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energysafe issue 39
exclusion zone error
by Michael Weber, Technical
All vent terminals must be positioned so
that expelled gases can freely dissipate
and not create a hazard.
In the context of this article a vent terminal
means the vent opening of a regulator or similar
device (having a diaphragm) or the terminal of
a vent line and around which there is an
No ignition source or opening into a
building is allowed within the exclusion zone
of the vent terminal.
Australian and New Zealand Standard
AS/NZS 5601.1:2013 clause 184.108.40.206 Vent
terminal location describes how the exclusion
zone is defined. Recently an editorial error was
identified. This error is of great concern because
it vastly distorts the size of the exclusion zone
around the vent’s discharge point.
Currently the Standard states:
AS/NZS 5601.1:2013 clause 220.127.116.11
Vent terminal location:
A vent terminal shall be located where
gas discharge will dissipate without entering
buildings or creating any hazard. The point of
(c) n cases where there is any object
(e.g. wall, ground, etc.) in the direction of
discharge and within the exclusion zone of
Figure 5.3 be located so there is no ignition
source or opening into a building within a
sphere of radius r (of Figure 5.3) centred
on the vent terminal discharge point.
T= Vent terminal diameter (mm)/50, in metres.
The exclusion zone shown below (shaded
area) depicts a space consisting of a cylinder in
the discharge direction and a hemisphere in the
opposite direction of discharge from the vent
terminal discharge point.
The error was identified above as reading
“a sphere of radius r centred on the vent
terminal discharge point” instead of “a clearance
of at least distance L centred on the vent
terminal discharge point”.
If the exclusion zone is incorrect, then there
is opportunity for vented gases to enter a building
through an opening or create a hazard in the
immediate area; this makes the positioning of
the gas discharge point crucial to ensure that
gases can dissipate safely.
Normally, where there is no obstruction in the
direction of the discharge, determining the size of
the exclusion zone is quite straight forward and the
exclusion zone is in the shape of the cylinder, length
L and diameter D, as depicted in Figure 5.3 (below).
In cases where there is an obstruction (e.g.
wall, ground, etc.) in the direction of discharge
and within the exclusion zone then the point of
discharge is to be positioned such that there is
a clearance of at least distance L to any ignition
source or opening in all directions measured
from the discharge point.
To remedy this situation ESV will be issuing a
gas information sheet alerting gasfitters to this error
and Standards Australia will publish an amendment
to AS/NZS 5601.
AS/NZS 5601.1:2013 Fig 5.3 and clause
18.104.22.168—Reproduced with permission from
SAI Global Ltd under Licence 1503-c135.
Figure 5.3: Vent terminal exclusion zone
Vent terminal diameter
Exclusion zone, m
Not exceeding 50mm
New Exceeding 50mm
for gas use
By Michelle Robertson,
Senior Media and
ESV has updated its long-standing
Code of Practice for the safe use of
LP Gas at public events in Victoria
to facilitate the safe use of LP Gas
at public events such as festivals,
fetes, markets and sporting activities.
The Code of Practice was produced
in conjunction with WorkSafe Victoria,
fire services CFA and MFB, Gas
Energy Australia and the AGA. Prior
to publication the document was also
reviewed by a number of organisations
involved in public events.
Organisers of public events have a
duty of care to provide a safe operational
environment for event staff and members
of the public. The Code is designed to
ensure an acceptable level of gas safety
to minimise gas-related incidents.
Key topics include:
»» gas appliance requirements
including approval badges and
»» cylinders and components
»» indoor, outdoor and temporary
structures for housing gas appliances
»» mobile catering vehicles and
»» documentation and notification
»» emergency planning
»» gas cylinder storage limits
»» regulations for storing and handling
The booklet also includes an
example of a Gas Safety Checklist
that catering vendors and operators
can use to check that key safety
requirements have been met.
The Code will be of use to event
organisers, appliance hirers, catering
vendors, gas suppliers, safety auditors
and others involved in the provision and
management of public events.
The document is available in printed
and digital form and copies may be
requested by emailing ESV.
lick here to request a copy of
the document in either digital
or printed form