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The FE Petro STP-MLD leak normal static system pressure,three GPM.This is the indication to the <br /> detector is a three position,pressure- GPH(at 10 psi)is metered through the operator that a leak is present.If <br /> sensing,piston operated valve STP-MLD into the piping system.If a there are no leaks,pressure rapidly <br /> designed to continuously monitor the leak is present that equals or exceeds builds in the system forcing the <br /> piping by indicating any leakage in the this amount,as much product escapes STP-MLD to open to the full-flow <br /> piping between the discharge and the from the system as is metered through position.In a system with no leaks,it <br /> submersible pump and the solenoid the STP-MLD.Under this condition, takes approximately three seconds for <br /> valve in a service station dispenser. pressure cannot build up in the piping a complete test.No further line testing <br /> When the submerged pump is system.When a nozzle is opened,a takes place until the line pressure <br /> turned on after the system pressure poppet in the STP-MLD moves to a drops significantly below the normal <br /> has dropped significantly below the position that restricts the flow to 2 static system pressure. <br /> „rc <br /> 1. The Tripped or Bottom 2.Leak Sensing Position 3.Non-Leak or Full Flow <br /> Position In this position the system pressure Position <br /> When the system is less than 1 psi,the has increased to approximately 12 psi This position allows full flow.The <br /> piston and poppet are in the and all the flow must travel around poppet will remain in approximately <br /> "bottom"or"tripped"position.In this the metering pin which limits it to this position as long as the system <br /> position of the poppet,product flows approximately a 3 GPH rate(at 10 psi). pressure remains at about the <br /> through the horizontal hole in the pop- If there is a leak in the system which pumping pressure.If the pressure in <br /> pet and around the metering pin at a will allow leakage to exceed this amount, the system drops when the pump is <br /> rate of approximately 2 GPM the line pressure will not build beyond turned off,either due to thermal <br /> flow into the delivery line when the this point and the valve will remain in contraction of the product or due to a <br /> submersible pump is running.In the leak sensing position with the main leak,the piston moves downward and <br /> normal operations the piping remains flow blocked.If there is an attempt to the poppet engages and seals inside <br /> full of fluid and when the submersible dispense while the valve is in this posi- the cage at about 3 psi,or approxi- <br /> pump is turned on,with a flow rate of tion,the line pressure will drop to less mately 10 feet of head,in gasoline. <br /> 2 GPM through the poppet,pressure than 1 psi,the piston will respond,and Any time the pump is turned on after <br /> builds rapidly and the poppet moves to the poppet will return to Position 1 the seal on the poppet is inside the <br /> the leak sensing position. where 2 GPM will flow to the dispensers. cage,a line test will be performed. <br /> Leaks smaller than 3 GPH will be indi- <br /> cated by the STP-MLD taking longer <br /> than three seconds to open completely <br /> because some of the flow leaks out of <br /> the system and the rest builds pressure. _ <br /> If there is no leakage in the system, <br /> the small flow around the metering pin FE Petro,Inc.® 4805 Voges Road <br /> increases the line pressure and in P.O.Box 139 ® McFarland,WI 53558 <br /> approximately three seconds the piston (608)838-8786 ■ Fax:(608)838-6433 <br /> will move the poppet to Position 3. <br />