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SSME 1.

SSME INSTRUMENTATION CALIBRATION COEFFICIENTS

Consideration

During the processing flow and prelaunch it is required to perform an automated checkout and calibration of the SSME pressure sensors. To accomplish this, all helium must be vented off the SSME to perform an accurate calibration.

Impact

• Serial time to vent and reapply helium
• Causes unreliable readings of mass spectrometer due to background He in the OPF
• Venting is noisy
• Waste of helium

Design Objectives

• Allow a calibration to take place with helium applied
• Eliminate the need for a calibration by providing nominal coefficients

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Edgar Zapata, NASA Kennedy Space Center

Shuttle Process Engineering Directorate, Fluid Systems Division