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No, but it is always necessary to determine the possibility of an adverse chemical reaction with the particular material being used for the mesh.
The Panel has not received such inquiries. Section 14.2 of NFPA 69 Standard for Explosion Prevention Systems covers foam and mesh requirements. NFPA 69 states in 14.3.4 that the tests shall be conducted with a flammable gas/air mixture with a fundamental burning velocity representative of the burning velocities of flammable vapors expected in the intended applications.
Explosion testing with hydrogen should be utilized only where there is not an established alternative and then only by personnel experienced in such testing.
Testing with hydrogen is always a challenge and needs to be approached carefully due to significant differences in properties between hydrogen and propane. Hydrogen can develop significantly higher overpressures and preliminary…
There are two parts for such a system to be effective. First, the system would have to activate quickly enough to establish a water mist throughout the region of interest (i.e., region occupied by a flammable gas mixture) before it could be ignited. This is challenging in terms of timing, and the impact of spraying water inside an enclosure filled with equipment not designed to get wet can be…
The design of vent systems is critical to the safety of the system. From a process perspective, the pipe design must be sufficient to withstand back pressure, internal pipeline pressure, deflagration pressure, thrust forces from the flow, and must be of a sufficient size to not create a restriction that prevents proper flow or activation of the devices.
The vent system…
It is best to avoid planned blowdown of large amounts of hydrogen inventory at high flowrates if possible. Low flow releases from vent systems are normal and occur for purging, delivery operations, and maintenance activity. A challenge with high flow blowdown of a hydrogen system is that venting large quantities of hydrogen can itself be a hazardous activity. …
Welded systems are generally preferred, where possible, to reduce the likelihood of leaks. Generally, even welded systems will need non-welded joints (e.g. unions, flanges, etc.) to allow maintenance replacement of components. A low-pressure system would not be an exception to this preference. However, piping at lower pressures and smaller sizes will…
There are several concerns with “snuffing” a hydrogen fire from a vent stack. Most importantly, snuffing a hydrogen fire before the hydrogen is isolated can lead to the buildup of a hydrogen vapor cloud, which may then re-ignite, especially with hot surfaces available from the previous fire. The largest hazard is an explosion of the vapor cloud…
TIA 1783 points out a valid concern about how to address the electrical classification zone around a liquid hydrogen system. The existing requirements specify 3' around the outlet of the stack for Division 1 and 25' around the outlet of the stack for Division 2 area. These distances are historical and date back to the 1960's. They are a "one size fits all" simple approach that is easy to…
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