Ian Cook July 2004 1

For presentation at Form 2 course, BSS.

• Dormant Oxygen Systems • AD 348 Basic sailplane engineering sect 1.18.3 -1.18.18 MOSP

part 2

• July 2004

• Airworthiness Certification• Annual Inspector can carry out installation and sign off the MR and endorse

the Log Book

• Inspection level

• All components secure and no interference with controls. Endorse MR as inspection only. Functionality check to be carried out prior to use

• System is fully functional as listed in section of inspectors handbook and manufactures specifications

Ian Cook July 2004

Annual Inspection

• Confirm all items requiring pressure testing are not out of date and current for remainder of form 2 period

• If the period will be exceeded note it in Maintenance Release• Inspect the cylinder, cylinder mounts for cracking, corrosion,

security and general condition• Inspect plumbing for signs of corrosion, crushing and all lines and

fittings are securely attached.• Check flow meter / regulator for damage and general security• Check operation of Mask / Cannula• Check the system functions correctly as per manufacturers specs• Test all functions that it is practical to test at the current altitude.• Check placards and that weight and balance is correct.• (relocation of bottle and regulator may require weight and balance to

be recertified)• All components to be well clear of control cables and linkages

Ian Cook July 2004

SAFTEY NOTES

• BREATHING OXYGEN SAFTEY RELATING TO DECANTING

• Read this literature carefully as your and others lives depend on correct handling procedures

• Oxygen under high pressure in the presence of organic compounds can cause an explosion.

• If oil or grease contaminated fitting and threads come in contact with oxygen under high pressure there may be an explosion.

• This includes sunburn cream, skin grease, cooking oils.• All equipment must be clean and free of dust• Cleaning can be carried out using alcohol based solvents and then

allowing all components to dry thoroughly• All components must be stored in clean sealed plastic bags and in

storage cases provided.• Use only very clean tools specifically allocated to be used for

maintenance with oxygen systems.• Always bleed of pressure prior to working on components.

Ian Cook July 2004

Dormant Oxygen SystemsAD 348 Basic sailplane engineering sect 1.18.14 MOSP part 2

• O2 systems get neglected for most of the year• This creates a number of safety issues

• Cylinders• Corrosion and contamination of lines• Always plug /cap all lines and threaded fittings,

don’t tape• Leaking valves / breakdown of O rings /seals

(Hardening)• Store all gear easily removable in sealed clip lock

bags.• Take care not to damage copper or alloy HP

tubing. • Flexing of alloy or copper tube cause work

hardening/fatigue. Fatigue stressed tubing may be hard to detect till it ruptures.

• Thread type/flared fittings• Diluter and Pressure demand masks should be

serviced by a qualified person.• Use liquid filled gauges for HP.

Ian Cook July 2004

Safety Points for Servicing

• Degrease all tools

• Work in clean environment

• Draw schematic diagram of system prior to stripping.

• Label components.

• Have access to manufacturers manual.

• Use only O2 compatible sealants & thread tapes. Pure Teflon tape OK or Loctite 520.

Ian Cook July 2004

Common layout of components

Ian Cook July 2004

Refurbishing Dormant System

• If returning system to service care out all procedures as if it is a new installation.

• Carry out installation according to manufacturers manual.

• Check flow rates.

• Double check all work.

• Be conversant with the gear or have some one with you who is.

• Cleanliness is imperative.

Ian Cook July 2004

System Types and Altitude limits

System Type Max Height

Continuous Flow Regulator BOC Type Scot Mask 25,000 ft

Diluter Demand Regulator100% O2 @ max altitude A12 & A12a by Aro & Pioneer

35,000 ft

Pressure Demand Regulator100% O2 @ 35,000 ft with slight positive pressure flow. 42,000 ft

Electronic Oxygen Delivery system MOUNTAIN HIGHPulse Demand System

Operating parameters-50 C to +80 C100%RH @ + 50 CBattery life 40 – 60 hrs @ 25 CCylinder contents 120 Min @15,000 ft

Equates to two flights to 20,000ft****Dependant on rate of climb. 30,00 ft +

Ian Cook July 2004

Cylinders

• Corrosion in cylinders with pressures >350

• kPa.• Store cylinders full• Australian Safety Engineers 45 Catalano

Crt Canning Vale Ph 9456 2066.• Visual and Hydrostatic test.• Check compliance with A.S.• Effect on Weigh and Balance

• Plumbing Pressures• LOW pressure below 400psi /2750 kPa • HIGH pressure up to 3650psi /25,000 kPa

Ian Cook July 2004

AVIATION OXYGEN

• Use only Dry Aviators Breathing Oxygen

• BOC Code 430 • RAAF Spec G172. • moisture > .005 Mg/Litre

• Medical Oxygen may have higher moisture content.

Ian Cook July 2004

Cylinder clamping system

• Flight loads / Cylinder clamp system• Should be checked carefully• sect 1.9 inspectors hand book• Calculate up and down loads to

“Aerobatic category”• Side and rear loads to 4.5g• Rear mounted cylinder clamps to

restrain loads to 15g as per sec 1.9.5• 5lbs cylinder x 15g = 75 lbs?

Ian Cook July 2004

Copper Tubing

High Pressure Copper Tube AS 1571 - 1985

O D mm

Wall Thickness calculated Burst pressure Kpa

Max working Pressure Kpa

4.8 0.91 71500 23800

6 1.22 76000 25300

Ian Cook July 2004

Tubing and cleaning

• Always anneal copper tube after forming.• Heat to cherry red (1000 F) and quench in water.• Replace if in doubt.• Clean lines and fitting internally and externally

especially after annealing.• Clean by immersing in 1 pt HCl to 3 pt water for

3min and then rinse thoroughly.• Clean / degrease using sonic baths• Flushing solvents acetone, trichloroethylene or

trichlorotrifluoroethane (fluorosil).• Dry with heat @70 c for 30 min• Blow dry with filtered breathing air or nitrogen

Ian Cook July 2004

LEAK TESTING

• Check all connections after installation for leaks.

• Use soapy water or proprietary brand leak detection solution.

Ian Cook July 2004

Sealants & O RingsTeflon Hazard

• Use only O2 compatible sealants & thread tapes.

• Pure Teflon tape “Oxy Tape” from dispensers marked “Mil T27730”.

• Loctite 520 white paste which will set in the presence of oxygen.

• Some “Teflon sealants are not pure and my be combustible at High pressures”

• Only use flexible HP hoses approved for breathing oxygen.

• Use O Rings approved for oxygen.

Ian Cook July 2004

Cylinder FillingBasic sailplane engineering Sect 1.18.15.3

• AS 3848.2—1999

• Australian Standard™

• Filling of portable gas cylinders

• Part 2: Filling of portable cylinders

• for self-contained underwater

• breathing apparatus (SCUBA) and

• non-underwater self-contained

• breathing apparatus (SCBA)—

• Safe procedures

• AS 2030—1999

• Australian Standard™

• Periodic testing

Ian Cook July 2004

Summary

• Your own life or other is be dependant on the efficient and reliable operation of this equipment.

• O2 systems tend to be neglected during the season. Included inspecting the system in your D.I.

• If in doubt about some aspect of the O2 system consult a more qualified person

• I recommend using O2 on all flights over 5,000 ft. I have felt considerably more refreshed at the end of long XC flights.

• Ref Stirlings Wave Camp Manual Section 7 -9Edited by I.D.M. Robertson

AS 3848.2—1999. AS 2030—1999