Using Propane Safely e-learning reference material

Guide Book Series

Flammable Gases

Flammable Gases The dangers of fire and explosions

Propane LPG - Liquefied petroleum gas

These gases all have an associated asphyxiation hazard but also present the more important hazards of fire and explosion. These gases when mixed with air or oxygen and provided with an ignition source will burn. These gases may also be referred to as ‘fuel gases’.

LPG describes a group of hydrocarbon gases which exist as vapour under ambient conditions of temperature and pressure, but which can be liquefied by the application of moderate pressure.

Air content vol %

Gas content vol %

Propane (C 3 H 8 ) is colourless and odourless in its natural state. For safety reasons a stenching agent (a sweetish fish like smell) is added during production to aid detection by smell at very low levels.

0%

100%

Acetylene 2.2 - 85.0

Propane is stored inside the cylinder as a liquid under vapour pressure. One volume of liquid propane will produce approximately 270 volumes of vapour (gas). Propane is lighter than water and it therefore floats on top of it in a similar way to oil and petrol. For this reason propane cylinders must not be stored or used near to grids, drains and gullies. Propane gas is one and a half times heavier than air so any escape will find its way to the lowest level where it can remain and form a flammable mixture with the air.

Hydrogen 4.0 - 75.0

Propane 2.2 - 9.5

Propylene 2.0 - 10.5 The above chart shows the flammability concentration limits for an atmosphere of air. The red band shows the percentage range of fuel gas that presents a particular danger of fire or explosion. As the percentage of the fuel gas increases the risk of fire or explosion becomes greater. After the concentration has exceeded the upper value the air becomes saturated with the gas and an ignition becomes less likely. As the lower concentration limits are a very small percentage it is important that all fuel gas systems are leak tested prior to use and all working environments have sufficient ventilation. Methane 5.3 - 15.0 Butane 1.4 - 9.3 Carbon Monoxide 10.9 - 74.2

LPG is non-toxic but at very high concentrations in air the vapour is an anaesthetic and subsequently an asphxiate by diluting or decreasing the available oxygen in the air. Propane should always be stored and used in well ventilated areas.

If you discover a colleague collapsed in a working environment, raise the alarm, stop people from entering the area and implement the emergency rescue procedure.

Reference UKLPG CP24 Pt6 The use of Propane in cylinders at Commercial and Industrial Premises HSE INDG 227 Working safely with flammable substances

Reference UKLPG Technical Fundamentals

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