The examples of transportation venting displayed today have all been individual pipes. Do you recommend against manifolds? If they are used, what considerations should be taken into account?

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 header and this manifolding is an acceptable practice provided that the design is done properly. It is important to design the header sufficiently large to be capable of handling the combined flow of the devices. These devices are primarily for fire protection and it’s likely that many, or even all, of the vessels would be exposed to fire at the same time.

It is common for LH2 transports to have all the relief devices/bleed valves connected to one vent stack.