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■he FE Petro STP-MLD leak normal static system pressure,three GPM.This is the indication to the ) detector is a three position,pressure- GPH(at 10 psi)is metered through the operator that a leak is present.If sensing,piston operated valve STP-MLD into the piping system.If a there are no leaks,pressure rapidly designed to continuously monitor the leak is present that equals or exceeds builds in the system forcing the piping by indicating any leakage in the this amount,as much product escapes STP-MLD to open to the full-flow piping between the discharge of the from the system as is metered through position.In a system with no leaks, submersible pump and the solenoid the STP-MLD.Under this condition, it takes approximately three seconds valve in a service station dispenser. pressure cannot build up in the piping for a complete test.No further line When the submerged pump is system.When a nozzle is opened,a testing takes place until the line turned on after the system pressure poppet in the STP-MLD moves to a pressure drops significantly below the has dropped significantly below the position that restricts the flow to 2 normal static system pressure. rs �I�Ilie 1. The Tripped or Bottom 2. Leak Sensing Position 3. Non-Leak or Full Flow Position In this position the system pressure Position When the system is less than 1 psi,the has increased to approximately 18 psi This position allows full flow.The piston and poppet are in the and all the flow must travel around poppet will remain in approximately "bottom"or"tripped"position.In this the metering pin which limits it to this position as long as the system position of the poppet,product flows approximately a 3 GPH rate(at 10 psi). pressure remains at about the through the horizontal hole in the pop- If there is a leak in the system which pumping pressure.If the pressure in pet and around the metering pin at a will allow leakage to exceed this amount, the system drops when the pump is rate of approximately 2 GPM the line pressure will not build beyond turned off,either due to thermal flow into the deli¢ery,line when the this point and the valve will remain in contraction of the product or due to a submersible pump is running.In the leak sensing position with the main leak,the piston moves downward and normal operations the piping remains flow blocked.If there is an attempt to the poppet engages and seals inside full of fluid and when the submersible dispense while the valve is in this posi- the cage at about 5 psi,or approxi- pump is turned on,with a flow rate of tion,the line pressure will drop to less mately 15 feet of head,in gasoline. 2 GPM through the poppet,pressure than 1 psi,the piston will respond,and Any time the pump is turned on after builds rapidly and the poppet moves to the poppet will return to Position 1 the seal on the poppet is inside the the leak sensing position. where 2 GPM will flow to the dispensers, cage,a line test will be performed. Leaks smaller than 3 GPH will be indi- cated by the STP-MLD taking longer than three seconds to open completely because some of the flow leaks out of the system and the rest builds pressure. V If there is no leakage in the system, aCEFEWM- Z l the small flow around the metering pin FE Petro,Inc. a 4423 Triangle St. J increases the line pressure and in P.O.Box 139 . McFarland,WI 53558 approximately three seconds the piston (608)838-8786 • Fax:(608)838-6433 will move the poppet to Position 3.