Topping off?

Question

So let me get this straight. I have half a tank and I put in $10. Of course it won't fill it but i put the automatic shut off thing on. So when it gets to $9.70ish it clicks off. I shouldn't continue pumping till 10? Or I can? I don't understand the whole no topping off. Is it only for when you get a full tank of gas

Answer 1

the automatic shut off is for your protection...it shuts off just before you reach your designated amount so you can decide if you want to stop there, or go SLOWLY to the max you designated. It clearly prevents you from going OVER your max. Even when you don't set a max shutoff, there is a "spillback" feature that clicks off when you get near the top of your tank to prevent overflow. You can still SLOWLY pump more after that to get to a designated dollar or gallon amount.

Answer 2

The automatic shut off is not there to stop you from filling your tank. LOL! These guys kill me. Automatic shut off pumps were not designed to prevent explosions. They were designed to protect the ozone layer from gasoline vapors. That is why the nozzles are called Vapor Recovery Nozzles. They do have a valve in the spout that is designed to shut the pump down, but not to prevent a fillup. It is designed to prevent overspilling which releases vapors. And that sign that suggests you don't topoff is to protect the valve in the nozzle. If people top off enough times with that $600.00 nozzle, the valve fails, nozzle must be replaced, and the EPA gets ticked off. The only repair is to replace the nozzle. The valves were mandated because gas stations in the 70s were drilling a hole back into the top of the nozzle and putting the spout back in so after the fuel crossed the meter in the nozzle, 25% of it was being sucked back into the nozzle and returned to the tank in thr ground. That is why we have Weights and Measures checking pump calibration to this day, at random, nationwide. Back in the 70s a complaint was filed when someone put $35.00 worth of gas into a VW Beetle. When the pump was checked, a government official used a government mandated graduated 5 gallon can, and when it was filled to 5 gallons, the pump actually showed 15 gallons had gone through the pump meter. The other 10 gallons was sucked back through the hole that was found drilled into the nozzle internally. This led to laws on vapor recovery, and the valve is designed to prevent not only vapor escape, but also to prevent fuel from returning to the nozzle, that you have paid for. The suggestion against topping off is to protect that valve from damage. Hope this helps you understand. I worked for a foundry in the early 90s that made these nozzles for OPW, when vapor recovery technology was being perfected.

Answer 3

It's generally not a good idea to keep pumping past the automatic shutoff. Some pumps may malfunction and not shut off again, leading to a spill (happened to my fiancee), and you're likely dumping whatever extra you put in right back through the gas station's vapor recovery system.

If not having nice round numbers bugs you that much, get a credit card/check card to pay with so you don't have to carry change :)