Which Sensor should i use

[karmax]

Hello,
       We have a machine in which a big vertical bubble makes in which gas is filled .Bubble temperature is around 70-80 degree Celsius.Bubble always move vertical continuously through another machine. Some time due to hole in bubble some gas comes out so size of bubble decreases and afterwards some one has to refill gas inside it.I want to automate this all task.

I tried using Sonar it works good in room but as i installed that sonar in machine .Sonar doesnot work may be due to heat generated by bubble.so i am looking some help in this sustem so that i can make a circuit which cut down gas when it fill upto a level and start filling when it goes low from a level so please guide me which sensor should i use and how can i do this.

[Razor Concepts]

Use a liquid level float sensor

they are commonly used in septic tanks, where when the tank gets full, it alerts the homeowner.