How Does A Gas Nozzle Know When To Stop?

Have you ever been pumping gas in your car, and all of a sudden? ssh, it just shuts off in your hand. Maybe it takes a finger off that kind of thing.

Image Credit: Google

How does the gas nozzle know when to switch off? Well, We are here to explain. It's actually surprisingly complicated. Have you ever heard of the Venturi effect? If you take a tube and you pitch it in the middle, then fluid--and remember, fluid can be gas. It can be liquid. It doesn't just have to be water or something. After the pinch, after it goes through the bit, it becomes compressed. And as its velocity speeds up, the pressure on the other side of the tube actually decreases. Keep in mind that it’s the Venturi Effect. 

Venturi Effect, Credit: Google

If you look at a gas nozzle, you'll see a little hole toward the end. The hole actually leads to a tube. And that tube runs all the way up the length of the gas nozzle. And it usually tees off. On one side, you've got a Venturi tube. On the other side, you've got a tube leading to a diaphragm of air. Now that diaphragm of air is all blown up nice and big, while there's air running through the nozzle sensor. So while you're pumping gas, and gas is in the tank, and you're still filling it up, the air is moving through this little sensor pipe quite nicely. The pressure on one end of the Venturi tube, which is on this side, is nice and low. And on the other side, the diaphragm is nice and puffed up. But as the gas starts to rise, maybe it starts to foam, or it starts just simply to fill up the tank. 

That sensor, that pipe, starts to suck up gas. And when the gas is sucked up, the density of a gas is a lot heavier than the density of air. The Venturi tube suddenly changes in pressure, which creates suction on the other end of this pipe, which sucks the diaphragm, which collapses a little bit, triggering an automatic shut-off. Seriously, that's what's going on in the gas nozzle when you're pumping gas and it fills up. That's how it knows your tank is full. So I guess maybe ruminate on this. Chew on it. Think about it for possibly the rest of your life. It is really complex but pretty cool. It's not magic, I guess is what I'm trying to say. I'm sure you like this topic. There are tons of other ones. If you have a question that you wanted us to answer, you can leave it in the comments section below. Like us. Subscribe to us.