Anaesthesia gas cylinders & pipeline gas supply


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A brief discussion of anaesthesia cylinders and the medical gas pipeline system

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Anaesthesia gas cylinders & pipeline gas supply

  2. 2. Mr CylinderI am a supply tank containing high pressure gas orgas mixture @ a pressure that can be in excess of2000psig
  3. 3. We should know how we measure pressurePsi = pounds per square inchPsig = pounds per square inch gaugeDifference between measured pressure and surrounding atmpressurePsia = pounds per square inch absoluteBased on a reference point of ‘0’ pressure=perfect vacuumPsia = psig + local atm pressure
  4. 4. What does the cylinder contain?[1]nonliquefied compressed doesnt liquify @ordinary temp & pressures <2500psig E.g. O2,N2,air,Helium[2]liquefied compressed gas becomes liquid inordinary temp & pressures from 25-2500psig E.g. nitrous oxide,CO2
  5. 5. Also note that…100 kPa=1000mbar=760mm of Hg=1030cm ofH2O=14.7psi=1atmosphere
  6. 6. What is Critical Temperature?It is the temperature above which a gas cant beliquified, no matter how much pressure is applied;O2--119 C [so it is a gas in room temp]N2O36.5 C [so it is a gas+liquid mixture@roomtemp;if temp >36.5,then it exist only as gas]
  7. 7. SIZES
  8. 8. Parts of a cylinder
  9. 9. PartsBODY-VALVE-PRESSURE RELIEF DEVICEBODY--Made of steel-molybdenum alloyMRI compatible:aluminiumVALVE—bronze/brassHANDLE WHEEL—turned counter clockwise toopen
  10. 10. Valve-Port /Stem/SeatPoint of exit of gasTake careIm not the conical depression and I dont like theretaining screw.Stem closes the valve by sealing against the seat
  11. 11. Packed ValveStem sealed by TeflonTurning the stem causes the seat to turnSo called Direct actingWithstand high pressuresOpened by 2-3 full turnes
  12. 12. Diaphragm valveStem is separated from seatTurning the stem moves a metal diaphragm againstthe opposing force of a spring acting on seatCan be opened by 1/2 to 3/4 turnsLess likely to leak
  13. 13. Pressure Relief DeviceVent the contents into atmosphere if pressureinside increases to dangerous levelRUPTURE DISC: when pressure increases abovea specific level due to high temperature oroverfilling ;it rupturesrelease contentsFUSIBLE PLUG:when temperature increasesabove ‘Yield temperature’ it melts
  14. 14. Pressure Relief ValveDont confuse with othersI am a reclosing device and prevent discharge ofcontents after normal pressures have been restoredMore susceptible to leakage
  15. 15. Conical DepressionSituated above the safety relief deviceReceives retaining screw of the yolk
  16. 16. PIN INDEX SAFETY SYSTEMUsed on cylinders AEHoles on the valve positioned in an arc below theoutlet portPins on the yoke or regulator are positione to fitthese holesIf both are not aligned, port wont seat
  18. 18. PRECAUTIONSMust be tested at least every 5 yearsPressure in a filled cylinder @ 70⁰F cylinder maynot exceed the service pressure marked on thecylinder [O2,He,He-O2,CO2-O2 are allowedadditional 10%]
  19. 19. COLOUR CODINGL Oxygen White shoulder/Black body Nitrous oxide Light blue Medical air Black and white Suction Yellow Nitrogen Black Carbon dioxide Grey Helium Brown
  20. 20. MARKINGSDOT/TC specification numberService pressure in psiSerial numberIdentifying symbol of the purchaser,user ormanufacturerInitial qualifying test dateRetest date5 pointed star after last test date=may be retested every10 instead of 5 years‘+’ after test date = cylinder can be charged upto 10%in excess
  21. 21. LABELINGL
  22. 22. Tags
  23. 23. RULES FOR SAFE USE OF CYLINDERSHandled only by trained staffKeep away oils,rubber and other combustiblesubstancesNever expose to >52⁰Ckeep all connections tightTake care to avoid obstructions to discharge ports
  24. 24. RULES FOR SAFE USE OF CYLINDERSNever interchange parts of cylinder used for onegas with otherNo adapters please…Keep the valve closed when not in useValve is most prone for damageNo alterationsDont use as a rollerAvoid electric contact
  25. 25. RULES FOR SAFE USE OF CYLINDERSDont drag me..Take precautions to prevent fallingRemove wrappings before taking into OTStorage:cool,clean room with adequate ventilationSecure,safe place. Protect against all extremethings!
  27. 27. RULES FOR SAFE USE OF CYLINDERSSmall cylinders best stored uprightDont drape with any material during storageShould be grouped by contents or sizesGood segregation between empty and fullFlammable gases should not be stored in anenclosure containing oxidizing gases
  28. 28. RULES FOR SAFE USE OF CYLINDERSIdentify contents by label; Check for DOTImmediately before fitting, remove the protectivecoverPressure reducing regulators always used; inspectthem for any damage before connectingRemove dust and foreign bodies
  29. 29. RULES FOR SAFE USE OF CYLINDERSCRACKING—reduces possibility of flash fireA sealing washer in good condition should be usedValve should be opened before bringing theapparatus to the patient. Flow control valve shouldbe closed before the cylinder valve is openedWhile opening, stand to the side; not in front orbackQuick opening can generate heatflame
  30. 30. RULES FOR SAFE USE OF CYLINDERSAfter opening the cylinder, check the pressureHissing sound= leak tightenstill leak replacewasher. Localize leak with soap water.If leak in valve itself,tighten the packing nut byturning it in a clockwise directionEven if no hissing sound, check for loss ofpressure when no gas is being usedValve should be fully open when in use
  31. 31. RULES FOR SAFE USE OF CYLINDERSAn empty or near empty cylinder shouldnt be lefton anaesthesia machineValve should be closed before removing from aregulator or yokeLower part of the tag removed when cylinder isemptyCaps replaced before shipment
  32. 32. HAZARDSIncorrect cylinder,contentsIncorrect valveIncorrect color,labellingInoperable valve, damaged valveSuffocation,fires,explosion,thermal injuryContamination of contentsOverfilling, theft of Nitrous oxide cylinders
  33. 33. MEDICAL GAS PIPELINE SYSTEMSCentral supplyPipings extending to target locationsTerminal units
  34. 34. RULES FOR SAFE USE OF CYLINDERSThe maximum amount of oxygen that can bestored inside a health care facility is 20000 cubic ft
  35. 35. Design2 banks of cylindersEach have its on pressure reducing regulatorMust contain a min of two cylindersConnected to a common manifold[header]Check valve in between each cylinder lead &header
  36. 36. DesignN
  37. 37. PRIMARY/SECONDARY SUPPLYPrimary supply [duty/running] actually is theportion supplying the systemSecondary supply automatically becomes theprimary, when the latter fails [switch over done bymanifold change over device]Operating supply is the portion which normallysupplies the piping system [ consists either aprimary OR primary+secondary supply ]
  38. 38. Reserve SupplyFor larger systemsWhen operating supply fails /emergencies/maintenanceActivating switch is there for activating reservesupply
  39. 39. PressuresGases other than Nitrogen @50-55 psigNitrogen @160 psig
  40. 40. OxygenStored as liquid @ low pressures & < --148⁰C[whenlarge amounts are required] ORas compressed gas in G or H cylinders
  41. 41. Nitrous oxideBe careful against leaks; its an asphyxiantRegulator can become cold and can freezetheft
  42. 42. Medical AirAir that has no detectable liquidhydrocarbons, less than 25 ppm gaseoushydrocarbons,less than 5 mg/m3 of particulates of1 micron size or greater @ normal atmosphericpressure and a dew point @ 50 psig of less than4⁰CLow levels of nitric oxide found in ambient air mayimprove oxygenation in ventilated patients
  43. 43. PIPED AIR SYSTEMEmploy 2 or more compressors
  44. 44. INTAKEIntake location should be free of dirt/fumesQuality checked periodicallyWater content reduced with after cooler/dryerMonitored for carbon monoxideN.B. Other gases: CO2, Nitrogen
  45. 45. PIPED DISTRIBUTION SYSTEMMAIN LINES: pipes connecting the source torisers or branch lines or bothRISERS: vertical pipes connecting the main linewith branch lines on various levels of the facilityBRANCH LINES: they service a room or groupof rooms on the same level of the facilityFlexible hoses used only in exposed areas..Why?
  46. 46. PIPED DISTRIBUTION SYSTEMPressure relief valves set @50% above the normalline pressure. Close automatically when excesspressure relievedShut off valves isolate areas of the system in theevent of a problem and allows for repair.[1]Manual @ accessible areas installed in boxes[2]Service: only for authorized personnelEmergency Oxygen Supply Connector: T fittingfor connecting auxiliary source of O2
  47. 47. PIPED DISTRIBUTION SYSTEMMaster Alarm System: monitor the pressure in themain lineWhen switch over from primary to secondarysupplyWhen reserve supply is reduced to a certain levelWhen reserve is below that is required to functionWhen pressure in main line increase or decreaseArea Alarm Systems: e.g. PACU,ICUs
  48. 48. TERMINAL UNITSBASE BLOCKPRIMARY VALVE: open when male probeconnected & close when detachedSECONDARY VALVE: shut off flow whenprimary valve is removedGAS SPECIFIC CONNECTION POINT /SOCKET ASSEMBLY
  49. 49. TERMINAL UNITSGAS SPECIFIC CONNECTION POINT /SOCKET ASSEMBLYConnecter may be DISS/ Quick ConnectorEquipped with a backflow check valveQuick Connector easy to use; but leak more
  50. 50. TERMINAL UNITS-typesWall outletsCeiling mounted hosesCeiling mounted pendantsCeiling mounted columns
  51. 51. HOSESconnect anaesthesia machine to terminal unitseach have a permanaent non interchangableconnectorInlet & outlet connectorsBraid adds to strength
  52. 52. TESTING OF MEDICAL GAS DISTRIBUTION SYSTEM -INITIALblow downInitial pressure testingStanding pressure testPiping purge testTest for cross connections
  53. 53. TESTING OF MEDICAL GAS DISTRIBUTION SYSTEM-SYSTEM VERIFICATIONCross connection testTest of valuesOutlet flow testAlarm testingPiping purge testPiping purity testFinal Tie-in testOperational pressure testMedical gas concentration/air purity testSource equipment verification
  54. 54. ProblemsInadequate pressureLeaksExcessive pressuresAlarm problemsCross connection of gasesContamination of gasesFiresDepletionTheft
  55. 55. THANK YOU
  56. 56. .• .