Parts of a Fuel Dispenser – Labeled Gas Pump Diagram

All 12 parts on the diagram

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Outside 7

Display Three windows: sale total, volume, and price for one gallon or liter.
Card reader With it a driver can pay without going into the store.
Nozzle boot The nozzle hangs here between sales.
Nozzle Squeezing its lever lets the fuel flow. A valve in it shuts by itself when the tank is full.
Swivel A turning joint fitted into the base of the nozzle. The hose is joined to it.
Hose A dispenser may have one hose or several.
Breakaway A coupling near the dispenser end of the hose. When it pulls apart, its valve stops the fuel.

Lower cabinet, door off 5

Shear valve It sits under the dispenser, where the supply pipe comes up. One section is made to break on a hard knock, and the valve then closes.
Filter A canister changed for a new one when the fuel flow slows.
Meter The fuel pushes its pistons as it passes. They turn a shaft.
Pulser Sends electrical pulses to the computer in the head. The computer counts them to work out the volume.
Solenoid valve An electric coil opens and closes it.

How this list was compiled: Every name checked on 2026-09-30 and kept only where at least two independent sources use it: (1) Wikipedia, text only: Gasoline pump; (2) a dispenser maker's installation and maintenance manual, full text at https://archive.org/details/manualzilla-id-7251506; (3) a second maker's start-up and service manual, full text at https://archive.org/details/manualzilla-id-6039291. The manuals were read for the names of parts and what each does. No fuel brand or maker is named or drawn. Licence: own work

The drawing: Drawn for this site on 2026-09-30 from plain geometry; no maker's product, nothing traced. Licence: own work

How it works

The parts of a fuel dispenser, the machine most drivers call a gas pump. The first drawing is what a driver sees. The second takes the door off the lower cabinet to show what measures the fuel.

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What you see, then what measures the fuel

Numbers 1 and 2 are on the head: the display and the card reader. Numbers 3 to 7 are what you handle: the nozzle in its boot, the swivel, the hose and the breakaway. Numbers 8 to 12 follow the fuel up through the cabinet: the shear valve under the island, the filter, the meter with the pulser on top, and the solenoid valve.

The breakaway is at the dispenser end of the hose; the swivel is at the nozzle end.
The meter measures; the pulser only reports what the meter did.

Questions and answers

What are the parts of a fuel dispenser called?

The head holds the display and the card reader. The nozzle hangs in the nozzle boot, joined through a swivel to the hose, which has a breakaway. Inside are the meter and pulser, a filter, solenoid valves, and a shear valve under the dispenser.

How does a gas pump know how much fuel it has pumped?

A meter in the lower cabinet measures the fuel as it passes. The pulser turns the meter's movement into electrical pulses, and the computer in the head counts them and shows the volume and the price on the display.

Where is the pump in a gas pump?

Often not in it at all. At many stations the pump is sealed inside the storage tank underground, and what stands on the island is a dispenser that measures and controls the fuel.

What happens if you drive off with the nozzle still in the tank?

The breakaway on the hose comes apart. The nozzle and hose stay with the car, and a valve in the breakaway stops the flow of fuel.