Overfill Prevention Valve
Overfill Prevention Valve
The Defender Series® overfill prevention valve (OPV) prevents the overfill of an underground storage tank during a gravity-fed product delivery. It employs a revolutionary magnetically-coupled actuator system to provide positive shutoff. This unique method of shutoff eliminates any penetrations in the valve, making it both vapor and leak tight.

NEXT-LEVEL OVERFILL PREVENTION
The Defender Series® OPV provides safe, rapid, and reliable fuel drops with simple installation, service, and remote testing capability. The secret to this game changer is its revolutionary magnetically-coupled actuator system. The design allows positive shutoff without a single penetration in the valve body, meaning no leak or vapor paths.

Fast visual inspection can be conducted by a single person in a matter of minutes. The magnetically-coupled actuator system along with the testing tool allows for primary functionality testing of the OPV without having to remove the entire assembly from the riser.

Remote Testing Tool
The remote testing tool will actuate the flapper when inserted down the drop tube and slid by the actuator - this is confirmed visually through a window in the tool.

Any Tank Size
To accommodate varying tank sizes, the testing tool handle is segmented into six sections for customization up to 11 feet (3.35 meters) in length.
Gone are the days flaring, riveting, and epoxying drop tubes on site. The Defender Series® OPV utilizes an error proof roll-crimp and thread installation method to achieve a perfectly in-line installation.

Top Adapter
A special, double O-ring top adapter is used to attach the drop tube for easy installation without any drilling, riveting, epoxy or flaring tools.

In-Line Assembly
A perfectly in-line assembly installs smoothly into the riser and can be easily removed for maintenance.

Threaded Connections
With threaded top and bottom drop tube installation, damaged drop tubes can easily be replaced without having to purchase an entirely new assembly.
The Defender Series® represents our most versatile offering of OPVs to date with more approvals and capabilities per model as well as simpler ordering options.
Approvals
Each model is designed to meet all major approvals and global performance requirements.
Fuel Compatibility
Alcohol, gas, and biofuel (E-85, gasoline and biodiesel) compatible models come with hard coated anodized drop tubes for full compatibility.
Drop Applications
For use in direct and remote gravity drop applications with models for coaxial applications.

Minimal flow path obstructions accommodate high flow drops while the magnetically-coupled actuator system also provides reliable positive shutoff for low flow drops.
Flow Rates
The Defender Series® OPV accommodates a broad range of flow rates from 25 gpm to 370 gpm (95 lpm to 1,400 lpm).
High Flow
In high flow applications, the actuator system will hold the flapper in place, only releasing it into the flow of fuel once the float has risen to generate positive shutoff.
Low Flow
In low flow applications, the actuator system will assist by kicking the flapper out into the flow of fuel to generate positive shutoff.
Components
- Pre-flanged aluminum top drop tube
- Roll-crimped top fitting/drop tube
- Protective float sleeve
- Float (shielded by float sleeve)
- Valve Assembly
- Magnetically-coupled actuator
- Threaded bottom drop tube

Dimensions

Operation
The OPV is designed with a primary shutoff that will activate between 85% and 92% of tank volume, depending on tank diameter. After the primary shutoff is actuated the flow through the valve is limited to less than 30 lpm 8 gpm (30 lpm). A secondary positive shutoff will occur at 95% tank volume if filling continues. As the liquid level in the UST approaches 95% capacity, the liquid level raises the float. As the float rises it actuates the external/internal magnetic couplers which release the flapper to be closed by the flow of product. As the float continues to rise, the internal mechanism pushes the flapper further into the product flow to allow actuation at high or low flow rates. This sudden reduction in flow caused by the primary flapper closing creates "line shock" to the fill hose which signals the delivery driver that the tank is nearing 95% capacity. As the float continues to rise to the 95% fill level, the secondary closes, completely stopping the flow of fuel.
Approvals/Certifications
- UL 2583 and ULc listed, MH21090
- ATEX approved
- CARB certified, VR-101 (FFS) and VR-102 (OPW®) listed
Defender Series® Overfill Prevention Valve UL
Model Number | Description |
---|---|
708591901 |
Defender Series™ overfill prevention valve with 5' (1524mm) top drop tube, 8' (2438mm) bottom drop tube |
708591902 |
Defender Series™ overfill prevention valve with 5' (1524mm) top drop tube, 10' (3048mm) bottom drop tube |
708591921 |
Defender Series™ overfill prevention valve with 5' (1524mm) top drop tube, 8' (2438mm) bottom drop tube, AGB compatible* |
708591922 |
Defender Series™ overfill prevention valve with 5' (1524mm) top drop tube, 10' (3048mm) bottom drop tube, AGB compatible |
708592901 |
Defender Series™ overfill prevention valve with 10' (3048mm) top drop tube, 8' (2438mm) bottom drop tube |
708592902 |
Defender Series™ overfill prevention valve with 10' (3048mm) top drop tube, 10' (3048mm) bottom drop tube |
708592921 | Defender Series™ overfill prevention valve with 10' (3048mm) top drop tube, 8' (2438mm) bottom drop tube, AGB compatible |
708592922 |
Defender Series™ overfill prevention valve with 10' (3048mm) top drop tube, 10' (3048mm) bottom drop tube, AGB compatible |
708593901 |
Defender Series™ overfill prevention valve, coaxial with 6.5' (1981mm) top drop tube, 8' (2438mm) bottom drop tube |
708593902 |
Defender Series™ overfill prevention valve, coaxial with 6.5' (1981mm) top drop tube, 10' (3048mm) bottom drop tube |
708593923 | Defender Series® overfill prevention valve, poppeted coaxial with 6.5' top drop tube, 8' bottom drop tube, AGB compatible* |
708593924 |
Defender Series™ overfill prevention valve, poppeted coaxial with 6.5' (1981mm) top drop tube, 10' (3048mm) bottom drop tube |
708594901 |
Defender Series™ overfill prevention valve only with top adapter, AGB compatible |
708594902 |
Defender Series™ overfill prevention valve only with coaxial top adapter, AGB compatible |
708535901 |
Roll crimping tool |
708530930 |
Replacement roll crimper tool roller bit for retrofit with existing tool |
708534901 |
Remote testing tool, 11' (3353mm) long sectional/collapsible |
708534902 |
Coaxial Defender OPV Remote Testing Tool |
- Alcohol, gas, biofuel compatible (E-85, gasoline and biodiesel) models come with hard coated anodized drop tubes for full compatibility.
Defender Series® Overfill Prevention Valve EN
Model Number | Description |
---|---|
708691901 |
Defender Series® overfill prevention valve with 5' (1524mm) top drop tube, 8' (2438mm) bottom drop tube, KIWA certified |
708691902 | Defender Series® overfill prevention valve with 5' (1524 mm) top drop tube, 10' (3048 mm) bottom drop tube, KIWA certified |
708692901 | Defender Series® overfill prevention valve with 10' (3048 mm) top drop tube, 8' (2438 mm) bottom drop tube, KIWA certified |
708692902 |
Defender Series® overfill prevention valve with 10' (3048mm) top drop tube, 10' (3048mm) bottom drop tube, KIWA certified |
708694901 |
Defender Series® overfill prevention valve only with top and bottom adapter, AGB compatible, KIWA certified |
708556901 | Defender Series® remote fill splice kit, includes splice and O-rings |
708535901 |
Roll crimping tool |
708530930 |
Replacement roll crimper tool roller bit for retrofit with existing tool |
708534901 |
Remote testing tool, 11' (3353mm) long sectional/collapsible |
- Alcohol, gas, biofuel compatible (E-85, gasoline and biodiesel) models come with hard coated anodized drop tubes for full compatibility.
Brochures
Title | Type | Size | |
---|---|---|---|
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FFS-0392 Defender Series OPV Datasheet.pdf | 3.83 MB | |
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FFS-0393 Defender Series Overfill Prevention Valve Brochure.pdf | 0.68 MB | |
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FFS-0559 CARB Certified Defender Series OPV Brochure.pdf | 0.79 MB | |
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FFS-0667 (EN) Defender Series OPV Datasheet.pdf | 4.26 MB | |
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FFS-0769 Defender Series OPV VR-102 Brochure.pdf | 2.44 MB |
Catalogs
Title | Type | Size | |
---|---|---|---|
![]() |
FFS-0158 (EN) Piping Containment-Service Station Hardware Catalogue.pdf | 15.72 MB | |
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FFS-0216 (UL) FFS Product Catalog.pdf | 20.25 MB |
Drawings
Title | Type | Size | |
---|---|---|---|
CD_SSH_708591902_001.stp | STP | 24.24 MB | |
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CD_SSH_7085909XX_001.pdf | 0.03 MB | |
CD_SSH_7085909XX_001.dwg | DWG | 0.4 MB | |
CD_SSH_9466G_001.dwg | DWG | 0.3 MB | |
![]() |
CD_SSH_9466G_001.pdf | 0.1 MB |