08-11-2014, 09:04 AM
There are two systems traditionally used in the industrial world.
1) "Immersion" type probe with a high temp thermocouple on the probe - usually type K or type S. You need a thermocouple readout with the proper calibration setting to use the probe. This system works well on small furnaces (such as home shop) where the operator can safely approach the furnace opening. The probes are considered disposable. When the probe eventually fails you replace it with a new one. You want a probe that is 2-3 feet long to keep your hand back from the heat. In today's electronics world, people like Fluke make relatively inexpensive readout devices.
2) "Optical" type telescopes. Intended for use with large furnaces where the operator must stand back 20 -30 feet to take safely the reading. (But can also be used on small, shop furnaces). These are non-contact devices that use a small telescope. You look through the telescope at the hot metal. You are also looking past the filament of a small light bulb in the field of view. You adjust a knob which regulates the current flow through the light bulb until the filament "disappears." At this point the filament temp = metal temp. The knob is calibrated in temperature. These instruments were designed for the steel industry and were ruggedly built. You can find used versions on Ebay for not much money. "Pryo" is one brand. "Leeds and Northrup" is another.
Terry S.
1) "Immersion" type probe with a high temp thermocouple on the probe - usually type K or type S. You need a thermocouple readout with the proper calibration setting to use the probe. This system works well on small furnaces (such as home shop) where the operator can safely approach the furnace opening. The probes are considered disposable. When the probe eventually fails you replace it with a new one. You want a probe that is 2-3 feet long to keep your hand back from the heat. In today's electronics world, people like Fluke make relatively inexpensive readout devices.
2) "Optical" type telescopes. Intended for use with large furnaces where the operator must stand back 20 -30 feet to take safely the reading. (But can also be used on small, shop furnaces). These are non-contact devices that use a small telescope. You look through the telescope at the hot metal. You are also looking past the filament of a small light bulb in the field of view. You adjust a knob which regulates the current flow through the light bulb until the filament "disappears." At this point the filament temp = metal temp. The knob is calibrated in temperature. These instruments were designed for the steel industry and were ruggedly built. You can find used versions on Ebay for not much money. "Pryo" is one brand. "Leeds and Northrup" is another.
Terry S.