Meter Types & Calibration Reference
Fuel dispenser meters are precision measuring devices that track volume dispensed for billing accuracy. Understanding meter types, calibration requirements, and troubleshooting is essential for compliance.
Standard Tolerance
+/- 6 cu in
per 5 gallons
Standard Flow Rate
8-12 GPM
retail dispenser
High-Flow Rate
20-35 GPM
truck fueling
Inspection Frequency
Annual
most states
T-Series
Prefix: T1
Applications
- -Retail gasoline
- -Standard diesel
- -Encore 500/700
Calibration Method
Electronic adjustment via dispenser menu
Notes
Current production meter. Most common in field. Electronic pulser included.
T-Series High-Flow
Prefix: T2
Applications
- -Truck diesel
- -Fleet fueling
- -NP700 models
Calibration Method
Electronic adjustment via dispenser menu
Notes
High-flow variant for commercial applications. Larger ports and internal passages.
M-Series (Legacy)
Prefix: M0
Applications
- -Encore 300
- -Legacy Highline
- -Pre-2005 dispensers
Calibration Method
Mechanical adjustment screw
Notes
Discontinued. Replacement parts available but consider T-Series upgrade.
WM-Series
Prefix: WM
Applications
- -Vista
- -Helix
- -Ovation retail
Calibration Method
Electronic adjustment via iGEM menu
Notes
Standard Wayne meter. Compatible across Vista/Helix/Ovation platforms.
WM-Series High-Flow
Prefix: WM-H
Applications
- -Ovation HD
- -Commercial diesel
- -Truck lanes
Calibration Method
Electronic adjustment via iGEM menu
Notes
High-flow for truck fueling. Requires high-flow hanging hardware.
Tokheim/Bennett Legacy
Prefix: Various
Applications
- -Older Tokheim
- -Bennett Pacific
- -Legacy sites
Calibration Method
Varies by model
Notes
Third-party or legacy meters. May require specialized service.
Frequently Asked Questions
How often do fuel dispenser meters need calibration?
Calibration frequency depends on state requirements. Oklahoma and Kansas require annual inspections. Texas requires biennial (every 2 years). Most states follow NIST Handbook 44 which allows +/- 6 cubic inches per 5 gallons tolerance. Random inspections may occur anytime.
What is the difference between Gilbarco T-Series and M-Series meters?
T-Series is the current production Gilbarco meter with electronic pulser and improved accuracy. M-Series is the legacy design with mechanical adjustment, used in Encore 300 and older dispensers. M-Series is being phased out but replacement parts are still available. T-Series can replace M-Series with an adapter kit.
What is a high-flow meter used for?
High-flow meters (20-35 GPM) are used for commercial truck fueling where standard retail meters (8-12 GPM) would be too slow. They have larger internal passages and ports (1" vs 3/4") and require matching high-flow hoses, nozzles, and breakaways.
What causes a fuel meter to read inaccurately?
Common causes include: calibration drift from normal wear, air in product lines causing false readings, worn seals allowing fuel bypass, debris causing drag on the measuring element, failing pulsers missing counts, or temperature compensation errors. Large calibration errors may indicate the need for meter replacement.
Who can legally calibrate fuel dispensers?
Calibration must be performed by state-licensed technicians or registered service companies. In Oklahoma, this is ODAFF licensed. In Texas, TDA registered. Breaking state seals without authorization can result in significant fines. After calibration, new state seals must be applied.