shape and length on the drawing on the product page.
Selection criteria
- Thermometer input: The probe's element type must match the device input; a type K input needs a type K probe, a PT100 input a PT100 probe.
- Measuring range: The product data gives -50…+1100 °C for the type K models and -50…+600 °C for the PT100 model. This range applies to the measuring zone of the metal sheath; the handle and cable must not be exposed to the measured temperature.
- Tip shape: Chosen for surface, liquid, penetration or air measurement. Measuring a surface with an immersion probe reads low because the contact area is small.
- Immersion length and diameter: In a liquid or a furnace the tip must reach far enough into the medium; some models in our catalogue list a 350 mm immersion length. A thin sheath responds faster, a thick sheath withstands knocks better.
- Connection plug: A thermocouple probe's plug must fit the thermometer socket and the thermocouple type; for extensions, use thermocouple plugs and sockets and compensation cable of the same type.
Common mistakes
- Using a type K probe while the thermometer is set to another type: A device set to type J, for example, shows a wrong value with a K probe.
- Reading before the value settles: Wait until the tip reaches the temperature of the medium.
- Holding a surface probe at an angle: If the tip does not sit fully on the surface, the reading comes out low.
- Using a handheld probe for fixed measurement: Points permanently fitted on a machine take bayonet, screw-in or head type probes.
Related standards
- IEC 60584-1: Voltage–temperature relationship and tolerances of thermocouples, including type K.
- IEC 60751: Industrial platinum resistance thermometers such as PT100 and their tolerance classes.
Handheld probes in the Welibaba catalogue
The Handheld Temperature Probes category has 9 active products, all from Isıso:
| Element | Measuring range (product data) | Models | Products |
|---|---|---|---|
| Type K (NiCr-Ni) | -50…+1100 °C | IWRN-01A, IWRN-02B, IWRNM-01, IWRNM-02, IWRNM-101, IWRNM-102A, IWRNM-207S, IWRNM-J102 | 8 |
| PT100 | -50…+600 °C | IWZP-J102 | 1 |
Plugs and sockets for connecting probes are in Thermocouple Plugs and Sockets (21 products), portable measuring devices in Digital Thermometers (10 products), and probes for fixed mounting in Temperature Probes.
Frequently asked questions
Should I buy a type K or a PT100 handheld probe?
Check your thermometer's input first. Type K is common for high temperatures and general maintenance measurements; PT100 is chosen where more stable measurement over a narrower range is needed, but it requires a device with a PT100 input.
How is a handheld probe connected to a thermometer?
A thermocouple probe connects with a thermocouple plug; the plug's type and size must fit the thermometer socket. A PT100 probe connects to the device's PT100 input as the manufacturer specifies.
Why does a surface temperature reading come out low?
When the tip does not make full contact with the surface, or the surrounding air cools the tip. Use a flat or spring-loaded surface probe, press the tip on squarely and wait until the value stabilises.
Can a handheld probe be fitted permanently to a machine?
No, a handheld probe is for portable measurement. For a permanent measuring point, choose a bayonet, screw-in or head type temperature probe.