Liquid Level Controls for Metal Finishing Tanks
Type 1 is based on electric conductivity where 3-24V are connected to two prongs (Titanium, Hastelloy, Tantalum, 316 SS, Graphite) in the tank. If solution level gets too low, no current can pass through the prongs and the power to the heater is turned off. Type 1 can not be used in flammable solutions.
Type 2 is a float type. A float containing a magnetic switch will turn the power to the heater off. Type 2 is the choice for DI water tanks and Sodium Dichromate tanks.
Type 3 is an air purge level system. A tube is immersed in the liquid and air passes through. When the back pressure is removed due to low liquid level, the switch opens.
The toughest challenge for all of the above sensors is the crystalline build up created by solution that can happen in metal finishing tanks.
Most brands of immersion heaters have a cut off device. However, if it’s a single use cutoff it may not get replaced in a timely fashion. If it’s a resettable type you could be stressing the plastic tank lining each time the hot zone of the heater is exposed to open the device.
Type 1 liquid level probes
With our L-600 and L-600MR level safety control the probes mounted on the lip of the tank and trimmed 1/2” above the cold zone bracket of the heater, in the absences of liquid the control circuit opens heater circuit.