Do Thermcouples need to be physically touching?
Do Thermcouples need to be physically touching?
(OP)
Hi,
I have an application where I am using K Type Thermocouple probes to measure bearing temperatures in a gearbox, the probes are fed down straight bores into the gearbox to the bearings.
However.. I was a bit of a numpty, the depth I required was 142mm but once I include the glands the 150mm long probes I ordered shrink to a useful depth of 129mm.
Now, with a 13mm gap between the probe end and the bearing will this enable me to make sufficient measurements of the bearing temperature?
Bear in mind that once the gland is tightened the probe will be essentially in a sealed chamber.
Thanks in advance.
Cheers
Steve
I have an application where I am using K Type Thermocouple probes to measure bearing temperatures in a gearbox, the probes are fed down straight bores into the gearbox to the bearings.
However.. I was a bit of a numpty, the depth I required was 142mm but once I include the glands the 150mm long probes I ordered shrink to a useful depth of 129mm.
Now, with a 13mm gap between the probe end and the bearing will this enable me to make sufficient measurements of the bearing temperature?
Bear in mind that once the gland is tightened the probe will be essentially in a sealed chamber.
Thanks in advance.
Cheers
Steve





RE: Do Thermcouples need to be physically touching?
Congratulations on your new oil temperature gauge installation.
STF
RE: Do Thermcouples need to be physically touching?
Can you force a 14mm long thermosetting-but-thermo-conducting epoxy or material firmly and with very, very good contact into the base of the thermowell as a plug or filler?
RE: Do Thermcouples need to be physically touching?
Mike Halloran
Pembroke Pines, FL, USA
RE: Do Thermcouples need to be physically touching?
As to whether this thermocouple arrangement is adequate, it depends on what you intend to use these temp measurements for. If all you require is a record of the relative change in temperature for the test conditions, then your existing setup may work OK. But if you require precise temperature measurements at the bearing race surface, then you'll want to purchase a correct length thermocouple.
Just one additional comment about measuring bearing temperatures at the outside race surface, if possible take 2 measurements with one located in the direction of load on the race, and one located 180deg opposite. With a fixed outer race and a fixed load direction in respect to the outer race, the loaded sector of the outer race will normally run at higher temperatures.
RE: Do Thermcouples need to be physically touching?
Cheers
Steve
RE: Do Thermcouples need to be physically touching?
The bearing manufacturers want good protection for their bearings, so would likely recommend the tip touch the outside of the bearing race directly for best response and accuracy