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Schematics and Valves

Schematics and Valves. Reference info. Fundamentals -- Monoprop Blowdown System. Fundamentals -- Regulated Monoprop System. Typical Prop System Safety Features (CONTOUR). Add a Valve. Usually solenoid valves (sometimes torque motor valves may be used) Most often series dual seat

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Schematics and Valves

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  1. Schematics and Valves Reference info

  2. Fundamentals -- Monoprop Blowdown System

  3. Fundamentals -- Regulated Monoprop System

  4. Typical Prop System Safety Features (CONTOUR)

  5. Add a Valve • Usually solenoid valves (sometimes torque motor valves may be used) • Most often series dual seat • Seats may be metal or elastomer • May be sliding fit or S-spring type • Ti is available, but CRES (corrosion resistant steel) is most common • Most valves have small integral inlet filters • Consume 10 to 45 watts continuously when open • Valve to thruster seal is usually a qualified O-ring face or gland seal • Trapped volume from valve seat to thruster inlet is the “dribble volume” that exhausts after valve is closed

  6. Typical Solenoid Valve Cross-Section

  7. Valve Sources http://www.moog.com/Space/SpacecraftFluid/ http://www.valvetech.net/products.html http://www.vacco.com/space2.html

  8. Add Propellant Lines • Propellant lines may be CRES or Ti. Bipropellant systems are usually Ti because oxidizer leaches iron out of CRES. • Standard seamless tubing in several wall thicknesses is available • Fittings are rarely used, most systems are welded with orbital arc welding • I design layouts clearance must be left for weld head • Tubing diameter is sized to minimize system pressure drop quarter-inch and 3/8 inch are common outer diameters • In a system layout, provisions must be made to support tubing

  9. Group an Isolated Manifold • Thrusters may be chosen for a manifold group by function, for redundancy or by location • Isolation valves are often latch valves, but can also be pyro valves • Valve material usually is selected to be the same as tubing material • Pyro valves generate particulates and must have downstream filters • Latch valves usually have integral inlet filters • Latch valves are $$$$ • Manifolds generate coupled pressure effects

  10. Latch Valve Cross Section

  11. Typical Pyrovalve

  12. Isolation Valve Sources http://www.moog.com/Space/SpacecraftFluid/ http://www.vacco.com/space2.html http:www.conaxfl.com

  13. Add Service Connections • Service valves allow filling the propellant tank, evacuating and bleeding-in the system and adding pressurant • Usually simple, light-weight, quarter-turn shut off valves to connect to fueling system • Usually are flown with caps in place • Service inlets in system may be gravity determined low points or highpoints • Service valves are usually on the outside of the vehicle

  14. SV1 SV2 KEY GN GN 2 2 TANK 2 TANK 1 Filter N H N H 2 4 2 4 Cross-Over Latch Valve Service Valve F1 F2 SV3 SV4 Latching O2 O1 L Valve P L P LV3 Solenoid P1 P2 S Valve “Main” Latch Valves LV1 L L LV2 Pressure P Transducer S S S S S S Orifice S S S S S S S S S S Cryo Joint S S S S S S S S A1 B1 A4 B4 B2 C2 C1 C4 A3 B3 C3 A2 STEREO Schematic MR-111C 1.0 lbf Rocket Engine Assemblies

  15. O> O> O> O> Add a Pressurization System • Pressurant tank (He or N2) is usually very high pressure (3000 to 5000 psia) • Often a composite over-wrapped tank is used • Regulators are $$$$$ • Regulators are sensitive to contamination • Regulators are often less reliable than other components • Check valves are usually employed on the pressurization inlet as well as the propellant outlet of the tank for the same reason

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