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VALVE OPERATION The Franklin Fueling Systems (FFS) Defender Series® Overfill Prevention Valve (OPV) is designed with a primary shutoff that activates between 85 and 92% of tank volume, depending on the tank diameter. When the primary shut-off is actuated, the flow through the OPV is limited to less than 8 GPM (30 LPM). A secondary, positive shutoff happens at 95% tank volume if you continue filling. After primary shutoff, you can still drain the delivery hose, but you must be extremely careful and follow these steps: 1. Close the truck bottom loading valve. 2. Wait 5 minutes. 3. Partially open the coupler between the delivery hose and the bottom loading valve and allow the hose to drain. NOTE: Shutoff points are affected by the specific gravity of the stored liquids. These instructions are based on the average performance of all products. The OPV was designed to be only an emergency overfill prevention device. NOTE: Determine if the underground storage tank has a ball float vent valve. If it does, make sure the nipple portion does not extend more than 3" (76.2 mm) into the tank. TANK SIZE AND INSTALLATION OF OVERFILL PREVENTION DEVICES In a two-stage, mechanical Overfill Prevention Valve (OPV), primary closure of the device significantly restricts the flow of fuel into the tank. After primary shut-off occurs, the delivery hose can be drained slowly 3-5 GPM (11-18 LPM) until secondary or "positive" shut-off occurs. Under current EPA regulations and industry standards, secondary shut-off is typically set at 95% of tank volume; however, other local regulations may prescribe other values. Mechanical OPVs use a float(s) to trigger shut-off, or closure, of the device and restrict flow to the storage tank. The shut-off level of the secondary ("positive") closure can be set based on the height of installation in the tank. The height of this installation typically is correlated with a volume percentage such as 95%. The level of the primary shut-off point will fluctuate to some degree based variables such as the: • Size and shape of the tank. (See the images below.) • Specific gravity of the stored liquid: The offset picture is based on a specific gravity of 0.75 for gasoline and 0.85 for diesel. A lower specific gravity will need more fluid to create equivalent buoyancy, which equates to a higher shutoff level (and vice -versa). • Flow rate during delivery. The offset is based off data from our production flow test apparatus, which runs at 370 gpm. A lower flowrate causes less buoyancy force needed to activate the primary, which equates to a lower shutoff level. The most influential of these variables is the size and shape of the tank volume, as illustrated below. Always use a calibrated tank chart in combination with the manufacturer's instructions for best results.