Status of DDA Technology

If a flame arrester is not certified as meeting the above conditions, it may not function as reqnired (see Chapter 5). 

For mixtnres with component MESGs greater than the test gas, rising a flame arrester that has been certified for any gas or vapor with a lower MESG is conservative (safe) (see Chapter 5). 

A flame arrester mnst not be installed in pipes larger than those dial the arrester has been tested for. When a flame may arrive from a pipe with a diameter larger than the arrester connecdon, the arrester should be installed no closer than 120 pipe diameters from the larger pipe. This allows transient large overpressures and tnrbn-lence produced by die redncdon in pipe diameter to dissipate (see Chapter 5). 

A protected-side restricdon, snch as a valve, can severely reduce a flame arrester s capabilides by magnilying reflected initial pressure on the arrester element. In snch a sitnadon, a downstream restriction should be included in the test protocol (see Chapter 6). 

Many test protocols are not applicadon-specific and do not provide die user with a clear idea of how to select a flame arrester (see Chapter 8). 

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