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PEI/RP1200-17 0 rIL M1 Although the effectiveness of overfill prevention devices can be tested by attempting to overfill an underground storage tank (UST) with product and determining how well the device functions, this approach is not recommended. Any malfunction in the overfill prevention device could result in a product release that could result in a threat to public health and safety and environmental damage. Federal UST rules require that overfill prevention equipment automatically restrict flow or alert the transfer operator when the tank is no more than 90 percent full or shut off flow into a tank when it is no more than 95 percent full. Other alternatives to prevent overfills are the restriction of flow during a delivery 30 minutes prior to overfilling; alerting the operator 1 minute before overfilling may occur; or automatically shutting off flow into a tank so that none of the fittings located on top of the tank are exposed to product due to overfilling. The PEI Overfill, Release Detection and Release Prevention Equipment Testing Committee has written the recommended practices for automatic shutoff devices to reflect that the devices must be set to shut off flow when the tank is no more than 95 percent full, and flow restriction and overfill alarm devices must automatically restrict flow or alert the transfer operator when the tank is no more than 90 percent full. This approach reflects the more conservative application of the rules. 7.1.1 General. Automatic shutoff devices, sometimes called flappers or flapper valves, are an integral part of the drop tube assembly installed within the tank fill riser. They are designed to initially restrict and subsequently completely shut off flow when product has reached predetermined levels during a delivery. Automatic shutoff valves need to be properly positioned and operate freely to control flow and prevent tank overfills. 7.1.2 Purpose. The purpose of this inspection is to verify the automatic shutoff valve is installed properly, operates as designed and is set to com- pletely shut off flow when the tank is no more than 95 percent full. 7.1.3 Description of Inspection. After a pre- liminary inspection of the automatic shutoff instal- lation, the drop tube is removed from the tank. The automatic shutoff is checked for proper operation, and its placement is measured to verify that it is properly located to completely shut off flow when the tank is no more than 95 percent full. 7.1.4 Preparation. Refer to the tank manufac- turer's calibration chart for the capacity in gal- lons, the diameter and the volume of product with respect to product level. If the automatic shutoff device has a float that extends from the drop tube in the shutoff (closed) position, verify the proper orientation of the float mechanism. The float mechanism should be orient- ed away from any obstructions (ball float, submers- ible turbine pump [STP], tank wall, tank gauge probe, etc.) If the movement of the float mecha- nism is restricted, it will not function as designed. Use this procedure in conjunction with the manu- facturer's installation and maintenance instruc- tions. 7.1.5 Inspection Equipment. Test equipment shall include: • tools for removal of the drop tube; • tape measure; • tools for inspection of the automatic shutoff. 7.1.6 Inspection Procedure. 1. Remove the drop tube from the tank. 2. Visually inspect the automatic shut off valve and float mechanism for any damage or corrosion that inhibits the functionality of the device, and remove any debris and foreign objects. 3. Manually move the float mechanism to ensure it moves freely. 4. With the float mechanism in the shutoff (closed) position, visually inspect the drop tube and verify that the shutoff valve is released and will move into the product flow path. 5. If possible, verify that the bypass valve in the drop tube is open and free of blockage. 6. If problems with the shutoff valve are found and defective components need repair or replace- ment, notify the appropriate person.