"The Stopper" threads into the fill opening and is an integral part of the fill tube. The OPW 61ƒSTOP is fully adjustable to allow for easy installation in new or existing aboveground tanks of various heights and storage capacities.
The Stopper is a single-action, complete shut-off valve. When the liquid level rises to your specific, pre-determined tank capacity, the valve mechanism is released and automatically closes with the flow of the product. Any excess product left between the valve and the fuel delivery coupler is drained into the tank through internal drain vents. The drain vents on the 61fSTOP act as an anti-siphon, by introducing air/vapor into the fill line, to help isolate the tank from a potential siphon due to a broken or leaking fill pipe.
The 61ƒSTOP, available in either 2" or 3" full-flow models, maximizes flow rates and minimizes delivery times. The 2" 61ƒSTOP requires a 4" tank opening and minimum tank ullage (space from the top of the stored product to the inside top of the tank) of 8" on the 61ƒSTOP-1000 Cylindrical Float model and a minimum ullage of 4" on the 61ƒSTOP-2000 Float Arm model. The61ƒSTOP-1000, with the cylindrical float, eliminates the need to position the valve to avoid tank walls or cross-bracing. The 61ƒSTOP-2000 with the float arm allows for increased usable storage capacity in the tank, and is well-suited for small capacity rectangular ASTs. The 3" 61ƒSTOP requires a 6" tank opening and incorporates a cylindrical float requiring 8" of tank ullage space. The 3" Stopper is a high-flow unit that can accommodate flow rates over 400 gallons per minute (depending on pump capacity).
The 61ƒSTOP-100M and -200M are anodized and compatible with 100% methanol or ethanol fuels. The OPW 61ƒSTOP-305A meets with the specifications of the Handbook of Aviation Fuels Properties for Aviation/Jet Fuel Compatibility (as developed by the Coordinating Research Council of the Society of Automotive Engineers). The 61ƒSTOP-305A is compatible with aviation fuels (including jet fuels), gasoline, gasoline–alcohol fuels, diesel, kerosene, mogas, fuel oil, motor oils (up to 60W) and anti-freeze.