TIPS ON PUMPING GAS
Only buy or fill up your vehicle in the early morning when the ground temperature is still cold. Remember that all service stations have their storage tanks buried below ground. The colder the ground the more dense the gasoline. When it gets warmer gasoline expands so when buying in the afternoon or in the evening your gallon is not exactly a gallon. In the petroleum business the specific gravity and temperature of the gasoline, diesel, jet fuel, ethanol and other petroleum products plays an important role.
A one degree rise in temperature is a big deal for this business but service stations do not have temperature compensation at the pumps. When you’re filling up do not squeeze the trigger of the nozzle to a fast mode. If you look you will see that the trigger has three (3) stages; low, middle, and high. In slow mode you should be pumping on low speed thereby minimizing the vapors that are created while you are pumping. Most hoses at the pump have a vapor return. If you are pumping on the fast rate some of the liquid that goes to your tank becomes vapor. Those vapors are being sucked up and back into the underground storage tank so you're getting less product for your money.
One of the most important tips is to fill up when your gas tank is HALF FULL or HALF EMPTY. The reason for this is the more gas you have in your tank the less air occupying its empty space. Gasoline evaporates faster than you can imagine. Gasoline storage tanks have an internal floating roof. This roof serves as zero clearance between the gas and the atmosphere so it minimizes the evaporation. Unlike service stations, trucks are temperature compensated so that every gallon is actually the exact amount. Another reminder, if there is a gasoline truck pumping into the storage tanks when you stop to buy gas DO NOT fill up. Most likely the gasoline is being stirred up as the gas is being delivered and you might pick up some of the dirt that normally settles on the bottom. Hopefully, these tips will help you get the most value for your money.