Tank truck are filled with product and then shipped to the customer. I need a reliable and adjustable high level switch that can be inserted in the top hatch and will shutoff fill based on level in the tank truck.
A lot depends on the product. If it is clean water it is easy. Just about any level switch will work.
My inclination is some kind of mechanical back pressure shut off valve like what is used with gas pumps. That way you don't need to hook up anything to the tanker that someone will forget..
What's the fluid? Something flammable or hazardous? Something sanitary like milk or potable water? Something that leaves sticky residue? Something viscous like molasses?
What and how does the switch perform shutoff? Interrupt a heavy electrical current? Mechanically stop the flow itself?
Adjustable level over what range?
Is this for one tank only or for a fleet of 100 identical tank trucks? Or 100 similar, but different tank trucks? Or for 100 different chemicals being carried on one tank truck?
Will the switch be permanently mounted? to what? How big can it be? How much space can it occupy? Will it be there during transit? If this about an electrical switch how will the wires get out of the tank?
Are you prepared to modify the tank for appropriate mechanical or electrical installation?
What codes does this switch addition have to meet?
Will the truck always be level and stationary when being filled?
Is electrical power available to power a switching device? at what voltage?
What kind of money are you willing to spend to fix whatever problem a switch might solve?
$10/truck? $100/truck? $1,000/truck? How big is the problem that it's worth solving with a whatever a 'switch' costs?
From what you describe something like an ultrasonic gap switch attached to the fill nozzle might work, no moving parts and could be well protected or how about something like a gasoline dispensing nozzle that actually closes the fill nozzle as Bob & Jim suggested.
