Guardian 5000 Temperature Probe

Quick Answer: The Guardian 5000 Temperature Probe is an external sensor that plugs into a Guardian 5000 hotplate or hotplate stirrer and is placed in the sample, so the unit regulates its heating from the liquid temperature rather than from the top-plate setting.

Plate Temperature vs Sample Temperature

A hotplate on its own controls how hot its top plate is. The liquid in a beaker on that plate is always cooler, by an amount that depends on vessel size, volume, stirring and room air. For work that needs a known sample temperature, such as dissolving a reagent at a set value or holding an enzyme buffer steady, that gap is a problem. An external probe closes the loop: the unit reads the liquid directly and adjusts the heating until the sample, not the plate, reaches the setpoint.

The Guardian 5000 range from OHAUS offers this external probe control. When the probe is connected, the hotplate typically heats harder at first and then eases off as the liquid approaches the setpoint, which reduces overshoot compared with guessing a plate setting.

This listing has no photograph, and it does not state the probe’s sheath material, length or connector. Confirm those three details before ordering, especially if the liquids you heat are corrosive.

Specifications

Applications

• Holding a buffer or culture medium at a set temperature while it is stirred
• Heating a solution to a defined temperature for a solubility or kinetics practical
• Reducing overshoot when heating small volumes on a powerful hotplate
• Monitoring the temperature of a flask in a heating block

Care & Handling

• Mount the probe with a clamp on the Guardian rod so it cannot fall out of the liquid
• Keep the probe tip clear of the stir bar and the vessel wall
• Keep the cable off the hot top plate
• Rinse and dry the probe after use and store it straight

Why Choose LabEquip

Guardian 5000 users order this probe when their work moves from rough heating to set sample temperatures. LabEquip can confirm the probe’s sheath and connector and quote it with a rod and clamp from our general lab products range; contact us with your Guardian model.

Frequently Asked Questions

Why use an external temperature probe on a Guardian 5000?

Without a probe the unit controls its top plate, not the sample. The probe lets the unit heat until the liquid itself reaches the setpoint, which is far more accurate.

Where should the probe sit in the liquid?

Submerge the tip well below the surface, above the stir bar and away from the vessel wall, so it reads the bulk temperature of the liquid.

What is the probe sheath made of?

The listing does not state it. Ask us to confirm the sheath material when you enquire if your liquids are acidic or corrosive, since that decides whether the probe is suitable.

Does the probe reduce temperature overshoot?

Generally yes. With a probe in the liquid, the unit eases its heating as the sample nears the setpoint instead of overheating the plate.

What happens if the probe is lifted out of the liquid?

It then reads air temperature, and the unit may keep heating hard. Always clamp the probe so it cannot slip out during a run.

Can the probe be used on other brands of hotplate?

It is listed for Guardian 5000 units. Connectors and sensor types differ between brands, so it should not be assumed to work elsewhere.

Last Updated: September 2026