REG NASA-LLIS-0120-1992 Lessons Learned - Liquid Tanker (LT) Liquid Level Indicator (LLI) Reliability Float Assembly Movement and Float Assembly Specific Gravity (SG).pdf

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1、Lessons Learned Entry: 0120Lesson Info:a71 Lesson Number: 0120a71 Lesson Date: 1992-08-12a71 Submitting Organization: KSCa71 Submitted by: Lisa L. MusgraveSubject: Liquid Tanker (LT) Liquid Level Indicator (LLI) Reliability, Float Assembly Movement, and Float Assembly Specific Gravity (SG) Descripti

2、on of Driving Event: On July 13, 1988, hydrazine was being transferred from partially filled drums into LT-44. There were seven drums for a total of 343 gallons. Adding the 134 gallons in LT-44 resulted in 477 gallons - well within the tanks 500 gallon capacity. As the hydrazine was being transferre

3、d from the last drum, a mechanic saw liquid spray from the vent hose and immediately closed the vent and fill valves. After securing the area, mechanics reported that all the flags at the top half of the LLI indicated the tanker was full. This suggested the magnetic liquid level gauges reliability i

4、s questionable due to erratic operations.Lesson(s) Learned: 1. Shocks/vibrations induced into a magnetic liquid level gauge may affect the position of individual flag indicators and lead to erroneous readings.2. Fluid contamination may cause a restriction of the float assembly movement within the ch

5、amber, leading to an inaccurate reading.3. Fluid in the LT having a SG which is less than the float assembly is weighted for, indicates a fluid level lower than actual, and may lead to a tank overfill.Recommendation(s): 1. Redesign flags to lock and remain stationary (until acted upon by external fo

6、rce) as fluid raises magnetic float to interact with each flag magnet.2. Filter all fluid loaded in LTs to eliminate particulate contamination which may collect on chamber walls.3. Install float assemblies weighted to a fluid SG of approx. 1.0 so fluid concentrations will Provided by IHSNot for Resa

7、leNo reproduction or networking permitted without license from IHS-,-,-register maximum level and avoid tank over filling.Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 Energetic Materials - Explosive/Propella

8、nt/Pyrotechnica71 Facilitiesa71 Ground Operationsa71 Ground Equipmenta71 Packaging Handling StorageAdditional Info: Approval Info: a71 Approval Date: 1994-06-02a71 Approval Name: James G. Klinea71 Approval Organization: KSC/HEIa71 Approval Phone Number: 407-867-7614Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-