Defender Series® 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. The Defender Series® OPV provides safe, rapid, and reliable fuel drops with simple installation, service, and remote testing capability.


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  • Highlights


    Eliminate Leak Points

    The revolutionary magnetically-coupled actuator system allows the Defender Series® OPV to achieve positive shutoff without a single penetration in the valve body.

    • The absence of body penetrations in the OPV eliminates potential leak paths for escaping vapors.
    • Every unit is factory tested for 100% vapor tightness to ensure a clean, fugitive emission-free forecourt.
    • With increasing vapor recovery regulations around the world, the Defender Series™ OPV will have you ready for compliance.


    Simple Installation

    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.

    • 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.
    • A perfectly in-line assembly installs smoothly into the riser and can be easily removed for maintenance.
    • With threaded top and bottom drop tube installation, damaged drop tubes can easily be replaced without having to purchase an entirely new assembly.


    High or Low Flow

    Minimal flow path obstructions accommodate high flow drops while the magnetically-coupled actuator system also provides reliable positive shutoff for low flow drops.

    • The Defender Series® OPV accommodates a broad range of flow rates from 25 gpm to 370 gpm (95 lpm to 1,400 lpm).
    • 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.
    • In low flow applications, the actuator system will assist by kicking the flapper out into the flow of fuel to generate positive shutoff.


    Remote Testing

    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.

    • 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.
    • 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.
    • Fast visual inspection can be conducted by a single person.


    Completely Versatile

    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.

    • Each model is designed to meet all major approvals and global performance requirements.
    • Alcohol, gas, and biofuel (E-85, gasoline and biodiesel) compatible models come with hard coated anodized drop tubes for full compatibility.
    • For use in direct and remote gravity drop applications with models for coaxial applications.


    Additional Highlights

    • Magnetic coupler actuates the interior primary flapper assembly and secondary shut-off valve, eliminating valve body penetrations and any potential product or vapor leak points.
    • After cutting to length in the field, the upper drop tube is roll-crimped onto a top adapter outfitted with two O-rings and then threaded onto the top of the valve body, eliminating the need for drilling, rivets, epoxy, and flaring tools.
    • The roll-crimp/thread method of installing drop tubes ensures proper alignment of the drop tubes with the rest of the OPV assembly, making installation and removal of the entire assembly smooth.
    • Bottom drop tube is cut in the field and threaded onto the bottom of the valve ensuring straight installation.
    • Damaged drop tubes can be easily replaced instead of having to purchase an entire new assembly.
    • Fully compatible with gas, gas/alcohol blends, diesel and biodiesel.
    • Compatible with industry standard 4" drop tubes allowing retrofit into existing installations.
    • The entire OPV assembly remains within the 4" inner diameter of the riser preventing interference with other tank components and also allowing removal even while the tank is full.
    • Actuates in both low and high flow applications and functions within a broad range of flow rates from 95 lpm to 1,400 lpm (25 gpm to 370 gpm).
    • The remote testing tool allows for remote testing of the primary functionality without having to remove the OPV from the riser.

  • Order Info

    708691901Defender Series® overfill prevention valve with 5' (1524mm) top drop tube, 8' (2438mm) bottom drop tube, KIWA certified
    708691902Defender Series® overfill prevention valve with 5' (1524mm) top drop tube, 10' (3048mm) bottom drop tube, KIWA certified
    708692901Defender Series® overfill prevention valve with 10' (3048mm) top drop tube, 8' (2438mm) bottom drop tube, KIWA certified
    708692902Defender Series® overfill prevention valve with 10' (3048mm) top drop tube, 10' (3048mm) bottom drop tube, KIWA certified
    708694901Defender Series® overfill prevention valve only with top and bottom adapter, AGB compatible, KIWA certified
    708556901Defender Series® remote fill splice kit
    708535901Roll crimping tool
    708530930Replacement roll crimper tool roller bit for retrofit with existing tool
    708534901Remote 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.
  • Specs


    • EN13616 certified
    • KIWA BRL-K636/03 certified
    • ATEX 2014/34/UE approved



    • 1. Pre-flanged aluminum top drop tube
    • 2. Roll-crimped top fitting/drop tube
    • 3. Protective float sleeve
    • 4. Float (shielded by float sleeve)
    • 5. Valve Assembly
    • 6. Magnetically-coupled actuator
    • 7. Threaded bottom drop tube


    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). 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.

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