Posted By Chris Packham Just for the record, gas cylinders rarely explode. For that they would need to contain oxygen, which, unless incorrectly filled, they will not do. They burst, then the gas comes out and, given the correct air:gas mixture, might explode. More normally it burns extremly quickly, giving the impression of an explosion.

Posted By Fred Pratley Dougie, A release of mechanical, chemical, or nuclear energy in a sudden and often violent manner with the generation of high temperature and usually with the release of gases. and/or A violent bursting as a result of internal pressure. ! Fred

Posted By Frank Macleod Doug, I am not sure what the legal definition is however this may help.... Explosion ________________________________________ The act of exploding; detonation; a chemical action which causes the sudden formation of a great volume of expanded gas; as, the explosion of gunpowder, of fire damp,etc. ________________________________________ A bursting with violence and loud noise, because of internal pressure; as, the explosion of a gun, a bomb, a steam boiler, etc. ________________________________________ A violent outburst of feeling, manifested by excited language, action, etc.; as, an explosion of wrath. ...or as quoted in my course notes from RRC state...if there is a gas/air mixture within the flammable limits in a confined space there is an explosion danger; a chance ignition will initiate the reaction, which will propogate throughout the mixture. The energy released will raise the temperature and so raise the pressure. At some point the pressure wil reach a value which will cause failure of the structure. Explosions occur as the sudden, uncontrolled release of a concentration of energy. The most usual kinds are: Pressure explosions (and implosions), Deflagrating explosions (rapid combustion in which excess pressure generated by the chemical reactions cannot dissipitate itself quickly enough and a destructive blast wave is generated), Detonations, Electrical, Nuclear. Regards Frank

Posted By Derek Holt Chris, My apologies I forgot to directly answer your question. Yes it would relate to unexploded ordnance. Therefore if it is known that the site may possibly be contaminated by UXO then a remediation plan should be formalised. This would usually necessitate that the site in question be subject to a UXO desk top study to firstly try and confirm the likely presence of UXO. i.e old military land etc. This may then be followed by a technical UXO site survey. If the presence of UXO is confirmed or there is a high likelyhood of such then the site will need to be searched and cleared before intrusive works commence. If you have a specific UXO problem or need further advice drop me a line.

Posted By Derek Holt Dougie, Just noticed your email address and note you are with Bactec. I assume you are with the Bactec that is in the business of landmine and UXO remediation? If so I would have thought you would know the answer to your own question? May I therefore enquire as to the reason for your post?

Posted By jom Doug, I don't think there is a definition that is universally accepted. The media thinks anything that goes "pop" in industry is an explosion. You can call it a sudden release of pressurised gas, but then you have to define "sudden". I think an important factor is the presence or not of a blast wave. The damage is a quantum step up when there is a blast wave. John.

Posted By Alex Ryding http://www.google.co.uk/...efine%3A+explosion&meta= All the definitions you could need!

Posted By garyh I note that the media nearly always calls explosions "detonations" whereas (reaching back to an explosives lecture nearly 30 yewars ago) not all explosions are detonations. From memory detonations are particularly destructive besause the shock front and flame are propagated at the same velocity?? My point is that we as professionals should make sure we use the correct terminology.