Two vacuum chambers were used in tandem to perform a launch depressurization test. The test article was mounted in a 10-ft (≈3 m) Vertical Vacuum Chamber (Chamber 248-10). The 25-ft (≈7.6-m) Space Simulator (Chamber 150-25) was rough-pumped and used for ullage.

Chamber 248-10 is 13 ft (≈4 m) in diameter by 37 ft (≈11.2 m) high; Chamber 150-25 is 27 ft (≈8.2 m) in diameter by 85 ft (≈26 m) high. A 21-in. (≈0.5-m) diameter vacuum line with a butterfly valve connects the two chambers. The inflatable space habitat would be mounted in Chamber 248-10. Chamber 150-25 would be pumped to approximately 44 Torr (≈5.9 kPa).

The launch depressurization profile was traced onto the paper of a strip chart recorder. A signal from a pressure transducer mounted on Chamber 248-10 was fed into the strip chart recorder. With the valve open to Chamber 150-25 and the building’s axial compressor, and eight Stokes pumps drawing vacuum on the vacuum line, the butterfly valve connecting Chamber 248-10 was manually opened. The operator of the butterfly valve adjusted the valve position so that the pressure transducer’s trace on the strip chart followed the trace of the depressurization profile.

This work was done by Patrick J. Martin and Paul L. Van Velzer of Caltech for NASA’s Jet Propulsion Laboratory. NPO-49615

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Performing Launch Depressurization Test on Large Test Articles Using Two Vacuum Chambers in Tandem

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This article first appeared in the April, 2015 issue of NASA Tech Briefs Magazine.

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