REG NASA-LLIS-0247-1993 Lessons Learned - Hydrogen Detectors.pdf

1、Lessons Learned Entry: 0247Lesson Info:a71 Lesson Number: 0247a71 Lesson Date: 1993-08-09a71 Submitting Organization: LERCa71 Submitted by: S. PapellSubject: Hydrogen Detectors Description of Driving Event: During the filling of a liquid hydrogen test apparatus mounted in an AJ-2 airplane low-g test

2、 facility, an explosion occurred followed by a fire. The cause of the mishap was determined to be a leak due to a loose “AN“ fitting on a 1/2 inch vent line that was teed to the fill line of the research package. The ignition source was found to be hydrogen detectors mounted in the airplane near the

3、 test rig for safety considerations.Proof of the ignition source was determined by bench testing the detectors. The test consisted of flowing mixtures of hydrogen and air through them to determine if the flame fronts generated by the catalyst would be stopped by the flame arrestors. At a hydrogen vo

4、lume ratio of 5 percent, the detectors signaled a warning and the flame fronts were stopped by the screens. When the volume ratio was increased to 15 percent, the arrestors failed to confine the flame.Lesson(s) Learned: Hydrogen detectors that use catalyst generated flame fronts stopped by flame arr

5、estors (to signal the presence of combustible mixtures) can become the source of hydrogen fires.Recommendation(s): Check detectors at all combustible hydrogen-to-air volume ratios to assure that the flame fronts are stopped by the screen.Evidence of Recurrence Control Effectiveness: N/AProvided by I

6、HSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Documents Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 Energetic Materials - Explosive/Propellant/PyrotechnicAdditional Info: Approval Info: a71 Approval Date: 1994-06-15a71 Approval Name: Maria Havenhilla71 Approval Organization: LERC/EBASa71 Approval Phone Number: 216-977-1483Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-