Leak Test for Pressure-Sealing Zippers
Test jig checks either side of pressure-sealing zippers for leaks. Procedure takes little time, and seal failure determined before zipper incorporated into suit.
Erickson, E.↗
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Ground-Based Cryogenic Leak Test of Fittings for Cryogenic Fluid Management
Mechanically connected fluid joints are virtually unavoidable in complex cryogenic system designs. In the case of spacecraft, the performance of these joints is critical to mission success. This is especially true for long-duration space missions where even very low leak rates can eventually lead to significant propellant losses or failure of vital cryogenic cooling systems. NASA has recently undertaken an effort to quantify the leak rate of Vacuum Coupling Radiation (VCR) fittings over the temperature range from ambient to 20 K, both before and after exposure to a launch vibration profile. A test apparatus employing a cryocooler and a calibrated helium mass spectrometer was developed, validated, and used to obtain quantifiable leak rates at a fitting test pressure of 31 bar (450 psig). Three different fitting sizes were tested, 25.4 mm (¼ inch), 12.7 mm (½ inch), and 6.35 mm (1 inch) and two gasket materials, stainless steel, and silver-plated nickel. Each fitting configuration (size/seal material) was subjected to two consecutive cryogenic thermal cycles/measurement tests, followed by a launch vibration test profile at ambient temperature, and then two additional cryogenic thermal cycles/measurement tests. The design and development of the test apparatus, and test data are presented and discussed in detail.
G J Tamasy↗
Nondestructive leak testing
Method provides opportunity to effect repairs without compromising integrity of enclosed circuitry or mechanism by loss of atmosphere or by ingestion of foreign matter or gas. It is possible to detect leaks in modules which are sealed while fully evacuated, partially evacuated, or containing some form of gas.
Lusby, T. K., Jr.↗
Fixture facilitates helium leak testing of pipe welds
Fixture facilitates inspection testing of circumferential pipe welds for vacuum tightness, using helium gas as a leakage tracer in conjunction with a mass spectrometer. It consists of a split rubber torus and a mating clamping ring with a vacuum hose fitting.
Roney, J. A.↗
Quantitative leak test design guide Final report, 8 Dec. 1966 - 7 Aug. 1967
Calibrated enclosure system using helium injection method for estimating leakage rates
Hollinger, P. L.↗
Leak decay method of helium bombardment leak testing
Method for verifying hermetic seal quality of small components is described. Procedure for using helium bombardment and examination with mass spectrometer is described. Technique eliminates errors in seal quality determination and checks quality of seals without contaminating products.
Garton, W. P.↗
Double-O-Ring Plug For Leak Tests
Pressure plug features redundant O-ring bore seals and axial port opening laterally into space between O-rings to enable testing of seals. Axial passage in plug connected through radial passage to space between O-rings. Opening used to test O-rings, then sealed with smaller O-ring compressed by machine screw. Useful to seal test or cleanout holes normally kept closed in hydraulic actuators, pumps, and other pressurized systems.
Greene, James H.↗
Ground-Based Cryogenic Leak Test of Fittings for Cryogenic Fluid Management
Explore the source record for details and available documents.
Gabor Tamasy↗
Reliable method for testing gross leaks in semiconductor component packages
Simple, reliable, inexpensive method for gross-leak testing has been devised, based upon the conventional fine-leak technique. The sensitivity ranges from the detection of very large leaks down to leaks of 10 to the minus seven cc helium per sec.
Altshuler, T. L.↗
Development of Test Protocols for International Space Station Particulate Filters
Air quality control on the International Space Station (ISS) is a vital requirement for maintaining a clean environment for the crew and the hardware. This becomes a serious challenge in pressurized space compartments since no outside air ventilation is possible, and a larger particulate load is imposed on the filtration system due to lack of gravitational settling. The ISS Environmental Control and Life Support System (ECLSS) uses a filtration system that has been in use for over 14 years and has proven to meet this challenge. The heart of this system is a traditional High-Efficiency Particulate Air (HEPA) filter configured to interface with the rest of the life support elements and provide effective cabin filtration. The filter element for this system has a non-standard cross-section with a length-to-width ratio (LW) of 6.6. A filter test setup was designed and built to meet industry testing standards. A CFD analysis was performed to initially determine the optimal duct geometry and flow configuration. Both a screen and flow straighter were added to the test duct design to improve flow uniformity and face velocity profiles were subsequently measured to confirm. Flow quality and aerosol mixing assessments show that the duct flow is satisfactory for the intended leak testing. Preliminary leak testing was performed on two different ISS filters, one with known perforations and one with limited use, and results confirmed that the testing methods and photometer instrument are sensitive enough to detect and locate compromised sections of an ISS BFE.Given the engineering constraints in designing spacecraft life support systems, it is anticipated that non-industry standard filters will be required in future designs. This work is focused on developing test protocols for testing the ISS BFE filters, but the methodology is general enough to be extended to other present and future spacecraft filters. These techniques for characterizing the test duct and perform leak testing can be applied to conducting acceptance testing and inventory testing for future manned exploration programs with air revitalization filtration needs, possibly even for in-situ filter element integrity testing for extensively long-duration missions. We plan to address the unique needs for test protocols for crewed spacecraft particulate filters by preparing the initial version of a standard, to be documented as a NASA Technical Memorandum (TM).
Filtration↗
Temperature and Atomic Oxygen Effects on Helium Leak Rates of a Candidate Main Interface Seal
Helium leak tests were completed to characterize the leak rate of a 54 in. diameter composite space docking seal design in support of the National Aeronautics and Space Administration s (NASA's) Low Impact Docking System (LIDS). The evaluated seal design was a candidate for the main interface seal on the LIDS, which would be compressed between two vehicles, while docked, to prevent the escape of breathable air from the vehicles and into the vacuum of space. Leak tests completed at nominal temperatures of -30, 20, and 50 C on untreated and atomic oxygen (AO) exposed test samples were examined to determine the influence of both test temperature and AO exposure on the performance of the composite seal assembly. Results obtained for untreated seal samples showed leak rates which increased with increased test temperature. This general trend was not observed in tests of the AO exposed specimens. Initial examination of collected test data suggested that AO exposure resulted in higher helium leak rates, however, further analysis showed that the differences observed in the 20 and 50 C tests between the untreated and AO exposed samples were within the experimental error of the test method. Lack of discernable trends in the test data prevented concrete conclusions about the effects of test temperature and AO exposure on helium leak rates of the candidate seal design from being drawn. To facilitate a comparison of the current test data with results from previous leak tests using air as the test fluid, helium leak rates were converted to air leak rates using standard conversion factors for viscous and molecular flow. Flow rates calculated using the viscous flow conversion factor were significantly higher than the experimental air leakage values, whereas values calculated using the molecular flow conversion factor were significantly lower than the experimentally obtained air leak rates. The difference in these sets of converted flow rates and their deviation from the experimentally obtained air leak rate data suggest that neither conversion factor can be used alone to accurately convert helium leak rates to equivalent air leak rates for the test seals evaluated in this study; other leak phenomena, including permeation, must also be considered.
Penney, Nicholas↗
Valve, normally open, titanium: Pyronetics Model 1425
An operating test series was applied to two explosive actuated, normally open, titanium valves. There were no failures. Tests included: proof pressure and external leakage test, gross leak test, post actuation leakage test, and burst pressure test.
Avalos, E.↗
Ion pump and leak life test
The fabrication and long term testing of a flight type ion pump and sintered inlet leak are described. These tests were conducted over a period of one year at an ion pump pressure of approximately 0.000001 torr. These long term tests were conducted to investigate aging of ion pumps and leaks under continuous use. Pumping speed and leak conductance, as well as other parameters, were measured on a weekly basis with ion pump start tests conducted on a monthly basis.
Ierokomos, N.↗
Hermetic edge sealing of photovoltaic modules
The feasibility of using an electrostatic bonding (ESB) and ultrasonic welding process to produce hermetic edge seals on terrestrial solar cell modules was investigated. The fabrication sequence is to attach an aluminum foil "gasket' to the perimeter of a glass sheet. A cell circuit is next encapsulated inside the gasket, and its aluminum foil back cover is seam welded ultrasonically to the gasket. An ESB process for sealing aluminum to glass was developed in an ambient air atmosphere, which eliminates the requirement for a vacuum or pressure vessel. An ultrasonic seam welding process was also developed which did not degrade the quality of the ESB seal. Good quality welds with minimal deformation were produced. The effectiveness of the above described sealing techniques was tested by constructing 400 sq cm (8 x 8 s64 sq in) sample modules, and then subjecting them to nondestructive fine and gross leak tests. The gross leak tests identified several different causes of leaks which were then eliminated by modifying the assembly process.
Nowlan, M. J.↗
An Evaluation of Ultra-High Pressure Regulator for Robotic Lunar Landing Spacecraft
The Robotic Lunar Lander Development (RLLD) Project Office at NASA Marshall Space Flight Center (MSFC) has studied several lunar surface science mission concepts. These missions focus on spacecraft carrying multiple science instruments and power systems that will allow extended operations on the lunar surface. Initial trade studies of launch vehicle options for these mission concepts indicate that the spacecraft design will be significantly mass-constrained. To minimize mass and facilitate efficient packaging, the notional propulsion system for these landers has a baseline of an ultra-high pressure (10,000 psig) helium pressurization system that has been used on Defense missiles. The qualified regulator is capable of short duration use; however, the hardware has not been previously tested at NASA spacecraft requirements with longer duration. Hence, technical risks exist in using this missile-based propulsion component for spacecraft applications. A 10,000-psig helium pressure regulator test activity is being carried out as part of risk reduction testing for MSFC RLLD project. The goal of the test activity is to assess the feasibility of commercial off-the-shelf ultra-high pressure regulator by testing with a representative flight mission profile. Slam-start, gas blowdown, water expulsion, lock-up, and leak tests are also performed on the regulator to assess performance under various operating conditions. The preliminary test results indicated that the regulator can regulate helium to a stable outlet pressure of 740 psig within the +/- 5% tolerance band and maintain a lock-up pressure less than +5% for all tests conducted. Numerous leak tests demonstrated leakage less than 10-3 standard cubic centimeters per second (SCCS) for internal seat leakage at lock-up and less than10-5 SCCS for external leakage through the regulator ambient reference cavity. The successful tests have shown the potential for 10,000 psig helium systems in NASA spacecraft and have reduced risk associated with hardware availability and hardware ability to meet RLL mission requirements.
Burnside, Christopher↗
Fracture control plan for propellant and pressurant tanks
To assure the functional integrity of the GLL-RPM fuel and pressurized gas tank, all activities during entire lifetime of the tank, from manufacture to the end of the mission, must be monitored. Specifications are given for all procedures which influence the tank structure including design, manufacture, cleaning, test operations, and storage. Tests to be conducted to demonstrate that requirements of the fracture control plan are satisfied include static tests, cyclic load tests, proof tests, He-leak test, and acceptance tests.
Source record↗
An Evaluation of a High Pressure Regulator for NASA's Robotic Lunar Lander Spacecraft
The Robotic Lunar Lander (RLL) development project office at NASA Marshall Space Flight Center is currently studying several lunar surface science mission concepts. The focus is on spacecraft carrying multiple science instruments and power systems that will allow extended operations on the lunar surface or other air-less bodies in the solar system. Initial trade studies of launch vehicle options indicate the spacecraft will be significantly mass and volume constrained. Because of the investment by the DOD in low mass, highly volume efficient components, NASA has investigated the potential integration of some of these technologies in space science applications. A 10,000 psig helium pressure regulator test activity has been conducted as part of the overall risk reduction testing for the RLL spacecraft. The regulator was subjected to typical NASA acceptance testing to assess the regulator response to the expected RLL mission requirements. The test results show the regulator can supply helium at a stable outlet pressure of 740 psig within a +/- 5% tolerance band and maintain a lock-up pressure less than the +5% above nominal outlet pressure for all tests conducted. Numerous leak tests demonstrated leakage less than 10-3 standard cubic centimeters per second (SCCS) for the internal seat leakage at lock-up and less than 10-5 SCCS for external leakage through the regulator body. The successful test has shown the potential for 10,000 psig helium systems in NASA spacecraft and has reduced risk associated with hardware availability and hardware ability to meet RLL mission requirements.
Burnside, Christopher G.↗