Supply Of Medical Gases
Tutor:
Dr. Syed Sajjad Naqvi
Prepared By:
Dr. Umar J. Alvi
Dr. Syed Ghufran Arshad.
1
Introduction

Supply of Medical Gases:

From:



Cylinders (Manifold)
PIPED gas system
Medical gases commonly used:




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Oxygen
Nitrous oxide
Air
Nitrogen
Carbon Dioxide
2
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
Approx
dimension(mm)
490 x
102
Approx Weight
Empty (kg)
E
F
G
J
760 x 173 830 x
102
890 x 140
1290 x
178
1600 x
230
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.
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)
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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
8

Labelling
9
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Labelling




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Normal cylinder contents (Liters)
Maximum cylinder pressure (Bars)
Shelf life and expiry date
Directions for Use
Storage and handling precautions
11
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
12
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.
15

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

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
Air
Grey
Grey
5000
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.
22
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




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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
26
Safety features



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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



Cylinder Manifold
Liquid oxygen storage tank
Oxygen concentrator
28
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


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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 -160°C to - 180°C as the critical temperature
of oxygen is - 118°C).
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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.
37
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.
38
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.
40
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
41
Thank You
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