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WHAT IS IT?
 This is a 2 coil magnetic latching spool type solenoid valve which employs a permanent magnet to hold the moving solenoid and valve elements in the extended or retracted position after removal of electrical power. The design offers a compact, reliable and long life alternative to mechanically latched flow control and motor operated devices.
In this configuration, the latching solenoid is connected to a 3-way, 2 position spool valve designed for liquous media. All wetted ferro-magnetic surfaces are protected from corrosive agents by electroless nickel plating. All other wetted surfaces are of high quality stainless steel or compatible elastomeric materials.
While this unit is designed to operate at 1220 PSIG, valves of this type can be made to operate with system pressures as high as 8000 PSIG with only a slight increase in envelope size and weight.
Were control system redundancy is required, these units can be fitted with multiple coils. When control systems can provide reversing single polarity, the valves can be made to function with only one coil.
Latching valves can be designed as 2 position, 3-way (as this one) or 2-way, latching in both or either position and 3 position, 4-way configurations. |
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HOW DOES IT WORK?
 In a typical application, the valve is cycled by energizing coil no. 1, which moves the armature and valving element to the extended position causing the inlet port to be connected to outlet port no. 2 and blocking port no. 1. The permanent magnet holds the valve in this position allowing for the removal of the electric signal. Energizing coil no. 2 overcomes the permanent magnet holding force and shuttles the valve whereupon the same permanent magnet holds it in this new position. Again, the electrical signal to coil no. 2 can be terminated. In this position, the inlet port is connected to outlet port no. 1 and port no. 2 is blocked.
The total coil "on" time in each instance will be a small fraction of a second, thus conserving system power. Shuttle response time will be 20 ms of less.
The valve can also be configured to connect the outlet port to return while blocking the inlet port. |
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| HOW IS IT USED? |
| The choice of latching type valve will provide several advantages to the system designer: |
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-SIZE & WEIGHT Since the solenoid can be designed for intermittent rather than continuous duty, the coil and insulation system can be smaller. Coil-generated heating is eliminated, further reducing the coil size. Pulses of much higher energy for extremely short intervals will not significantly impact drive circuit design and allow for still further reduction in the coil winding and wire size.
-FAIL FIXED In some systems, it is beneficial to have the valve remain in its last position in the event of control circuit failure. The latching valve has that feature built into it. |
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The valve described on this data sheet is used in an aircraft turbine fuel control system. It can be used with any fluid limited only by the availability of compatible seal materials.
While S.B.C. is principally involved with the design and manufacture of valves, our family of latching solenoids are available separately for use with the customers fluid control equipment. |
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