Wahl 2500MX, Instruction Manual

Page: 15 / 56

11
Thermocouple Type K (Model TC830): For 2500°F (1370°C) with expendable type K
tips. Useful for molten non-ferrous metals. The meter is removable from the handle
and therefore can be used elsewhere with any of the other Wahl probes.
Thermocouple Type S (Model TC840):
For 3200°F (1770°C) in very high temperature
iron and steel melts. The quartz encased probe junction can usually be used more than
once. When broken or consumed, the tip is simply pulled out of the Dipstick tip and a
new one inserted. The tip is made with tight contact. Grasp the expendable tip by the
ceramic shoulder and push it hard into the holder.
CAUTION: The quartz tip breaks easily. Do not drop it or push on the quartz tip.
Three types of tips are available: Exposed ceramic tip for small dips of up to1-3/4 inch
immersion, and two types of tips with aluminum splash shield and 12-inch cardboard
shaft for penetration through slag up to 12 inch immersion.
3.1 Open Probe
If the thermocouple sensor loses continuity, or if no sensor is connected to the meter,
the display will show “-OL-”, indicating out-of-limit reading.
3.2 Temperature Sensors in Use
An understanding of heat transfer is needed for accurate field use of temperature
sensors. The sensor measures its own temperature. Therefore, to measure a body
temperature, it requires good contact with that body. In the case of liquids or gases,
good immersion and mixing are necessary.
A portable probe temperature sensor must have the following characteristics:
(a) A low thermal mass (product of its specific heat and weight).
(b) A large area for surface contact to permit heat transfer between the object
being measured and the probe sensor.
(c) A minimum of heat conduction away from the sensor which will reduce the
temperature below that of the object being measured and create an inaccuracy.