Magnetically Damped Check Valve
Mechanical and Fluid Systems
Magnetically Damped Check Valve (MFS-TOPS-136)
Low-Chatter, Long-Lasting Check Valve
Overview
Passive valves are essential components in fluid systems, enabling flow control without external actuation. Among these, check valves are a widely used type of passive valve that allows fluid to flow in one direction while preventing reverse flow. They are commonly found in aerospace propulsion systems, industrial processing lines, and energy infrastructure.
A major operational issue with check valves is chatter – a rapid, repeated opening and closing oscillation of the valve when the pressure differential across it is insufficient to fully open the valve. Traditional check valves are often underdamped, making them prone to chatter, or overdamped, which can hinder responsiveness and efficiency. Neither approach fully resolves the issue across varying flow conditions.
To address this challenge, NASA’s Marshall Space Flight Center has developed the Magnetic Critically Damped Check Valve, a novel passive valve design that uses magnetic damping to eliminate chatter and improve reliability across a wide range of operating conditions.
The Technology
The oscillatory behavior can lead to seal wear, increased leakage, and the generation of foreign object debris (FOD), which is particularly problematic in high-reliability systems like spacecraft or cryogenic propulsion. The valve integrates a magnetic damping system into a conventional check valve architecture. Key components include a non-magnetic, electrically conductive poppet body (e.g., copper), a ferromagnetic sleeve (e.g., HIPERCO 50A) inside the poppet, and a set of Neodymium Iron Boron (NdFeB) magnetized rings arranged in alternating polarities around a non-magnetic valve body. A second ferromagnetic sleeve completes the magnetic circuit, concentrating magnetic flux through the poppet during motion.
When the valve operates, the poppet moves in response to pressure differentials. As it travels through the magnetic field, eddy currents are induced in the conductive poppet body. These currents generate a magnetic field that opposes the motion of the poppet, providing velocity-proportional damping based on Lenz’s Law. This passive damping mechanism prevents oscillation and chatter without relying on fluid viscosity or mechanical contact, enabling smooth, reliable valve operation across a wide range of flow conditions. The system is tuned to achieve critical damping by balancing magnetic flux, poppet mass, and spring rate.
This innovation offers significant advantages. In aerospace applications, the valve can be used in purge systems or cryogenic fluid lines to eliminate chatter, improving valve longevity and reducing FOD risk. In the oil and gas industry, it can enhance safety and reliability in high-pressure systems where valve failure could be catastrophic. Industrial processing systems benefit from reduced maintenance and improved flow stability. The valve’s passive, wear-free damping also lowers lifecycle costs and simplifies design integration, making it attractive for commercial licensing and deployment across multiple sectors. This technology is TRL 3 and is currently available for licensing.
Benefits
- Eliminates Chatter: Reduces wear and prevents foreign object debris generation
- Passive Operation: Requires no external power or active control systems
- Tunable Damping: Configurable to meet specific system performance requirements
- Longer Operational Life: Enhances reliability and reduces maintenance frequency
- No Dependency on Fluid Type: Performance is consistent across fluids, with temperature as the only variable
- Compact and Integrable: Designed to fit within existing valve architectures without major redesigns
Applications
- Aerospace: Propulsion systems, cryogenic fluid handling, purge systems
- Spaceflight: Launch vehicles, spacecraft, in-space docking and refueling
- Oil and Gas: High-pressure fluid systems, safety-critical flow control
- Industrial Processing: Cleanroom systems, chemical transport
- Defense: Missile systems, fuel delivery, and environmental control
Technology Details
Mechanical and Fluid Systems
MFS-TOPS-136
MFS-34385-1
"Development of a Magnetic, Critically-Damped Check Valve" David Eddleman, Molly Fisher, Andrew Smith, MSFC Science, Technology, And Engineering Jamboree (2023)
https://ntrs.nasa.gov/api/citations/20230009002/downloads/PosterJamboree_MagneticDampedValve_FINAL.pdf
|
Tags:
|
|
|
Related Links:
|
Similar Results
Magnetically Damped Check Valve
NASA's Magnetically Damped Check Valve invention is a damping technology for eliminating chatter in passive valves. Because valve failure in space missions can cause catastrophic failure, NASA sought to create a more reliable check valve damper. The new damper includes the attachment of a magnet to the poppet in a check valve to provide stabilizing forces that optimize flow and pressure conditions. Test results have proven that the Magnetically Damped Check Valve offers substantial benefits.
The Magnetically Damped Check Valve works over a wide range of flow dynamics and eliminated chatter under all flow conditions tested, allowing valves to operate under various flow rates and pressures without a risk of degradation or total destruction from chatter. This technology could provide a more simple and cost-effective solution for valve manufacturers and system designers than solutions currently available in the market.
Applications for the new valve include use in aerospace or industrial processes. NASA's damping technology was originally designed for check valves, but could also benefit pressure regulators, relief valves, shuttle valves, bellows sealed valves or other passive valves.
Pilot Assisted Check Valve for Low Pressure Applications
Check valves are traditionally designed as a simple poppet/spring system where the spring is designed to equal the force created from the sealing area of the valve seat multiplied by the cracking pressure. Since the valve seat diameter in these types of valves are relatively small, less than 0.5 inches diameter, a low cracking pressure required for back pressure relief devices results in a low spring preload. When sealing in the reverse direction, the typical 20 psid storage pressure of the cryogenic fluid is not enough pressure force to provide adequate sealing stress. To better control the cracking pressure and sealing force, a bellows mechanism was added to a poppet check valve (see Figure 2). The bellows serves as a reference pressure gauge; once the targeted pressure differential is reached, the bellows compresses and snaps the valve open. Prior to reaching the desired crack pressure differential, the bellows diaphragm is fully expanded, providing sufficient seal forces to prevent valve flow (including reverse flow) and undesired internal leakage. Room temperature testing of cracking pressure, full flow pressure, and flow capacity all showed improvements. The overall results of the test proved to be 10-20 times greater than conventional check valves with no internal leakage at three different pressure differentials.
Floating Piston Valve
Instead of looking to improve current valve designs, a new type of valve was conceived that not only addresses recurring failures but could operate at very high pressures and flow rates, while maintaining high reliability and longevity. The valve design is applicable for pressures ranging from 15-15,000+ psi, and incorporates a floating piston design, used for controlling a flow of a pressurized working fluid.
The balanced, floating piston valve design has a wide range of potential applications in all sizes and pressure ranges. The extremely simple design and few parts makes the design inherently reliable, simple to manufacture, and easy to maintain. The valve concept works with soft or hard metal seats, and the closing force is easily adjustable so that any closing force desired can be created. The fact that no adjustment is required in the design, ensures valve performance throughout valve life and operation.
This valve has many unique features and design advantages over conventional valve concepts:
- The largest advantage is the elimination of the valve stem and any conventional actuator, reduces physical size and cost.
- It is constructed with only 5 parts.
- It eliminates the need for many seals, which reduces failure, downtime and maintenance while increasing reliability and seat life.
- The flow path is always axially and radially symmetric, eliminating almost all of the flow induced thrust loads - even during transition from closed to open.
Variable-Aperture Reciprocating Reed (VARR) Valve
The VARR valve has been designed to provide a variable-size aperture that proportionately changes in relation to gas flow demand. When the pressure delta between two chambers is low, the effective aperture cross-sectional area is small, while at high delta pressure the effective aperture cross-sectional area is large. This variable aperture prevents overly restricted gas flow. As shown in the drawing below, gas flow through the VARR valve is not one way. Gas flow can traverse through the device in a back-and-forth reversing flow manner or be used in a single flow direction manner. The contour shapes and spacing can be set to create a linear delta pressure vs. flow rate or other pressure functions not enabled by current standard orifices. Also, the device can be tuned to operate as a flow meter over an extremely large flow range as compared to fixed-orifice meters. As a meter, the device is capable of matching or exceeding the turbine meter ratio of 150:1 without possessing the many mechanical failure modes associated with turbine bearings, blades, and friction, etc.
Low-Cost, Long-Lasting Valve Seal
NASA's technique simplifies the seat installation process by requiring less installation equipment, eliminating the need for unnecessary apparatus such as fasteners and retainers. Multiple seals can be installed simultaneously, saving both time and money.
NASA has tested the long-term performance of a solenoid actuated valve with a seat that was fitted using the new installation technique. The valve was fabricated and tested to determine high-cycle and internal leakage performance for an inductive pulsed plasma thruster (IPPT) application for in-space propulsion. The valve demonstrated the capability to throttle the gas flow rate while maintaining low leakage rates of less than
10-3 standard cubic centimeters per second (sccss) of helium (He) at the beginning of the valves lifetime. The IPPT solenoid actuated valve test successfully reached 1 million cycles with desirable leakage performance, which is beyond traditional solenoid valve applications requirements. Future design iterations can further enhance the valve's life span and performance.
The seat seal installation method is most applicable to small valve instruments that have a small orifice of 0.5 inches or less.
