Hi Temp Level Switch


Thread Starter

Daniel M.

Hi List

I need to give a Low Level Alarm in a closed rectangular recipient 2x1x1 m (aprox 7x3x3 feet) containg a NON-CONDUCTIVE liquid at 500 C (or 932 F). It should be top-mounted. Standard capacitive, conductive or float probes only reach 400 C. I can´t use gamma because of the cost), and I have doubts with bubbles tubes.
I will appreciate any suggestion
Does someone make a level switch for example with a termocouple? (sensing temp. difference beetwen liquid and upper atmosphere?)
Thanks in advance

Rajesh Mehta

Hi Daniel!

This is not a big problem if a secondary contact, as suggested in your query itself, is acceptable to you.

In fact, you can make one yourself by connecting a temperature indicator that accepts the thermocouple input (K type would be suitable for the temp. range mentioned). All you have to ensure is that the indicator has at least one set point (preferably front accessible) with contact output.

The things you need to take care are: the indicator to be suitable for field mounting, power supply source for this indicator and ambient temp. compensation to get higher accuracy.

Such an indicator would be available from any industrial electronics store in your area. Makes can vary depending on the geographical location.

Hope this is of help to you.

Hi Daniel,
What is the name of the liquid.
does it solidify on at ambient temp?( or can you specify what is the temp below which the liquid soidifies?).
Also what is the range of viscocity values of the liquid?
Your answer will help me to suggest solution.

Hi -
We build an (RVI) remote visual indicator that mounts to the side of a tank. It is cost effective, can have one or several remote adjustable switch points, safe visual indication is an option and more. If should do the job for you at a good price. (other terms - magnetic indication)

Also - we use a float - attached to a sliding rod. The rod runs inside a top mounted vertical tube with adjustable switch points. The unit is usually flange mounted.

We also can build and supply a T/C with most any type of insertion tube.

All this basic information is at:


Just look at the pdf brochure. The site has just changed servers - so some things might be missing.

Thanks Bob Hogg
Hi list.
Finally I will use the following sugestion: a high temp. window laterally mounted and a capacitive sensor outside it.

If such a window (up to 500 C) is not available, I will put (vertically) two t/c of different lenght (about 3 inches) and wire them differencially to a display with alarm. When the first t/c becomes free of liquid, deltaT will increase and this will launch the alarm.
Of course when both t/c are free of liquid the deltaT will be null, but we can manage this exception.

If someone has already used this arrangement, be kind and tell me!

Thanks to all
Daniel M.