The technical terms and descriptions of various malfunctions are:
Flame enters into nozzle or torch with a violent popping sound.
Flame either extinguishes or re-ignites at the nozzle.
Flame enters into nozzle or torch and continues burning inside with a hissing or whistling noise.
Flame enters into torch and travels back into supply system.
The speed of such a flashback is more than twice the speed of sound.
Gas with higher pressure flows back through the torch into the hose with a lower pressure.This creates a dangerous mixture of gases in the lower pressure hose.
Causes and remedial action
If a torch backfires on lighting, it is because:
- The regulators are not set to the correct pressure.
- A light has been applied before the flow of fuel gas is properly established.
The use of a spark lighter is recommended for lighting torches.
Always follow this procedure:
- Check that the regulators and nozzle size are suitable for the type of work.
- Set each regulator to the correct working pressure for the equipment in use.
- Keep the nozzle away from any source of ignition (pilot light, smouldering tow, etc.) until the fuel gas is flowing freely from the nozzle.
If the flame snaps out when the torch is in use, it is because:
- The regulator pressures and/or gas flows are incorrect.
- The nozzle is blocked.
- The nozzle has been held too close to the work.
- The nozzle has become overheated.
When this happens
- Completely shut both torch valves
- Check the regulator setting and cylinder pressures
- Relight in accordance with the above procedure
If the nozzle has become overheated, plunge nozzle and head into cold water keeping the oxygen valve open.