IEC 60974-8-2021 pdf free.Arc welding equipment – Part 8: Gas consoles for welding and plasma cutting systems.
Purging means typically include positive pressure of an inert gas and forced ventilation (e.g. use of a non-arcing fan). Any automatic means to purge the GAS CONSOLE enclosure of combustible gases shall be activated before other electrical devices are energized.
Where a fan or other device is used for purging, a malfunction shall be indicated and the system shall be prevented from continuing to operate.
After purging, the level of combustible gas shall not exceed the lower explosion level (LEL).
Conformity shall be checked in a draught-free environment by a) or b) below.
a) Simulate a continuous gas leak inside the enclosure equal to the maximum flow rate and pressure as specified by the manufacturer. Monitor and adjust the gas in the enclosure until saturation or stabilization occurs. Activate the purging device(s) and monitor the gas to ensure it reaches the LEL before a potential ignition source is any electrical devices are energized. Repeat for each type of combustible gas used.
b) Place a simulated arcing device inside the purged enclosure. Monitor and adjust the gas in the enclosure until saturation or stabilization occurs. Operate all purging means and initiate start-up sequence. Energize the arcing device to simulate the electronics electrical devices start-up, and operate continuously ensuring that no ignition occurs. Repeat for each type of combustible gas used.
NOrE4 A safe level of gas is 50 % of the LEL.
NOTE 2 The leak rare needs to be con&,dered porformiru these tests.
9.4.3 Safe design of GAS CONSOLE
9.4.3.1 Prevention of ignition
The GAS CONSOLE shall be designed to prevent an ignition caused by a gas leak in the enclosure.
Conformity shall be checked by completing the following test.
a) Place the energized equipment, i.e. the EXTERNAL GAS CONSOLE or the power source with
INTERNAL GAS CONSOLE, in a bag (or similar).
b) Simulate a gas leak inside the equipment to create an internal explosive atmosphere.
C) Monitor the mixture until it is halfway between the LEL and the UEL of the gas.
d) Operate the GAS CONSOLE for a period of at least 1 h, during which all components capable of causing ignition are cycled at least 100 times.
e) Verify that no ignition occurred during the operating period.IEC 60974-8 pdf download.