Dispenser Configurations & Terminology
Understanding fuel dispenser configuration notation (3+0, 3+1, 4+1), blending vs non-blending systems, and the critical difference between a dispenser and an STP.
Pump vs Dispenser - Know the Difference
Dispenser = The customer-facing unit (what most people incorrectly call a "pump").
STP (Submersible Turbine Pump) = The actual pump, located inside the underground storage tank, that pushes fuel up to dispensers.
Configuration Notation Decoder
Hoses Per Side
Number of individual hoses available to customers on each side of the dispenser.
Additional Products
Number of additional base products beyond the minimum for dispensed grades. A "0" indicates non-blending (each grade has dedicated line). A "1" typically indicates blending (two products create three grades).
3+0
3 hoses, 3 products, NO blending
Tanks needed: 3
3+1
3 hoses, 2 products, WITH blending (87+93=89)
Tanks needed: 2
4+1
4 hoses, 3 products (2 gas blend + diesel)
Tanks needed: 3
Common dispenser configurations and their typical applications. The X+Y notation indicates hoses per side (+) base products beyond minimum for non-blending.
| Config | Hoses | Grades | Blending | Use Case |
|---|---|---|---|---|
| 3+0 | 3 | 3 | No | Legacy stations, high-volume single-grade lanes Three hoses: Regular, Mid-Grade, Premium (dedicated lines) |
| 3+1 | 3 | 3 | Yes | Most common modern configuration Three hoses dispensing 3 grades via 2 products (87 + 93 blend for 89) |
| 4+0 | 4 | 4 | No | Stations with diesel + 3 gasoline grades Regular, Mid-Grade, Premium, and Diesel on dedicated lines |
| 4+1 | 4 | 4 | Yes | Full-service stations, truck stops 3 gasoline grades (blended) + 1 diesel |
| 5+1 | 5 | 5 | Yes | Specialty stations (E85, racing fuel) Regular, Mid, Premium, Diesel, E85 |
| 2+0 | 2 | 2 | No | Small rural stations, marinas Regular gasoline and diesel only |
| 1+0 | 1 | 1 | No | Fleet fueling, DEF dispensers, specialty fuel Single product (diesel fleet, kerosene, DEF) |
Most Common Configuration: 3+1
The 3+1 configuration is the industry standard for modern retail stations. It provides 3 gasoline grades (Regular, Mid, Premium) using only 2 underground tanks. Regular (87 octane) and Premium (93 octane) are blended at the dispenser to create Mid-Grade (89 octane), reducing infrastructure costs significantly.
Frequently Asked Questions
What is the difference between a fuel pump and a dispenser?
A dispenser is the customer-facing unit where you select grade and dispense fuel into your vehicle. The actual pump (STP - Submersible Turbine Pump) is located inside the underground storage tank and pushes fuel up to the dispenser. What most people call a "pump" is technically a dispenser.
What does 3+1 dispenser configuration mean?
A 3+1 configuration means 3 hoses per side dispensing fuel from 2 base products through blending. The "+1" indicates one additional product beyond minimum for non-blending. Regular (87) and Premium (93) are blended to create Mid-Grade (89), reducing tank requirements from 3 to 2.
What is a blending dispenser?
A blending dispenser mixes two base fuel products (typically 87 octane Regular and 93 octane Premium) in precise ratios to create mid-grade fuel (89 octane). This reduces the number of underground storage tanks needed from 3 to 2 for a 3-grade gasoline offering.
How do fuel dispensers measure gallons accurately?
Dispensers use precision flow meters inside the unit that measure exact volumes. These meters must be calibrated to state tolerances (typically +/- 6 cubic inches per 5 gallons). Pulsers convert mechanical rotation to electrical signals for the electronic display.
What happens when an STP fails?
When a Submersible Turbine Pump (STP) fails, all dispensers connected to that product line will stop dispensing. In a pressure system, the STP is the only pump for that product - there is no backup. The tank must be accessed to replace the STP.