Filling and Purging Requirements for Advanced Media (22)
Criticality: Medium
Progress: Not Addressed
Score: 24
DOT Relevance: §173.302
Description of Key Area
Emerging hydrogen storage technologies (e.g., hydrides, cryogas,
physisorption, and reactives) are being developed to address the low storage
density—both gravimetric and volumetric—of gaseous hydrogen. Certain of these may
require special handling when filling or purging. For example, heat transfer
mechanisms are generally needed to remove heat generated during hydrogen
charging for metal hydride containers. When purging (emptying) packagings
containing hydrogen in advanced media, there could be a potential for a release
of media or an inability to remove sufficient hydrogen (to remove any potential
hazard) without removing the media.
Discussion of Criticality
It is anticipated that as these storage technologies develop,
their proponents will determine any unique conditions or procedures for
container filling and purging. It is also anticipated that as early products
are brought to market, initial regulatory coverage will be via special permits
which will likely require filling or purging to be performed by the
manufacturer or their designated agents, providing a level of control over the
filling or purging processes through manufacturers’ developed practices.
Discussion of Progress
As most storage technologies based on advanced media are not
widely deployed (if at all), progress was assessed as “Not Addressed”.
Recommendations
As development and deployment activities increase, initially the special
permit process could be used to incorporate any special handling requirements
during filling. With sufficiently wider deployment, requirements could be
considered for incorporation into regulatory structures.
Unless a particular filling or purging procedure could result in
the development of a potentially hazardous situation, specific guidance may not
be necessary.
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