Supply Of Medical Gases Tutor Dr Syed Sajjad

Supply Of Medical Gases Tutor: Dr. Syed Sajjad Naqvi Prepared By: Dr. Umar J. Alvi Dr. Syed Ghufran Arshad. 1

Introduction n Supply of Medical Gases: q From: n n n Cylinders (Manifold) PIPED gas system Medical gases commonly used: q q q Oxygen Nitrous oxide Air Nitrogen Carbon Dioxide 2

Cylinders n n 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: q q Made of Molybdenum steel in which gases and vapours are stored under pressure, e. g. 13700 k. Pa for oxygen and 4400 k. Pa for Nitrous oxide. Shape & colour of plastic disc around the neck of cylinder indicates the year of last examination. 3

Medical Gas Cylinder Size D AF 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 Gaseous Litres 0. 34 (340) 1. 36 (1360) 0. 68 (680) 1. 36 (1360) 3. 4 (3400) 10. 6 (10600) E F G J 4

Components q q q 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 N 2 O Light weight for homes & Transportation made of aluminium alloy. 5

Different Sizes 6

Marks Engraved on Cylinders 1. 2. 3. 4. Test pressure Dates of tests performed Chemical Formulas of the cylinder’s content Tare weight ( weight of Nitrous oxide cylinder when empty) 7

Labelling Name, chemical symbol, pharmaceutical form, specification of the product and its Licence number. n Hazard warnings and safety instructions. n Cylinder size code n 8

n Labelling 9

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Labelling Normal cylinder contents (Liters) n Maximum cylinder pressure (Bars) n Shelf life and expiry date n Directions for Use n Storage and handling precautions n 11

Storage n n n 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 12

Storage n n 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. 13

Safety Features n n 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. 14

Pin-Index n The outlet valve uses the pin-index system to make it almost impossible to connect a cylinder to the wrong yoke. 15

n 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. 16

Colour Coding n Cylinders are colour coded to reduce accidental use of the wrong gas or vapour. 17

Body Colour Shoulder Colour Pressure, k. Pa (room T) Oxygen Black White 13700 Nitrous oxide Blue 4400 Carbon dioxide Air Grey 5000 Grey White/ Black quarters 13700 Entonox Blue White/ Blue quarters 13700 Oxygen/ helium Black White/ Brown quarters 13700 18

Cylinders should be checked regularly while in use to ensure that they have sufficient contents and that leaks do not occur 19

Cylinder Valves n Introdcuction: q Cylinder Valves seal the cylinder contents. q The chemical formula of the particular gas is engraved on the valve. 20

Cylinder Valves They are mounted on the neck of cylinder. n They act as an on/off device for the discharge of cylinder contents. n A pin-index system prevents cylinder identification errors. n 21

Cylinder Valves A Bodock sealing washer must be placed between the valve and the yoke of the anaesthetic machine. n A newly designed valve allows keyless manual turning on and off. n 22

Piped gas system n Introduction: Piped gas supply ( piped Medical Gas and Vacuum PMGV) q PMGV system delivers gases from central supply points to different sites in a hospital at a pressure of about 400 k. Pa. q 23

Piped gas system Special outlet valves supply the various needs throughout the hospital. n Oxygen, nitrous oxide, Entonox, compressed air and medical vacuum are commonly supplied through the pipeline system. n 24

Components n Central supply points q q n n n 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 25

Piped gas supply n n n 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 26

Safety features n n n Reserve bank of cylinders Low pressure alarms Single hose test, cross-connection Tug test, miss-connection Regular PGMV installation, repair and modification 27

Sources of Gas supply n n n Cylinder Manifold Liquid oxygen storage tank Oxygen concentrator 28

Cylinder Manifold n Introduction: q Manifolds are used to supply, Oxygen, Nitrous oxide and Entonox. 29

n Manifold 30

Components n n 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. 31

Mechanism of action n n 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 32

Safety Features n n n 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. 33

Liquid Oxygen n n Vacuum-insulated evaporator. Components: q q Thermally insulated vessel where vacuum is used as insulation Pressure regulator allows gas to enter pipelines & maintain pressure of 400 k. Pa. Safety valve opens at 1700 k. Pa Control valve opens for excessive demand. 34

Outer carbon steel shell and an inner stainless steel shell, with a vacuum insulation in between and kept cold (between -160°C to - 180°C as the critical temperature of oxygen is - 118°C). 35

Oxygen Concentrator 36

ENTONOX Compressed gas mixture of 50% oxygen & 50% nitrous oxide by volume. n Used in casualty & labour wards for analgesia. n A two-stage pressure demand regulator is attached to the entonox cylinder. n 37

ENTONOX n n 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. 38

ENTONOX n n 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. 39

Safety Features n n n 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. 40

Compressed Air n Medical air is supplied in hospitals for clinical uses or to drive power tools. q q n 400 k. Pa 700 k. Pa Can be supplied by cylinder manifolds or by compressor 41

Thank You 42