This publication covers the design, installation and maintenance of hydrogen vent systems used for equipment located at a customer site, it is not applicable to vent systems of hydrogen production sites with capacity exceeding 500 Nm3/hr of hydrogen. It applies to Hydrogen Refuelling Stations with standard supplies of hydrogen (liquid, gas bulk, gas cylinders, on-site production of less than 500 Nm3/hr of hydrogen).
The purpose of this publication is to provide recommendations and a methodology for the safe design of venting systems, the design of hydrogen vent stacks aims at preventing the following three main hazards:
- deflagration due to the delayed ignition of the explosive hydrogen/air mixture coming out of the vent stack;
- thermal radiation generated by the jet fire (the flame coming out of the vent stack); and
- deflagration to detonation transition inside the stack due to the acceleration of the combustion of the air/hydrogen mixture that can be present inside the venting system, in the presence of an ignition source. This hazard is relevant if air can enter the venting system.
The publication does not cover the design of the devices controlling the release of hydrogen, flare systems, or inerted vent systems.
The publication is intended for all those involved in the design, specification, installation and maintenance of hydrogen vent systems.