Defender Series® Overfill Prevention Valve

An overfill prevention valve stops a gravity delivery from a road tanker before the underground tank is overfilled. The Defender Series OPV does this with a magnetically coupled actuator: the float rises outside the valve and moves the internal flapper through magnets, so the valve body has no penetrations at all for vapour or product to escape through.

Shutoff happens in two stages. The primary shutoff acts between 85% and 92% of tank volume, depending on tank diameter, and cuts flow to under 30 lpm (8 gpm). If filling continues, a secondary positive shutoff closes at 95% of tank volume. The actuator holds the flapper back during high-flow drops and pushes it into the stream during low-flow drops, so the valve works across 95 to 1,400 lpm (25 to 370 gpm).

Installation uses a roll-crimp and thread method: the top drop tube is cut to length, roll-crimped onto a double O-ring adapter and threaded to the valve, and the bottom tube threads on underneath, with no drilling, rivets, epoxy or flaring. A damaged tube can be replaced on its own. The whole assembly stays within the 4" riser bore, so it can be removed even with a full tank, and a sectional testing tool up to 11 ft (3.35 m) long lets one person confirm the primary function from grade without pulling the valve. Versions cover direct, remote and coaxial drops, and AGB versions with hard-anodised tubes handle E85 and biodiesel. The valve is ATEX 2014/34/EU approved, EN13616 certified and KIWA BRL-K636/03 certified. Apex supplies, installs and tests Defender OPVs.