Piped gas supply
Description
Anaesthetists regularly use piped gas supply and suction in
different parts of the hospital. This session explores the
different components of the piped gas system, examines
safety procedures governing its usage, and describes how it
operates in conjunction with the anaesthetic machine.
Session introduction
Learning objectives:
• Recognize the key features and functionality
of the piped gas supply network and outlets.
• Demonstrate an awareness of the piped gas
supply safety features including how the
supply connects to the anaesthesia machine.
Introduction to piped gas
• This session explores the fundamental aspects of how
anaesthetists regularly use piped gas supply and
suction in different parts of the hospital for patient
care.
• The gases are supplied from central supply points of
hospital premises, such as cylinder main fold banks or
liquid oxygen storage tanks, which house large volumes
of gas.
• The gas is piped through special copper alloy piped
work, and out let valves control the flow of the gas
throughout the hospital, ensuring its instant availability
at the required locations.
Piped medical gas and vacuum (PMGV)
system
•
Gases are delivered from central
supply points and distributed via a
copper pipework system with brass
fittings which ends in outlets.
•
Copper is used in these piped
medical gas and vacuum (PMGV)
systems because it prevents the
degradation of the gases.
•
Copper also has bacteriostatic
properties, which it important in a
sterile environment.
•
PMGV systems are grease free, and
the size of the pipes vary depending
on the demand they supply.
•
As a safety feature, the pipes are
labelled at regular intervals to avoid
misconnection.
The piped supply outlets
The piped supply outlets are identified by:
• Gas colour coding.
• Gas name.
• Shape.
This provide a safety system that ensures a
patient can not be given an incorrect supply.
View the images to see the different colours
and shapes of the outlets.
Oxygen outlet
white
Nitrous oxide outlet
blue
air (400 KPa) outlet
black
Air (700 KPa) outlet
black
Suction outlet
yellow
Scavenging outlet
yellow/blue
Piped gas outlets
The safety of the patients
is paramount. PMGV system
outlets are designed to
accepts matching quick
connect/ disconnect probes.
They will only accept the
correct connecter – none of
the others will fit.
The outlets have Schrader
sockets with an indexing
collar specific to each gas or
gas mixture.
Anaesthetic machine
In order to improve the safety of gas
delivery, the following design features
are incorporated.
The PMGV system outlets are
connected to the anaesthetic machine
via flexible colour – coded hoses.
•
White for oxygen.
•
Blue for nitrous oxide.
•
Black for air.
•
Yellow for vacuum/suction.
•
Brown for scavenging.
The British standard states that the
end of the hose connecting to the
anaesthetic machine should be
permanently fixed using a nut and liner
union and gas specific non
interchangeable screw threads (NISTs).
Safety features
•
The single hose test is performed to
detect cross – connection. This
ensures that the correct gas is
flowing via the correct flow meter on
the anaesthetic machine.
•
A reserve bank of cylinder is available
should be primary supply fail. Usually
the switched off cylinders are
attached to the anaesthetic machine
and can be turned on very quickly in
the case of a central supply failure.
•
The tug test is performed to detect
misconnection – it confirms that each
pipe line is correctly inserted in to
the appropriate gas supply terminal.
Inadequately inserted pipes can
appear to be attached to the terminal
even when hanging vertically, but
their will be no gas flow.
Compressed medical air
• Medical air is supplied either for
medical use, such as during
anaesthesia via the anaesthetic
machine, or drive power tools,
such as orthopedic surgical tools
or tourniquet equipment.
• For clinical use, medical air is
supplied at pressure of 400 KPa,
while for power tools it supplied
at 700 KPa.
• anaesthetic machines and most
intensive care ventilator blenders
accept a 400KPa supply.
• The terminal outlet of the two
pressures are different, to
prevent misconnection.
Session key points
• Piped gas is supplied by a network of copper pipelines throughout
the hospital from central supply points.
• The outlet are named, colour coded and shaped coded to accept
matching probes that are permanently fixed.
• Single hose and tug tests are performed to test for cross connection
and misconnection respectively.
• There is a risk of fire from worn and damaged hoses.
• Gases are supplied under pressure of 400KPa. In addition, air is also
supplied under pressure of 700KPa.
• A vacuum of -53KPa(-400mmHg) is generated. A pump should be
capable of creating a negative pressure of -53KPa . A unit should
take no longer than 10 seconds to generate a vacuum (500mmHg)
with a displacement of air of 25L/min.
Session summary
Learning objectives:
• Recognize the key features and functionality
of the piped gas supply network and outlets.
• Demonstrate an awareness of the piped gas
supplied safety features including how the
supply connects to the anaesthesia machine.