Foreword LPG
is a fuel gas commonly used as a convenient means of heat source for
cooking purpose. However, it also
has a much less known use of producing special effects. In
fact, LPG has many advantages over pyrotechnic materials in producing flame
effects: LPG is cheap and readily available, the size of the flame and
fireballs are controllable and repeatable with accuracy, the same set up
can be used many times when properly maintained, and the by-products are
environmentally green. The
aim of this Code is to outline the safety procedures that should be
followed in handling LPG equipment.
It is hoped that by observing these codes of practice, loss of life
and property would be prevented and minimized. This
Code was written internally within the Special Effects Licensing Section of
the Television and Entertainment Licensing Authority. Reference has been made to many
international standards, regulations and guidelines, including the United
States Code of Federal Regulations Title 49 Sections 173.34 and 178.51, the
US NFPA Code 160, and relevant Guidance Notes published by the Gas
Authority of the Hong Kong Government. Special
thanks are due to Mr Tassilo Baur, a First Class Special Effects Operator
in MAK
Lun-cheong, John Contents
1.
Scope This
Code of Practice is issued by the Entertainment Special Effects Licensing
Authority (the Authority). The
purpose of this document is to ensure that special effects operators and
other relevant persons are aware of the requirements with regard to the
safe use of liquefied petroleum gas (LPG) and associated equipment for the
production of entertainment special effects. It also provides guidance for good
practice so as to ensure that any person or any property is, as far as is
reasonably practicable, protected from any personal injury or unintentional
damage arising from the use of LPG. 2.
Regulatory Requirements 2.1
The use of LPG for and incidental to
the production of entertainment special effects is regulated under
Entertainment Special Effects Ordinance Cap. 560 (the Ordinance) and
its subsidiary legislation. 2.2 Under the Ordinance and
the Entertainment Special Effects (General) Regulation, a discharge permit
is required for the use of LPG for the production of entertainment special
effects. The discharge shall only be
conducted by a licensed special effects operator named as the
operator-in-charge in the discharge permit.
Other special effects operators and special effects assistants with
licensed scope of operation valid for such operation may only be allowed to
use LPG under the supervision of the operator-in-charge. 2.3 Conveyance of LPG is
regulated under the Gas Safety Ordinance (Cap. 51). Any person may carry in a vehicle an LPG
cylinder or cylinders with aggregate water capacity of less than 130
litres. Otherwise, a LPG cylinder
wagon permit issued by the Gas Authority is required. 2.4 Under the Gas Safety
Ordinance, the storage or placing of LPG containers in any premises or part
of any premises with aggregate water capacity of less than 130 litres is
exempted from the approval requirements.
Otherwise, it constitutes the construction of a notifiable gas
installation and the approval of the Gas Authority is required. 2.5 No person shall use any
container for the storage of LPG unless the container has been approved by
the Gas Authority for that purpose.
Temporary holding of LPG in an accumulator of an LPG mortar for
producing entertainment special effects is not regarded as “storage”. 2.6 Any process which
involves the transfer of LPG in liquid form from one container (other than
a disposable cylinder) to another container is prohibited under the Gas
Safety Ordinance unless the approval of the Gas Authority has been
obtained. 2.7 All tubings, connections,
valves, pressure gauges and regulators etc. shall conform to acceptable
standards. Manufacturers’
specifications for the products shall be submitted to the Authority for
inspection. 3. Technical Requirements
of LPG Equipment 3.1 Introduction 3.1.1 In the production of
entertainment special effects, it is often desirable to produce flame and
fireball effects through the controlled release of fuel gas. This method offers important safety
advantages over the use of other special effects materials because of its
relatively high degree of repeatability and predictability. 3.1.2 The type of fuel gas commonly
used is liquefied petroleum gas (LPG) which is readily available
commercially in steel cylinders. As
defined under the Ordinance and the Gas Safety Ordinance (Cap. 51), LPG
includes propane. 3.1.3 Flame effects are often
produced by means of “fire bars” through which LPG is released in a
controlled manner. Fireball effects
are often produced through the rapid release of LPG using equipment such as
“LPG mortars” and “can poppers”. 3.2 Fire Bars
3.2.1 A
fire bar is basically a steel or copper pipe and comes in all shapes and
lengths. A section of the pipe is
perforated with small holes or slots.
One end of the pipe is sealed and the other end is connected to a
LPG hose which is in turn attached to a LPG cylinder through a cutoff valve
with quick-release fitting. To avoid
damage to the LPG hose, a sufficient length of the fire bar should remain
intact so as to allow dissipation of heat generated from the burning gas. 3.2.2 A fire bar may be bent into
various shapes to produce different effects. It can be made into a ring
shape to form “burner ring” or connected to other assembly of different
shapes such as a “fishtail burner”.
Fire bars can be used for many different effects: in windows, doors,
in front of camera as foreground flame, or whenever a flame is needed on a
set. 3.3 LPG Mortars
3.3.1 An LPG mortar (or sometimes
known as an LPG cannon) is used to produce fireball effects through the
ignition of LPG rapidly released from its accumulator. It may operate without the use of any
pyrotechnic materials. While there
is a wide variety of designs, an LPG mortar normally consists of the
following elements: (i) an accumulator which temporarily holds LPG prior to its
release; (ii) a means of filling LPG into the accumulator and of measuring
its pressure; and (iii) a means of rapidly releasing the accumulated LPG. 3.3.2 The accumulator can be of
many different types and sizes but for reasons of economy and practicality
it is often a steel cylinder. It
must be noted that the accumulator shall only be used to hold LPG in vapour
form for immediate use and shall never be used as a device for the long
term storage or conveyance of LPG. 3.3.3 The
means of filling LPG into the accumulator is in some cases the valve
originally installed in the LPG cylinder but in most cases, it is replaced
by a pipe assembly which consists of: (i)
a quick-release fitting to allow
rapid connection and disconnection of the supply of LPG in the field; (ii)
a manually-operated valve to allow
the user to control the flow of LPG into the accumulator; (iii)
a pressure gauge to allow the user to
measure the pressure of LPG inside the accumulator and to determine the
amount of LPG and the rate at which it will be released; and (iv)
in applicable cases, a relief valve
may be included to prevent an excessively high pressure from developing
inside the accumulator. 3.3.4 The means of rapidly
releasing the accumulated LPG may also take different forms but in general
it consists of a large diameter, quick-acting valve. This valve is generally of one of the following
three types: (i) an electrically actuated, usually in the
form of a normally closed, full-port and internal pilot operated solenoid
valve; (ii) a pneumatically actuated, in the form of a
ball valve assembly with an integrated pneumatic actuator or an external
actuator assembly consisting simply of a pneumatic cylinder attached to the
handle of the ball valve; or (iii) a mechanically actuated, in the form of a
lever or similar mechanical valve (this type of valve is relatively
uncommon). 3.4 Construction of
Accumulators
3.4.1 An
accumulator of an LPG mortar shall conform to the United States Department
of Transportation (DOT) 4BA cylinder standard specified in the Code of
Federal Regulations, 3.4.2 The
DOT 4BA cylinders commonly available in 3.4.3 To
allow the necessary rapid release of the accumulated LPG, additional outlet
or outlets of larger diameter are required.
These outlets may be added to the cylinder (the accumulator) in
accordance with the following standards: (i) the regulations set forth in the Code
of Regulations, United States, Title 49, Section 178.51 (can be found at
www.epa.gov/fedrgstr on the internet, a copy of which is reproduced with
permission in Annex I); (ii) the regulations set forth in the Code of
Regulations, United States, Title 49, Section 173.34(i) governing the
repair by welding or brazing of DOT-4 series cylinders (can be found at
hazmat.dot.gov/regs on the internet, a copy of which is reproduced with
permission in Annex II); or (iii) other welding or brazing standards
accepted by the Authority. 3.4.4 In cases where the
modifications are not made by the manufacturer of the cylinder, the
additional outlets shall be installed in a process similar to that used in
manufacturing the cylinder and in compliance with clause 3.4.5 or 3.4.6. 3.4.5 For adding outlets to
cylinders of plain carbon steel with carbon over 0.25% or manganese over
1.00% or of alloy steel, the modifications must be in compliance with the
following requirements: (i) such modifications must be made by a
competent person; (ii) the welder shall have available to him
information as to the procedure, equipment and rod used during manufacture
of thecylinders and shall use a suitable method for the modifications; (iii) modifications must be made by metal arc
welding only; (iv) welds shall not be made on or near a
brazed joint to prevent the possibility of copper penetration; (v) the cylinders to be modified are free of
defects in welded joints in or on any pressure parts; (vi) the cylinders during welding must be free
of any materials that may impair the serviceability of the metal in or
adjacent to the weld; (vii) after modifications, the welds are to be
inspected visually for weld quality; and (viii) after modifications, the cylinder must be
reheat treated and leak tested at a test pressure of at least two times the
service pressure of the cylinder and show no defects. 3.4.6 For
adding outlets to cylinders of plain carbon steel with carbon 0.25% or less
and manganese 1.00% or less, the modifications must be in compliance with
the following requirements: (i) such modifications must be made by a
competent person; (ii) the welder shall have available to him
information as to the procedure, equipment, and rod used during manufacture
and shall use a suitable method for the modifications; (iii) welds shall not be made on or near a
brazed joint to prevent the possibility of copper penetration; (iv) the cylinders to be modified are free of
defects in welded joints in or on any pressure parts; (v) the cylinders during welding must be
free of any materials that may impair the serviceability of the metal in or
adjacent to the weld; (vi) after modifications, the welds are to be
inspected visually for weld quality; (vii) after modifications, the cylinder must be
reheat treated and leak tested at a test pressure of at least two times the
service pressure and show no defects; and (viii) in case the test shows leakage through the
weld, repair to the weld may be made provided that: (a) the leakage is not caused by cracking in
the weld; (b) weld defects must be removed by grinding
or chipping before repair by the metal arc process. The tungsten inert gas shielded arc
process may be used only when the repair can be made by puddling; (c) if metal arc process is used, only
electrodes of type E7015, 7016 or 7018 not larger than 3.2 mm (0.125 in)
diameter or equivalent shall be used; and (d) subsequent reheat treatment of the
cylinder after repair is not required. 3.4.7 It is often necessary to
install non-pressure attachments to the accumulator to facilitate mounting
of the accumulator itself or other components. Addition of these attachments to the top
or bottom of the accumulator may be made without reheat treatment provided
that the following requirements are met: (i) the attachments are made of steel of
low carbon content; (ii) the parts of the cylinder for installing
the attachments are of similar weldable material and have been previously
welded or brazed to the top or bottom of the accumulator and properly heat
treated; and (iii) the welding or brazing does not produce a
temperature in excess of 205º C (400º F) in any part of the top or bottom
material. 3.4.8 LPG cylinders belonging to
the Registered Gas Supply Companies approved by the Gas Authority for
containing LPG shall not be used or modified as an accumulator. 3.5 Means
of Filling LPG and Measuring the Pressure in the Accumulator 3.5.1 Threaded or other suitable
fittings as described in clause 3.4.2 may be used to form a suitable pipe
assembly. Such an assembly shall be
compatible with the LPG being used and have a pressure rating of not less
than the maximum service pressure rating of the LPG mortar. 3.6 Means of Rapidly
Releasing the Accumulated LPG 3.6.1 Valves connected to the
outlets of an accumulator as described in clauses 3.4.2 to 3.4.6 may be
used as a means of rapidly releasing the accumulated LPG provided that: (i) the valve components must be compatible
with the LPG being used; and (ii) the valve must have a pressure rating of
not less than the maximum service pressure rating of the LPG mortar. 3.7 Maximum Service Presure
Rating of LPG Mortars 3.7.1 The maximum service pressure
rating of an LPG mortar is the maximum pressure in the LPG mortar which
must not be exceeded during use. It
shall be taken as: (i) not more than one half of the maximum
pressure rating of the accumulator; or (ii) not more than the maximum pressure
rating of any components attached to the accumulator, whichever is the less. 3.7.2 Special effects operators
shall clearly mark the LPG mortar with the maximum service pressure rating. 3.7.3 All LPG mortars before being
put into service for the first time shall have been subject to the
following leakage tests to the satisfaction of the Authority: (i) in cases where the accumulator can be detached from the LPG
mortar, the accumulator has been leak tested at a test pressure of twice
the maximum service pressure rating and the whole LPG mortar has been leak
tested at a test pressure of 1.2 times of the maximum service pressure
rating; or (ii) in cases where the accumulator cannot be readily detached
from the LPG mortar, the whole LPG mortar has been leak tested at the
following test pressure:
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