Conf ined Space Operations Training
AIRCRAFT FUEL CELL ENTRY SAFETY
Presentation Outline • I ntroduction • Hazard Assessment • Ventilation • Air Monitoring • PPE • Entry Team Roles • Communication
• Tools and Equipment • Training • Emergency Response • Entry Permit and Checklist
I.
I ntroduction: What and where are aircraf t f uel cells?
I ntroduction: Fuel Cell Structure • Usually located within wings • Complex internal architecture • Small access doors
I ntroduction: Who enters aircraf t f uel cells, and why? • Airplane manuf acturing workers, f or: – – – –
Assembling structure Sealing Coating I nstalling components
• Airplane maintenance workers, f or:
– I nspection, maintenance, and repair of above
I ntroduction: Applicability Not coveredinthispresentation: • Aircraf t using other than commercial jet f uel • Bladder or f oamed f uel cells • Assembly of new aircraf t • Entry into other spaces on airplanes • Entry not aboard airplanes • Flight saf ety issues
I I . Hazard Assessment • • • • • •
Physical Saf ety Hazards Ergonomic Hazards Jet Fuel Flammability Hazards Jet Fuel Exposure Hazards Other Atmospheric Hazards Miscellaneous Hazards
Physical Saf ety Hazards • Dif f icult Entry/ Exit • Working at Heights • Low Head Clearance • Entanglement • Moving airplane components • Moving airplanes
Ergonomic Hazards
• Awkward postures • Limited mobility • Resting on uneven surf aces • Repetitive motions • Vibration
Jet Fuel Hazards: Composition of Jet Fuel A • Mixture of middle range petroleum distillates (C9- 16) similar to kerosene • May include varying low levels of other more complex petroleum hydrocarbons • Additives: Antioxidants, metal deactivators, corrosion inhibitors, static dissipaters, thermal stabilizers, biocides, and f uel system icing inhibitors
Jet A Hazards: Flammability Combustibility Parameters
(too rich to burn) 4.7%
Upper Explosive Limit
47000 ppm
LEL: 0.6% EXPLOSIVE RANGE
UEL: 4.7% Vapor Pressure: <5 mm Hg Flash Point: 100-106 F o
0.6%
Lower Explosive Limit
6000 ppm
(too lean to burn) 0%
0 ppm
Explosive Range Concentrations for Jet Fuel Vapor in Air at Ambient Temperature and Pressure
Jet A Hazards: Short- Term Toxicity • Skin Contact: Drying and irritation • Eye Contact: Moderate irritation • I nhalation: – Respiratory irritation – Short- term central nervous system ef f ects such as headache, dizziness, nausea, impaired coordination, and f atigue – I nhalation of high concentrations of vapor or aerosol may lead to chemical pneumonitis, a lung condition similar to pneumonia
Jet A Hazards: Long- Term Toxicity • Solvent dermatitis • Other systemic ef f ects have been and still are under study: – – – – –
Nervous system ef f ects I mmune system ef f ects Respiratory system ef f ects Liver and kidney ef f ects Reproductive system ef f ects
Jet A Hazards: Exposure Limits
• No single consensus standard at this time • Options include: – ACGI H TLV f or Jet Fuels/ Kerosene = 28.6 ppm – NRC, USN, USAF f or Jet Fuel = 52 ppm – OSHA PEL f or Stoddard Solvent = 500 ppm (all are 8- hour TWA)
• Check with your local occupational saf ety and health jurisdiction f or an appropriate worker exposure limit concentration f or jet f uel
The New ACGIH TLV: Kerosene/Jet Fuels • 200 mg/m3, 8 hr TWA (~28.6 ppm) • As total hydrocarbon vapor • Skin notation • A3 Confirmed animal carcinogen • “based on the vapor inhalation studies with rodents”
Other Atmospheric Hazards: Oxygen • Oxygen Def iciency – Asphyxiation hazard – Causes: I ntroduction of inert gases, entrant’s respiration – Lower saf ety limit typically 19.5% • Oxygen Enrichment – Fire Hazard – Upper saf ety limit typically 23. 5% • I nvestigateanyvariationfromambient
Other Atmospheric Hazards: Hazardous Material Usage • Used inside: - Sealants – Solvents - Test agents – Coatings – Particulate f rom sanding, grinding, etc.
• Used outside: – Same classes of products as above – Vehicle exhaust – I ntroduced by ventilation system
Other Hazards: I gnition Sources • Airplane electrical components – I n tank
- Outside
• Electrical equipment taken inside – Lighting
- Tools and test eqpt.
• Static discharge – Tools and textiles
• Hot work
- Grounding
Other Hazards: Physical Exposures • • • •
Noise Heat and cold Radiation High or low air pressure
Other Hazards: Entrant Factors to Consider • Physical size • Claustrophobia • Certain health conditions, due to: – Dif f iculty of rescue – Potential f or chemical exposure – Ergonomic stresses
• Employees who regularly perf orm f uel cell work should receive preassignment and periodic health evaluations.
I I I . Ventilation • Supply vs Exhaust • Types of Air Movers • Selecting Air Movers • Ducts • Pre- Entry Ventilation • During- Entry Ventilation Set- Up
Ventilation: Supply vs. Exhaust Exhaust Ventilation Fuel Cell
Exhaust Air to
Exhaust Duct
Wing Opening to Air Duct Adapter
Air Mover
Passive Air Flow into Wing
Supply Ventilation
Fuel Cell
Passive Air Flow out of Wing
Wing Opening to Air Duct Adapter
Supply Duct
Supply Air from Air Mover
Push-Pull Ventilation Fuel Cell Exhaust Air to
Exhaust Duct
Wing Opening to Air Duct Adapters
Supply Duct
Air Mover
Supply Air from Air Mover
Figure 7: Types of Fuel Cell Ventilation
Ventilation: Air Mover Types Blowers and Venturis
Ventilation: Air Mover Selection Criteria • • • • • • •
Flow Rate Static Pressure Explosion Proof Power requirements Heating/ Cooling Portability Physical Size
Ventilation: Flexible Ductwork • • • • • •
Helical vs Collapsible Conductivity Flexibility Length Diameter I nspection
Ventilation: Pre- Entry vs. During- Entry • Pre- Entry
– Starts when tank is opened – Ventilates entire tank – Helps evaporate residual f uel – Dilutes f uel vapor concentration to saf e entry levels – Venturis of ten used to exhaust
• During- Entry – Focused at entrant’s location – Must dilute vapors f rom solvents or paints – Blowers of ten used to supply air or as part of push- pull system
Ventilation Conf iguration
8 - In c h D u c t
A ir B lo w e r
A ir B lo w e r
Air Blower
8-Inch Duct O p e n A cce ss D o or C lo s e d A c c e s s D o o r W o r k e r in T a n k W in g O p e n in g A d a p t e r
8 - In c h D u c t
I V. Air Monitoring • I nstrument types • I nstrument criteria • Pre- Entry vs During- Entry • Procedure • Oxygen • LEL • ppm f uel vapor • Other contaminants
Air Monitoring: I nstrument Types • Combustible Gas I ndicator (CGI ) – OK f or LEL – Use conversion f or jet f uel
• Photoionization Detector (PI D) – Accurate f or ppm – Can direct- read jet f uel
Monitoring I nstrument Criteria • • • • • • • •
Oxygen at 0.1% LEL At 1% ppm at 10 (if used) Real time Easy to read Adjustable Alarms Explosion proof Portable
• • • • • • • •
Rugged Fuel Resistant Pump and probe 8- hour battery Easily Calibrated Conversion f actors Temp and pressure Radio shielded
Monitoring: Pre- Entry vs. During- Entry • Pre- Entry
• During- Entry
– Done f rom outside – Measures O2 & f uel vapor concentration – Check representative areas as accessible – Ascertains if it is saf e to enter – Determines respiratory
– Done f rom inside or outside – Sampled at representative locations – Must measure f uel, O2, and any other hazards – Verif ies that conditions remain saf e – Frequency varies per
General Monitoring Procedure
• Check battery • Calibrate (CalCert once per year) • Check/ record/ program conversions • Set alarms as appropriate • Measure in order: O2, LEL, ppm • Measure appropriate areas
Monitoring: I nterpreting Results • Oxygen
– Consider reduced pressure ef f ects – I nvestigate any variation f rom ambient
• LEL
– Alarm at 10%
• PPM
– Alarm if Exposure Limit exceeded
• Other Contaminants
– Use appropriate conversion – Consider mixtures
V. Personal Protective Equipment • Hand Protection • Coveralls • Eye Protection • Ear Protection • Respirators
PPE: Gloves • • • • • • •
Nitrile ef f ective f or jet f uel Select specif ic f or other materials Breakthrough time Thickness Flexibility Dexterity Durability
PPE: Coveralls, etc De- puddle tank prior to entry Cotton coveralls usually worn Static- f ree Use other materials f or specif ic hazard • Heat stress • Hats and booties • • • •
PPE: Eye and Ear Protection • Saf ety Glasses with side shields f or most jobs • Chemical splash goggles or f ull f acepiece respirators f or certain jobs • Ear protection f or riveting, ventilation • Plugs pref erable to muf f s
PPE: Respirator Selection • Use organic vapor cartridge respirator • Do not exceed LEL • Half - mask vs f ull f acepiece • Air purif ying vs air supplying
PPE: Air Purif ying Respirators • OV cartridge f or f uel, solvents • OV/ P100 f or spray paint, particulates • Limited use lif e • Not f or I DLH or low O2 • Usually pref erred by entrants
PPE: Air Supplying Respirators • Highest protection f actors • Needs Grade D air source • Can provide cooling, avoid f ogging • Loose f itting hood only option f or beards
VI . Entry Team Roles • Entrant • Attendant • Detector Operator (usually the attendant)
• Authorizer team leader)
• Emergency Responder
(usually
Roles: Entrant • • • • •
Enters! Wears required PPE Employs saf e work practices Communicates with attendant Evacuates if unsaf e conditions or symptoms occur
Roles: Attendant Monitors well being of entrant Watches f or unsaf e conditions outside Prevents unauthorized entry Directs exit if unsaf e conditions or symptoms occur • Summons emergency services • Never enters the space • Usually operates the detector • • • •
Roles: Authorizer • Takes overall responsibility f or entry • Verif ies that all saf e entry requirements are met • Signs permit and checklist • Usually supervisors, leads, or other specif ically identif ied experienced employees • May also serve as attendant or detector operator
Other Roles • Detector Operator • Emergency Responder
VI I . Communication • Constant capability • I nitiated by either entrant or attendant • Types: – – – – –
Voice Other sound Visual Tactile Electronic • Hard wired • Wireless
VI I I . Tools and Equipment • • • • •
Signage Locks & Blocks Hand tools Wipers/ Brushes Waste Containers
Tools and Equipment (cont.)
• • • •
Lif ts Entry Stands Ladders Combinations
Tools and Equipment (cont.)
• Lighting • Electrical equipment • Pneumatic equipment • FOD control
Tools and Equipment (cont.) • Prohibited: – – – – – – –
smoking materials, matches, lighters f ood or drinks chewing tobacco metal buttons or belt buckles loose f itting jewelry watches, pagers portable telephones and radios (except communication radios as required)
I X. Training • • • •
Who What When How
Training: Who • • • • •
Entrants Attendants Authorizers Detector Operators Emergency Responders
Training: What • Def initions • Hazards • Signs of entrant distress • Entrant self rescue • Roles and responsibilities • Communication
• Atmospheric monitoring • Ventilation • PPE • Tools & Equipment • Emergencies • Permits and logging
Training: When • I nitial – Prior to assignment
• Ref resher – At set intervals, i.e. annual
• Remedial – When inadequate knowledge is demonstrated
Other Required Training • Hazard Communication • Respiratory Protection • Control of Hazardous Energy Sources • Hearing Conservation • Use of PPE • Fall Protection • Aircraf t Process Certif ications
X. Emergency Response • • • • • •
I n- house vs local jurisdiction Advance planning Qualif ications of responders Summoning of emergency services Emergency priorities Practice
Emergency Equipment • Self Contained Breathing Apparatus • Extrication tools • Lif e support equipment • Firef ighting equipment
XI . Entry Permit & Checklist • Purpose
– Systematic checklist – Designates roles – Provides documentation
• Appendices
– Entry log – Air monitoring data
• Posting • Retention