Thermal Switch identification

[Samuel43]

Hi,
I have this thermal switch from a Gemmy fog machine that I have had for a number of years. I recently rewired it and figured out in the process that the thermal switch in it is probably bad. It should read about 50mΩ when closed but when I disconnect it and test it with my meter it reads anywhere from 0.2 to several hundred Ohms. So obviously I should replace it, but I do not know the switching temperature of it. On the top ceramic part it is marked with "KSD301" which is just a generic part number. On the bottom surface it says "B240" and "CM". Does this mean a switching temperature of 240'C?

Thanks

 

[Bluejets]

Te KSD301 identifies it as a basic thermal switch.
The temperature is normally stamped on the bottom and relates to the degrees c temperature.
However this seems rather high but depends where in the device the sensor is located.
You say fogger so that kind of implys there is some type of water boiler which could likely get to those temperatures.

 

[Samuel43]

The idea with the fogger I have is that the KSD301 is attached to a metal plate that is connected to the heater, and when the heater is up to temperature, the switch opens which deactivates the heater. Then of course when the heater cools off enough the switch closes to restart the heater. The heater doesn't boil the liquid, but rather when the pump moves the fog fluid (water + glycerin) to the heater, it needs to be hot enough to immediately vaporize the fluid into fog. I just don't want to buy the wrong thermostat and have my machine overheat.

 

[Bluejets]

Usually these are meant for over temperature protection, not constant thermostat operation.
I've seen similar on many devices but a similar application to your may be the plastic laminators used in offices. On -Off cycles there would probably be in the vicinity of 2 to 3 minutes.
However, perhaps if you were to monitor the plate temperature and select a level which will do what you want without overheating.
That or get on to the manufacturer.

 

[Samuel43]

I did try contacting the manufacturer but they were not helpful.