Hydrogen cylinder valve

[Shayan Zariean]

Dear Readers
There are Compressed Hydrogen Cylinders manufactured based on ISO 11120 and their working pressure is 180 bar and test pressure 297 bar. The valve installed on them is equipped with rupture disc of which bursting pressure is 3360 psi. I would like to know is installing valve with rupture disc correct on hydrogen cylinders. when this rupture disc bursts the hydrogen will comes out with high pressure and is dangerous.
Thanks in advance for your help

 

[The Obturator]

I'm no expert of Industrial Gas Cylinders, but a SRV will still need to relieve the pressure. A rupture disc is used for convenience and cost. Bear in mind you have an non toxic gas. The rupture disc is probably so positioned to allow non direct flow.

Per ISO, only the term Safety Valve is used regardless of application or design.

 

[don1980]

Understand that the H2 will almost certainly ignite when/if the disk bursts, and this will continue until the cylinder is emptied. Consider whether you want to use a PRV rather than a disk. If you use the disk, then route the relief vent in such a way that it's safe (no one is at risk of being burned, and nothing is at risk of catching fire from the H2 flame). Recognize that the H2 flame will be invisible to the eye, so don't count on the flame being seen by personnel.

 

[moltenmetal]

A rupture disc is used because it's a GAS FILLED CYLINDER- in the case of a fire, you would MUCH rather have the cylinder vent its flammable contents in a controlled fashion through a rupture disc than have a PSV vent and reseal as the cylinder heats up and eventually RUPTURES because it is too hot to handle the pressure!

For gas filled vessels potentially exposed to fire, you need either a PSV AND a fusible plug or other temperature relief device, or you use a rupture disc. The benefits of reduced cost, less risk of leakage, less maintenance etc. are taken as side benefits over the avoidance of catastrophic failure during fire.

 

[georgeverghese]

The process safety section in Perry Chem Engg Handbook (7th edn) states the same caution from @don1980- hydrogen may autoignite even when the vessel is electrically grounded - min ignition energy for hydrogen is 1/10th that of hydrocarbons.
If you must live with the RD, also constrain the max operating pressure to say 80% of the RD setpoint, which in this case would be approx 185barg.

 

[Shayan Zariean]

Thanks for every body help
Overally I would like to konw using valve with rupture disc and fused plug on hydrogen cylidner is recommended or not?