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:

1. Deflagration pressure is proportional to operating pressure
2. Deflagration pressure is inversely related to initial temperature
3. Deflagration pressure is based on concentration and H2/O2 ratio
4. In general, an internal deflagration is unlikely to exceed about a 10…

Exhaust systems (sometimes referred to as ventilation systems) are used to exhaust hydrogen and air mixtures. Normally these are used to vent streams with less than flammable range hydrogen in air.

That is, hydrogen detectors trigger venting or the ventilation systems runs during all hydrogen operations. In these instances, low concentrations of hydrogen are expected, but deflagration is…

Yes, there are differences due to the differences in the fluid properties. We’re not sure what is meant by blowdown. If this means that should the gases be vented to a vent stack, possibly, but for certain these need to be vented to a safe location.

There is currently a published ASME BPV Code Case describing pressure design requirements for pressure design of electrolyzers. If the Code Case is adopted by the jurisdiction where a new electrolyzer will be installed, the new electrolyzer will have to meet the requirements in the Code Case. The responsible ASME committee is working to revise the Code Case and intends to incorporate the Code…

Applicable EU Directives frequently include the following:

·        Low Voltage - 2014/35/EU

·        Machinery - 2006/42/EC

·        Electromagnetic Compatibility - 2014/30/EU, EMC

·        Pressure Equipment - 2014/67/EU

·        Restriction of Hazardous…

When it is necessary or desirable to work on a part of a hydrogen system while another part of the system remains in operation or in standby condition. An example is a system with two compressors, where one is normally operating and the other acts as an installed spare. The two block valves are closed, and the bleed (vent) valve is open. This arrangement assures that any hydrogen leaking…

The SRV orientation is critical for many reasons. Many of these are:

1. Manufacturer recommendations – Manufacturers may require a certain orientation based on the internal design.
2. To ensure no back pressure changes the setpoint beyond allowable design
3. To ensure moisture does not enter the relief device. This is critical for the operation for LH2 and also for GH2 (in…

The ASME BPV Code, and other Codes by reference, require less than back pressure of 10% of device set pressure from the release flowrate for proper operation of reclosing relief devices such as relief valves. Backpressure from non-reclosing or non-ASME devices may be higher so an analysis is required. It’s not enough to assume the vent system need only be designed for 10% of the set pressure.…

Vent stacks and building ventilation systems are different and should be analyzed/designed differently. NFPA 2 has different location requirements for vent stack and ventilation system outlets. There are code requirements for elevation, distances from exposures, and between exposures. 

There are no specific regulatory or code requirements for vent system separation distances. These…