Supply Of Medical Gases

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Supply Of Medical Gases

• Tutor
• Dr. Syed Sajjad Naqvi
• Prepared By
• Dr. Umar J. Alvi
• Dr. Syed Ghufran Arshad.

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Introduction

• Supply of Medical Gases
• From
• Cylinders (Manifold)
• PIPED gas system
• Medical gases commonly used
• Oxygen
• Nitrous oxide
• Air
• Nitrogen
• Carbon Dioxide

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Cylinders

• A gas cylinder or tank is a pressure vessel used
  to store gases at high pressure. Gases stored
  this way are called bottled gases.
• Components
• Made of Molybdenum steel in which gases and
  vapours are stored under pressure, e.g.13700 kPa
  for oxygen and 4400 kPa for Nitrous oxide.
• Shape colour of plastic disc around the neck of
  cylinder indicates the year of last examination.

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Medical Gas Cylinder
Cylinder Size D AF E F G J
Approx dimension(mm) 490 x 102 760 x 173 830 x 102 890 x 140 1290 x 178 1600 x 230
Approx Weight Empty (kg) 3.8 11.4 6.6 13 30.6 68.7
Valve Type Pin-Index Bullnose Pin-Index Bullnose Bullnose Pin-Index
Gaseous Litres 0.34 (340) 1.36 (1360) 0.68 (680) 1.36 (1360) 3.4 (3400) 10.6 (10600)
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Components

• They are manufactured in different sizes (A to
  J).
• Size E cylinders are used on the anaesthetic
  machine.
• Oxygen cylinders contain gas.
• Nitrous oxide cylinders contain a mixture of
  liquid and vapour. 75 liquid N2O
• Light weight for homes Transportation made of
  aluminium alloy.

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Different Sizes
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Marks Engraved on Cylinders

1. Test pressure
2. Dates of tests performed
3. Chemical Formulas of the cylinders content
4. Tare weight ( weight of Nitrous oxide cylinder
   when empty)

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Labelling

• Name, chemical symbol, pharmaceutical form,
  specification of the product and its Licence
  number.
• Hazard warnings and safety instructions.
• Cylinder size code

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• Labelling

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Labelling

• Normal cylinder contents (Liters)
• Maximum cylinder pressure (Bars)
• Shelf life and expiry date
• Directions for Use
• Storage and handling precautions

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Storage

• Purpose built, dry, well-ventilated and fire
  proof room, preferably inside and not subjected
  to extremes of heat.
• Not be stored near flammables
• Not be exposed to dampness, corrosive chemicals
  or fumes. Leads to corrosion of cylinders and
  valves

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Storage

• To avoid accidents, full cylinders should be
  stored separately from empty ones
• F, G and J size cylinders are stored upright to
  avoid damage to the valves.
• C, D and E size cylinders can be stored
  horizontally on shelves.
• Overpressurized cylinders are hazardous and
  should be reported to manufacturer.

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Safety Features

• The Gases and vapours should be free of water
  vapours when stored in cylinders.
• Water vapour freezes and blocks the exit port
  when the temperature of the cylinder decreases on
  the opening.

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Pin-Index

• The outlet valve uses the pin-index system to
  make it almost impossible to connect a cylinder
  to the wrong yoke.

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• The identifying code consists of a specific
  combination of two holes in the face of the valve
  into which connecting pins for a particular type
  of gas must fit in perfect alignment. For
  example, the index hole position for a cylinder
  of oxygen is 2-5, for nitrous oxide it is 3-5,
  and so on.

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Colour Coding

• Cylinders are colour coded to reduce accidental
  use of the wrong gas or vapour.

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Body Colour Shoulder Colour Pressure, kPa (room T)
Oxygen Black White 13700
Nitrous oxide Blue Blue 4400
Carbon dioxide Grey Grey 5000
Air Grey White/ Black quarters 13700
Entonox Blue White/ Blue quarters 13700
Oxygen/ helium Black White/ Brown quarters 13700
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Cylinders should be checked regularly while in
use to ensure that they have sufficient contents
and that leaks do not occur
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Cylinder Valves

• Introdcuction
• Cylinder Valves seal the cylinder contents.
• The chemical formula of the particular gas is
  engraved on the valve.

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Cylinder Valves

• They are mounted on the neck of cylinder.
• They act as an on/off device for the discharge of
  cylinder contents.
• A pin-index system prevents cylinder
  identification errors.

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Cylinder Valves

• A Bodock sealing washer must be placed between
  the valve and the yoke of the anaesthetic
  machine.
• A newly designed valve allows keyless manual
  turning on and off.

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Piped gas system

• Introduction
• Piped gas supply ( piped Medical Gas and Vacuum
  PMGV)
• PMGV system delivers gases from central supply
  points to different sites in a hospital at a
  pressure of about 400 kPa.

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Piped gas system

• Special outlet valves supply the various needs
  throughout the hospital.
• Oxygen, nitrous oxide, Entonox, compressed air
  and medical vacuum are commonly supplied through
  the pipeline system.

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Components

• Central supply points
• Cylinder banks.
• Liquid oxygen storage tank.
• Pipework made of special high quality copper with
  bacteriostatic properties.
• Outlets identified by gas colour coding, gas name
  and shape.
• Matching quick connect/ disconnect probes

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Piped gas supply

• Network of pipelines throughout a hospital from
  central supply
• Outlets are colour- and shape-coded
• Flexible and colour-coded pipelines runs from the
  anaesthetic machine to outlets

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Safety features

• Reserve bank of cylinders
• Low pressure alarms
• Single hose test, cross-connection
• Tug test, miss-connection
• Regular PGMV installation, repair and modification

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Sources of Gas supply

• Cylinder Manifold
• Liquid oxygen storage tank
• Oxygen concentrator

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Cylinder Manifold

• Introduction
• Manifolds are used to supply, Oxygen, Nitrous
  oxide and Entonox.

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• Manifold

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Components

• Large cylinders (e.g. Size J) are divided into 2
  groups, primary secondary.
• The 2 groups alternate in supplying the
  pipelines.
• All cylinders in each group are connected through
  non return valves to a common pipe.
• In turn connected to pipeline.

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Mechanism of action

• In either group all cylinder valves are open to
  allow simultaneously empting.
• The supply is automatically changed to the
  secondary group when the primary group is nearly
  empty.
• This changeover is achieved by a pressure
  sensitive device.
• Alarm is activated to alert staff

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Safety Features

• Manifold should be housed in a well ventilated
  room built of fire proof material away from the
  main hospital building.
• Manifold room should not be used as a general
  cylinder store.
• Empty cylinders should be immediately removed
  from the manifold room.

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Liquid Oxygen

• Vacuum-insulated evaporator.
• Components
• Thermally insulated vessel where vacuum is used
  as insulation
• Pressure regulator allows gas to enter pipelines
  maintain pressure of 400 kPa.
• Safety valve opens at 1700 kPa
• Control valve opens for excessive demand.

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Outer carbon steel shell and an inner stainless
steel shell, with a vacuum insulation in between
and kept cold (between -160C to - 180C as the
critical temperature of oxygen is - 118C).
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Oxygen Concentrator
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ENTONOX

• Compressed gas mixture of 50 oxygen 50
  nitrous oxide by volume.
• Used in casualty labour wards for analgesia.
• A two-stage pressure demand regulator is attached
  to the entonox cylinder.

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ENTONOX

• Entonox is the registered trademark of BOC
  Healthcare. Entonox, referred to as gas and air,
  is an analgesic used to ease pain during labour,
  trauma and minor surgical procedures.
• Entonox is administered by inhalation from a
  cylinder at a pressure of 137 bar (in the UK) or
  from a pipeline supply.

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ENTONOX

• Its analgesic effect is strong (equivalent to 5
  to 10 mg of morphine) and characterised by rapid
  onset and offset
• Entonox is self administered.
• Self-administration of Entonox remains safe
  because if enough is inhaled to start to induce
  anaesthesia, the patient becomes unable to hold
  the valve, and so will drop it and soon exhale
  the residual gas.
• The 50 oxygen in Entonox ensures the patient
  will have sufficient oxygen in their system for a
  short period of apnoea to be safe.

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Safety Features

• Liquefaction separation of contents should be
  prevented.
• Prolonged use of entonox should be avoided, due
  to the effect on bone marrow in critically ill
  patient.
• Adequate scavenging should be provided to protect
  hospital staff.

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Compressed Air

• Medical air is supplied in hospitals for clinical
  uses or to drive power tools.
• 400 kPa
• 700 kPa
• Can be supplied by cylinder manifolds or by
  compressor

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Thank You