DID YOU KNOW?
Fuel vapor becomes most hazardous at the tank—not at the outlet where flow meters are typically installed.
Understanding Why FLOMEC Oval Gear, OM Series, Flow Meters Use Zone Certification
How fuel vapor behavior shapes safety requirements in hazardous locations
Fuel vapors, not liquid fuel, create the real ignition risk, which is why the OM Series is engineered specifically for Class I, Zone 1 installations.
"Did You Know?"
Gasoline vapor, not liquid fuel, drives the need for Zone certification.
Liquid gasoline doesn’t actually burn—it must first evaporate into a vapor. When gasoline vapor mixes with air, it creates an ignitable mixture. Inside a fuel tank, this vapor is at its most explosive state. Once vented into the atmosphere, it becomes less concentrated and less combustible. The farther the vapor travels from its source, the less hazardous it becomes. This principle is why Great Plains Industries selected “Zone” FM Approval for the FLOMEC OM Series Flameproof meters instead of the traditional “Division” FM Approval.
Flow meters for fuel are rarely installed inside the fuel tank because doing so would require the highest explosion-proof safety measures—an extremely costly and impractical approach. Instead, meters are typically installed near the tank outlet. Designing the OM Series for Division 1 FM Approval would essentially be equivalent to designing for Zone 0, which is overkill for this application. Zone 1 certification allows safe installation right where fuel exits the tank—without the expense of designing for inside-the-tank conditions.
This is just one example of a Class I, Zone 1 application. Other common Zone 1 environments include:
- Chemical processing plants where solvents and flammable liquids are handled
- Oil and gas refineries near pumps, valves, and transfer points
- Paint and coating facilities where vapors are present during normal operations
- Pharmaceutical manufacturing using volatile chemicals
- Fuel loading and unloading stations at terminals and depots
- Marine and offshore platforms where hydrocarbons are processed
FLOMEC OM Series Flameproof Certifications
FLOMEC offers oval gear meters with two North American Flameproof FM certifications:
- Class I, Zone 1, AEx db IIB T4 Gb Ta = -40°C to +120°C (U.S. Standards)
- Class I, Zone 1, Ex db IIB T4 Gb Ta = -40°C to +120°C (Canadian Standards)
These certifications apply to OM Series meters with the following specifications:
- Line Sizes: 1/8”, 1/4”, 3/8”, ½”, 1”, 1-1/2”, 2”, 3”, and 4”
- Body Materials: Aluminum and Stainless Steel
- Rotor Materials: PPS and Stainless Steel; standard or high-viscosity (keishi cut)
- Process Fittings: ANSI-150 Flange, NPT, BSPP, Tri-clamp, ANSI-300 Flange, PN16 DIN Flange, and No Fitting (manifold)
- Electrical Entry: ½” NPT and M20 x 1.5mm