Marmonix MST-325 (MST325) Folding Probe Thermometer, NTC, −50 to +300 °C, IP67

The Marmonix MST-325 probe thermometer (also typed MST325 or MST 325) is a handheld contact thermometer whose metal probe swings out on a folding joint and reads from −50 to +300 °C (−58 to +572 °F) through an NTC sensor. Between −20 and +100 °C the datasheet tolerance is ±1.0 °C; below −20 °C it widens to ±2 °C, and above +100 °C it becomes ±1% of the reading. Readings step in tenths of a degree up to 199° and in whole degrees from 200°, a front key flips the unit between °C and °F, and the large display is illuminated for dim rooms. MAX, MIN and HOLD keep a value on screen, automatic power-off saves the two AAA cells (about 100 hours of typical use), and the IP67 rubber-coated housing can be washed under a running tap. The datasheet gives a compact size of 15 cm (5.9 in), and 250 × 56 × 24.5 mm with the probe folded out. See the Marmonix thermometers range, or the MT-40 single-use USB temperature data logger when a shipment needs a record of the whole journey rather than a spot reading.

Thermometer Probe MST325

Thermometer Probe MST-325 is a waterproof folding thermometer that offers handy, practical, and strong support when carrying out temperature measurements. The MST-325 is ideally suited to core temperature measurement thanks to a robust metal folding joint and a long, stable measurement probe. The thermometer features IP67 class protection and can be used under all conditions.

MST-325 can also be easily cleaned under running water and has a rubber-coated surface for non-slip handling. The thermometer has a large, illuminated display for easy and error-free viewing of measurement data under poor lighting conditions.

MST325 Features

Key features of the MST-325 include:

• Wide range: -50 to +300˚C (-58 to 572˚F)
• MAX, MIN, and HOLD modes
• Automatic Power Off
• Compact 5.9” size (15cm)
• IP67 waterproof Protection
• Non-slip rubber-coated surface
• Ideally suited to core temperature measurements
• The large, illuminated readout display
• HACCP approved

Thermometer Probe MST325 specifications:

Case study: reading the accuracy band before signing a kitchen temperature log

A catering kitchen takes three readings each morning with one MST-325: the centre of a chilled delivery at goods-in, a frozen item from the freezer, and the frying oil before service. The probe covers all three, but the datasheet tolerance is not the same for each, so the supervisor notes the band next to every limit:

• Chilled delivery at about +4 °C: this sits in the −20 to +100 °C band, so the value is good to ±1.0 °C and is displayed in 0.1° steps.
• Frozen stock at about −18 °C: still inside the ±1.0 °C band. The datasheet rates the meter itself for 0 to +60 °C operation, so the item is probed at the freezer door instead of leaving the thermometer inside.
• Frying oil at about 180 °C: above +100 °C the tolerance is ±1% of the reading, roughly ±1.8 °C here, and the display still shows tenths; from 200° it changes to whole degrees.

HOLD freezes each value so it can be written down after the probe is pulled out, and the thermometer is rinsed under the tap before it goes back in the apron pocket.

MST-325 thermometer: what buyers ask

How accurate is the MST-325 near its top range?

From +100 to +300 °C the datasheet tolerance is ±1% of the reading, which works out to about ±2 °C at 200 °C and ±3 °C at 300 °C. Between −20 and +100 °C it is ±1.0 °C, and from −50 to −20 °C it is ±2 °C.

Can the MST-325 be washed?

Yes. The housing is rated IP67, the datasheet says it can be cleaned under running water, and the rubber coating stops it slipping in wet hands.

What comes with the MST-325, and what powers it?

The datasheet lists a battery and a user’s manual in the package. The thermometer runs on two AAA cells, rated for about 100 hours of typical use, and switches itself off automatically.