Reducer, vaporizer, regulator, converter, evaporator it is same name used in different places worldwide for autogas device which is changing liquid LPG gas from the tank stored in around 5bar to 15bar pressure  on the inlet

to vapour gas under stable pressure of 1-1.5bar on the outlet. This rapid pressure change converts LPG from liquid to vapour and cool down  dramatically vapourizer changing it to the brick of ice. To avoid that coolant is used to warm up gas pressure reducer and prevent it to get frozen. Switching over from petrol to LPG therefore should happen  only when reducer  temperature will rise at least 50-60 degrees Celsius (although many installers set up switching over pressure at around 25 degrees Celsius which is still fine but makes the rubber parts of the reducer wearing faster).  

To know what temperature of the reducer is and when it is safe to switch over to LPG temperature sensor is used. For KME Gold is not that obvious where to screw it in for the new unit that is why we present it on the pictures below. To put the temperature sensor you need to remove the screw between water/coolant elbows and screw the M5 temperature sensor in leaving metal plate holding water elbows on its place (do not remove it).