Compressed
Gas
Oxidizing
Agent
Explosive
Flammable
The compressed gas
industry use colour codes
as a quick reference guide
to the cylinders contents.
This should not be used
as a definitive indicator of
the contents only as a
guide.
The only way to accurately
identify the contents of a
cylinder is the label.
Oxygen
Description
BOC oxygen is typically supplied with a purity of 99.5% or better.
Colourless and odourless.
Does not burn but supports and accelerates combustion.
Hazards
However most lubricants are not compatible; oil and grease can ignite
spontaneously burning with explosive violence and should not be used
with oxygen.
Oxygen must never be used with Polytetraflouroethylene (PTFE) tape,
as it will cause combustion.
Uses
Widely used with a fuel gas for cutting, welding, brazing and soldering.
The use of oxygen gives higher flame temperatures than if air is used.
Copper, brass and high quality stainless steel are the most commonly
used metals and are compatible with oxygen
Propane
Description
propane is heavier than air. Leakage will collect in low-lying areas such as drains or
ducts.
most propane is stenched to give a fish-like odour.
supplied as a liquid in cylinders available for vapour or liquid withdrawal from
cylinders.
non-toxic (can cause dizziness at high concentrations). highly combustible, having
explosive limits in air between 2.2% to 9.5% by volume
Hazards
propane has some solvent properties and therefore hoses should be of the correct
material as shown and the correct colour, orange.
only use purpose-manufactured equipment with propane and always use correct
lighting up procedures.
you will require a separate regulator, flashback arrestors, hoses, nozzles and torches
when using propane.
Uses
used in oxy-propane soldering and brazing
Acetylene
Description
the hottest and most efficient of all the fuel gases, providing high levels
of productivity
lighter than air and will not accumulate at low levels
low ignition energy
non-toxic (may cause dizziness in high concentrations)
acetylene is stored in specially-designed cylinders to prevent
decomposition.
It can form explosive acetylide compounds with some metals, most
notably copper, silver and mercury.
Hoses used with acetylene are coloured red and are designed to resist
acetone. For this reason other fuel gas hoses must not be used.
Hazards
care must be taken when using acetylene as it is an asphyxiant.
acetylene is highly reactive. It is dissolved in acetone and contained
within a porous mass inside the cylinder
Carbon Dioxide
Description
A colourless and odourless gas that can cause the nose to sting in high
concentrations. Toxic in high concentrations. An asphyxiant (does not support
life).
Slightly corrosive in the presence of moisture.
Heavier than air, carbon dioxide will collect in ducts, drains and low-lying areas.
At elevated temperatures, carbon dioxide reacts with many substances.
Cylinders of both liquid and gaseous carbon dioxide are available. Dip tubes
are used in liquid withdrawal carbon dioxide cylinders to extract the liquid from
the cylinder. The tube runs down the centre of the pressurised cylinder and
draws the liquid up through the valve. To identify these cylinders, a white stripe
is painted down the length of the cylinder.
Benefits
Higher density than air provides good blanketing properties.
Applications and Uses
Balancing pH levels in swimming pools
Compressed liquid carbon dioxide can also be used in small pipe-freezing
applications
Hydrogen
Description
Odourless, colourless and tasteless
Will ignite easily so cylinders must not be snifted
Burns with an invisible flame
Produces a flame of approximately 2834°C when used with
oxygen
Benefits
Has the highest thermal conductivity of all gases.
Is supplied at higher pressures than other fuel gases.
Burns with a clean carbon-free and soot-free flame.
Applications and Uses
Can be used as an alternative power source when used
with a fuel cell to generate electricity.
In the glass industry, used to form the rim on glasses
Fuel Gasses
• Fuel gasses are burned to generate heat,
different gasses have different
characteristics; you should familiarize
yourself with the fuel gas that you are
using.
• Make sure the equipment that you are
using is suitable for the gas that you are
using.
Nozzle
Gas nozzles come in a variety of sizes depending on the application. All of
the nozzles burn at the same temperature but the bigger the nozzle the
greater the volume of heat that can be delivered.
Too small a nozzle will not get the work up to soldering temperature.
Too big a nozzle will heat the work up too quickly and risk over heating or
burning the pipe & fitting.
Torch Body
Most manufactures make proprietary
nozzles that only fit there own product,
you will need to know the manufacturer
and model number when ordering
replacement nozzles.
Some torches have a built in igniter
powered via a peizo electric unit.
The torch should be visually inspected
prior to use making sure there are no
signs of damage, the nozzle and hose
are securely attached and the controls
function correctly.
Hose
Propane hose should be orange, this is the
standard colour for propane. Propane hose
must not be used for acetylene.
The hose should conform British Standard
BS5120 or the new European Standard
EN559.
The hose is usually fitted to the regulator and
torch by the manufacturer; the hose can be
bought in lengths and fitted by the end user.
When fitting a hose you must use the correct
fittings / clips and it must be test for both
mechanical strength and gas soundness.
Regulator
The regulator as the name suggests regulates
the amount of gas that passes from the cylinder
to the torch.
The regulators are designed specifically for the
gas so you must only use the specified regulator
for each type of gas.
Some regulators are fixed giving you a constant
line pressure, others are adjustable allowing you
to vary the amount / flow of gas.
Except for a very small number of specialist
applications fuel regulators have a left hand
threat so they can not be fitted incorrectly.
Torch On/Off Valve
The on / off valve not only turns
the gas on & off but also controls
the gas flow through the torch,
this makes the flame bigger or
smaller.
Make sure the valve works with a
smooth operation and that it can
be turned off quickly if there is a
need.
If the knob is damaged or missing
do not try to operate the
equipment.
Cylinder Isolation Valve
The cylinder isolation valve allows the gas out
of the cylinder into the regulator.
There are two main types of isolation valve;
wheel operated and key operated.
The wheel operated valve pictured above left is
opened and closed by hand.
The key operated isolation valve requires a
special ‘key’ to open and close the valve.
Make sure you familiarize yourself with the
operation of the valve before you use the
equipment, in case you need to turn the
equipment off in a hurry.
Left-handed Nut
Fuel gasses have a left hand thread, this is a
safety feature and stops them being
connected to the wrong part of the heating or
cutting equipment.
The left handed thread is denoted by the
‘notch’ machined in the nut.
The bottom picture shows the ‘bullnose’ this
is the part of the regulator that creates the
gas tight seal. The bullnose should be
protected from damage as small scratches
can lead to gas leaks.
Hose Crimp Clip
When fitting hoses the correct clip must be used.
The clip pictured above left is often referred to as
a ‘jubilee clip’ these should not be used on gas
hoses as the clip can be over tightened and cut in
to the hose.
The clip pictured below left is the type of clip that
should be used be used. These are called double
eared hose clips and are fitted with a special
crimping tool.
Use of Blowtorch
• As with any task planning is an important
part of the safe operation.
• Look at where you are about to work and
situate your gas cylinder in an appropriate
place; close enough to be able to access if
needed but far enough away that it will not
be heated be the torch. It should also be
out of you way so it does not constitute a
trip hazard.
Purging
• The hose should be purged of air prior to
lighting.
• Purging is the process of opening the
control knob on the torch for a few
seconds to push any air out of the hose.
This dramatically reduces the risk of
flashback.
Lighting
• When lighting the blowtorch you should use a
spark igniter as lighters can explode if the
torch is passed over them.
• The gas is turned on and then ignited, the
flame is adjusted to the required setting.
• Once the work is complete the gas is turned
off and the flame extinguished.
• Take care where you place the torch down as
the nozzle will be very hot for some time.
Leaks
• If you can smell gas even when the torch
is off check the tightness of the regulator, if
it is lose tighten the nut by ¼ of a turn.
• If the hose is damaged it should be
replaced.
• If there are flames coming out where the
nozzle is attached to the body of the torch
check to see if the nozzle is fitted correctly.
Planning
• Always plan for unexpected eventualities,
have a plan of what you are going to do if
there is a fire, a gas leak, etc.
• Have fire fighting equipment available and
accessible.
Risks
• When using a blowtorch you can become
very focused on the task in hand and become
oblivious to your surroundings, as a result
you can accidently set fire to the surrounding
area; to minimize this risk make sure all
flammable material is removed from the area
you are working in.
• Remember heat can travel through heat
resistant mats and scorch any surface
behind.
Questions