Liquid Level Detection To Shut Off Fuel Pump

HELP! I'm looking for advice or parts to problem solve a prototype.

The goal is to fill a clear cylinder closed top vessel (such as a clear pickle jar with a lid on top) with liquid through a valve in the bottom of the vessel; filled with an electrical pump. Pump and valve not the problem.

Vessel could be coupled with the pumping station either empty, or any amount of liquid other than full level; pump actuates when seated together....

Problems to solve are:

1.) Turning on the pump when the two are coupled

2.) HOW to immediately and automatically shut the pump off when vessel has reached maximum fill level.

Possible solutions #2 are: retro reflective sensor, direct infrared optical sensor or, most useful, would be a pressure type switch that is connected to the fuel flow line that immediately detects that the vessel is at full capacity and therefore shuts off the pump.

Any suggestions?
Thanks for your help.

What about the air trapped in the top of the vessel?

Sounds serious! How quickly does your pump stop pumping when the power is removed? Is there any backflow through the pump at the time it is turned off?


Float switch

Agreed. Sounds like a job for a float switch.

Your thread title mentions "fuel". That means it is combustible. That also means that the "air" that vents out the small hole is not "air" at all, but a mixture of air and "fuel" vapors". In a short time of operation the space will be filled with the fuel/air mixture. How does you system currently handle this?

Also, by never mentioning the chemical that makes up the "fuel", there can never be a way to pick or design any sensor that will be exposed to the "fuel".

I think you are asking, like many others, for free design help for a commercial product and this forum is not going to give free help.

Good luck,