In fabrication workshops the length and breadth of the UK we frequently find time-served operators who have not been trained how to correctly light oxy-fuel gas systems and who use either the wrong spark lighter or a naked flame (cigarette lighter) to light up the system.
As there are many different designs and manufacturers of oxy-fuel gas cutting and burning equipment, operators must undertake the correct light up procedure for their specific equipment as laid down in the manufacturer’s or supplier’s instruction manual.
Why Purging Is Essential Before Lighting
In a previous blog we covered flashbacks and the causes of flashbacks. Within the industry it is estimated that 90% of all flashbacks occur because operators fail to correctly purge air and/or mixed gases from the oxy-fuel system prior to lighting the torch or blowpipe.
Before attempting to light the blowpipe, operators must purge each hose separately to establish only oxygen or fuel gas in the appropriate hose, closing each blowpipe valve after the relevant hose has been purged.
This purging should be continuous, typically lasting for three to five seconds for a standard length (five metre) of hose. Longer times will be required for longer hose lengths.
It is essential that the procedure of purging gas systems takes place following each period of non-use, change of gas cylinder or disassembly of equipment.
Purging should take place in a well-ventilated space away from any sources of heat and/or ignition.
The Correct Procedure for Lighting Oxy-Fuel Gas Systems
Once the hoses have been purged the operator can then light the system. The fuel gas should always be ignited before introducing the oxygen stream.
The nozzle should be pointing upwards for lighter-than-air gases (for example, acetylene) and downwards for heavier-than-air gases (for example, propane).
Light the blowpipe and adjust it in accordance with the supplier’s instructions. It is recommended that a spark lighter is used for this purpose.
Choosing the Correct Spark Lighter
Due to its high flame speed, acetylene is easy to light and only requires a small spark. For this purpose, a pistol style lighter is required.
Due to its low flame speed, propane is rather more difficult to ignite. Consequently, a cup style lighter is required. With the nozzle facing downwards, when the propane begins to flow the gas fills up the cup. The large flint is then struck to ignite the gas.
Key Points to Remember
Please ensure that your operators are using the correct type of spark lighter and are purging the system each time they light up the torch or blowpipe.
Remember, it is essential that the procedure of purging oxy-fuel gas systems takes place following each period of non-use, change of gas cylinder or disassembly of equipment.
If your operators require awareness or practical training with oxy-fuel gas systems, please contact us on 01270 758890 or at admin@gassafeconsultants.co.uk.
