Thermocouples can be carefully removed and polished clean with #00 steel wool.
You do NOT clean a thermocouple. They are really inexpensive and when they are giving problems have a LMP / or Gas fitter replace it
To troubleshoot a pilot light thermocouple issue in a gas appliance, first ensure the pilot light is lit. If it goes out frequently, clean the thermocouple and pilot assembly. Check for any loose connections or a faulty thermocouple. If the issue persists, consider replacing the thermocouple.
It's not necessary to clean it. If by any chance you have a problem and THINK you need to clean it, it's more likely the thermocouple is acting up and needs to be replaced.
Control valves do go bad, but not that often. The tip of the thermocouple is in the flame? Holding the pilot button down long enough for it to heat? Sometimes the first time you light it, it takes a little longer for the thermocouple to work. Good clean connection on the valve end of the thermocouple? That's all I can come up with at the moment.
The output of the thermocouple is linear.
Yes, thermocouple is used in fridges !
To create a thermocouple one needs thermocouple wire, a means of spot welding the wire, and wire strippers. A thermocouple is used to measure temperature.
You should not paint a thermocouple.
The thermocouple keeps a gas pilot light burning.
is a thermocouple an active or passive transducer?-why?
Remove the pilot assembly from the furnace and clean it up. You need to be careful when putting it back on at the gas valve so as not to crossthread the screw. Take a thin wire and clean the pilot orifice, then use a brush or sandpaper on the thermocouple.
To test a thermocouple on a water heater, you can use a multimeter to measure the voltage output. Disconnect the thermocouple from the control unit and place the multimeter probes on the thermocouple terminals. A functioning thermocouple should produce a voltage reading within the expected range. If the reading is outside this range, the thermocouple may need to be replaced.