REG NASA-LLIS-0014-1991 Lessons Learned - Use of Fail Safe Electrical Heaters Lack of Fluid Level Shutoff Capability for Portable Heaters Used for Heating Aqueous Solutions.pdf

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1、Lessons Learned Entry: 0014Lesson Info:a71 Lesson Number: 0014a71 Lesson Date: 1991-07-22a71 Submitting Organization: JSCa71 Submitted by: L. UnderwoodSubject: Use of Fail Safe Electrical Heaters; Lack of Fluid Level Shutoff Capability for Portable Heaters Used for Heating Aqueous Solutions Descript

2、ion of Driving Event: In Bldg. 9 at JSC, a 1000-watt quartz immersion heater was being used to heat a small amount of water for a chemical mixing operation in a precious metals shop. The heater, which was not equipped with a safety device to shut it off automatically in case of high temperature caus

3、ed by the water level falling below the level of the heater element, was inadvertently left on overnight. Once water in the polypropylene bucket had evaporated, the heaters protective quartz sheath melted, and subsequently ignited the bucket, leading to a fire with damages estimated at $350,000 to a

4、 NASA facility. A simulation conducted as part of the mishap investigation confirmed the plausibility of this scenario. The mishap investigation board recommended that all equipment with the potential for overheating or causing a fire should be incapable of overheating to an ignition temperature, an

5、d there should be adequate safeguards to disconnect power in an anomalous situation.Lesson Revised: June 17, 1997Lesson(s) Learned: Use of electrical heaters without fail safe capability can lead to fire and subsequent equipment and facility damage.Recommendation(s): 1. The mishap investigation boar

6、d recommended that all equipment with the potential for overheating or causing a fire should be intrinsically safe, and there should be adequate Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-safeguards to disconnect power in an anomalous situation.

7、2. Use only heaters with automatic shut off to prevent overheating and combustion.Evidence of Recurrence Control Effectiveness: All heaters with out automatic liquid control shut off were removed from use in the area. Ref. Investigation report 4-5-91Documents Related to Lesson: N/AMission Directorat

8、e(s): a71 Exploration Systemsa71 Space Operationsa71 Aeronautics ResearchAdditional Key Phrase(s): a71 Aircrafta71 Energetic Materials - Explosive/Propellant/Pyrotechnica71 Flight Operationsa71 Flight Equipmenta71 Hardwarea71 Launch Vehiclea71 SpacecraftAdditional Info: Approval Info: a71 Approval Date: 1993-09-27a71 Approval Name: Ron Montaguea71 Approval Organization: JSC/NS3a71 Approval Phone Number: 281-483-8576Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-