Ohaus Guardian 7000 " Ceramic Top HotPlate Stirrer

Ohaus Guardian 7000 " Ceramic Top HotPlate Stirrer. Heating and stirring belong together because heating without stirring is heating unevenly.

The models differ by 7000 7"x7" 120V, 5000 10"x10" 120V, 5000 7"x7" 120V, 5000 7"x7" 230V, 7000 10"x10" 120V, 7000 10"x10" 230V and 1 more.

The top surface decides the work

A ceramic top resists acids, cleans easily and tolerates spills, which is why it is standard for chemistry. It also heats a little more slowly than metal. An aluminium top conducts heat faster and more evenly, and is the better choice for a heating block or a large flask, but it stains and corrodes where a ceramic top would not.

Set point is not sample temperature

The number on the display is the plate, not the liquid. The gap between them depends on the vessel, the volume and the room, and it can be tens of degrees. Where the sample's temperature is what matters, a probe in the liquid feeding back to the controller is the only honest way to run it.

Where it is used

• general chemistry laboratories
• sample preparation and digestion
• media and reagent preparation
• teaching laboratories

Practical note

A hot plate stays dangerously hot long after it is switched off and most have no way to show it; treat a cold-looking plate as hot until it is proven otherwise.

Supplied in 7 models.