Gas Pump and Dispenser

Understanding the Differences Between a Gas Pump and Dispenser

Posted on November 14, 2019

The terms gas pump and dispenser are often used to refer to the same piece of equipment, however, there is a distinction between how the two get gas from the tank to your customers.

Fuel is delivered to a vehicle either through a self-contained gas pump or through a dispenser. Whether it is a gas pump or dispenser you are thinking about installing, there are pros and cons. Understanding the differences between the two can help you make better business decisions for your station.

Storage Tanks

First and foremost, storage tanks store gasoline for service stations in underground tanks. There are at least two tanks at a station. Each tank can hold several thousand gallons of gas. As well as each tank will hold a different grade of gas.

Suction Pump and Submersible Pump

The difference between a gas pump and a gas dispenser is the way the fuel gets from the storage tank to the unit and ultimately to the customer. To understand the best option, it’s necessary to look into how they work. A gas pump uses a suction pump, while a dispenser uses a submersible pump.

What is a Suction Pump?

When a gas station has a self-contained gas pump, it gets the fuel from the underground tank by a suction line. When the self-contained pump is used, the fuel pump causes the fuel to be suctioned from the underground tank to that specific pump.

How Does a Suction Pump Work?

The suction pump works off the principle of unequal pressure. A pipe is inserted and a motor above fluid level removes enough air from the pipe to decrease the air pressure about the gasoline. The motor continues to remove air until the air pressure above the gasoline is lower than the air pressure pushing down on the gas outside the pipe. The weight of the surrounding air forces the gas inside the pipe upward. Even as gravity tries to pull it back down. When the air pressure inside the pipe is low enough, the gas climbs up into the aboveground dispenser.

What is a Submersible Pump?

Dispensers receive fuel through a fuel pump unit. The unit is a submersible pump that is located in the underground tank. It pushes fuel from the underground tank to a fuel delivery system, thus making it possible to feed several dispensers at once. Because it can feed to several dispensers at a time, this is a preferred system for most gas station owners.

How a Submersible Pump Works

The pump is submerged below the surface of the liquid, where a propeller-like device moves the fuel upward. This device is called an impeller. The slanted bladed push the liquid gas. The impeller can push liquid over longer vertical distances.

It is efficient as it can be submerged into any liquid without worry about wear or tear. It also uses less energy than other kinds of pumps.

The Value of the Check Valve

Once pumping is complete and the pump motor is turned off, the gas inside the pipe doesn’t fall back into the tank. It is held inside the pipe by a check valve. It is located above the gas inside the pipe and creates an airtight seal above the fluid. While the bottom of the pipe remains open, the check valve’s vacuum pressure holds the gas in place.

The check valve prevents wear and tear on the suction pump. For the customer, it keeps a supply of gas in the pipe and the wait time isn’t a problem. While the process isn’t over 15-20 seconds, it can seem like an eternity and that will not help your station’s customer loyalty.

Whether you are in the market for a gas pump and dispenser, Graffco Inc. can help you find an affordable option to purchase new or reconditioned equipment.