The potential of an explosive atmosphere is inherent with any vent system and must be addressed through adequate design. Purging for most vent stacks is impractical due to availability or cost. In addition, and particularly for LH2 systems, the purge gas can cause potential safety issues. The primary way that explosive atmospheres are addressed is through ensuring that the design of the vent…
Plugging is a concern before, during, and after a release. Prior to the release, water may accumulate in the vent system from weather conditions (rain, snow, etc.) or from condensation, particularly if there is intermittent flow which causes the stack to get cold. This water can freeze due to ambient conditions prior to a release, thereby blocking the stack. It is also possible for
other…
Yes, small flowrate vents may be invisible, particularly in daylight. Sometimes it may still be possible to see heat striations in the air from the heat generated by the fire, but it can be difficult to discern at low flowrates.
This may be able to be accomplished as a method for ignition. We have not seen it.
As flaring is not usually recommended, especially when timing is an issue, a sparker that takes time to ignite would not be recommended.
A vent system should still be installed in case the flare system does not remain ignited.
Typical practice for gaseous tube trailers is to vent relief devices independently to the top of the vehicle. This is primarily to accommodate the large flowrates and high thrust forces involved from these releases. It’s fairly easy to do this since the vent lines are fairly short due to the maximum road height of trailers. Regulations do not prohibit piping multiple devices into a
single…
A release is defined by the amount of hydrogen, the rate of hydrogen flow, vent location (indoors or outdoors), geometry in the area (confined or not), and pressure.
A small or large release should be differentiated by the damage that can occur because of an ignition. This can be a fire, deflagration, or detonation.
Therefore, the relative size of the release will vary based…
Low-pressure vents at mostly low hydrogen purity are not as large safety risk as high-pressure pure hydrogen vents. These vents should still go to a vent stack, but it will probably be small in diameter and thus the tee vent at the top can be small.
If the purge requires high flow, if purging horizontally, the reaction forces of the flow exiting and the hydrogen cloud should be modeled…
Liquid hydrogen will almost never accumulate in a vent system since vent systems are typically designed without insulation. The extremely cold liquid hydrogen temperature of -420 F.
Additionally, vent stacks on an LH2 tank are connected to the vapor phase of the tank. Only in a few rare instances will LH2 be entrained in the gas stream.
Accumulators are recommended at the bottom of…
The deflagration pressure is dependent upon many variables.
However, some general concepts are:
We are the leaders in the building industries and factories. We're word wide. We never give up on the challenges.