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Tip #13 - NFPA 99: Emergency connection

By Chad Beebe posted 02-08-2018 12:46


Emergency Connection

NFPA 99-2012: When an emergency oxygen connection is required on the outside of the building, such as where the bulk cryogenic liquid central supply system is outside of and remote from the building, the emergency oxygen supply connection must be accessible and have a minimum of 3 ft. (1 m) of clearance around it. #ASHEComplianceTip

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03-21-2018 19:34

While not directly addressed by the codes, here are a few additional practical recommendations based on past experience:
  • The code minimum 3' clearance around may be inadequate. For a good sized hospital, backfeeding a bulk tank that is down or being relocated is a significant load, and it is probably not practical to serve with a standard dewar.  To truly back-up a bulk O2 system, a trailer mounted tank may be required.  So plan for parking a trailer, not just a dewar. 
  • Since the repair or replacement of the tank or O2 line could be a while, even this trailer mounted unit may need to be re-filled in the course of the outage.  Therefore, the Med Gas supplier may require the same clearances and concrete pad as if it were the bulk tank itself, even if NFPA 99 does not directly point to NFPA 55 for an EOSC. 
  • In a situation I am familiar with, the Med Gas supplier said that they needed to blow off any remaining LOX before they take back the trailer, since the tanks are not DOT rated for over-the-road.  This created a very impressive plume of O2.  That really wants to have free and clear area around it with no combustible hazards.
  • Don't shortchange the size of the EOSC.  It needs to flow just as much O2 as the permanent line.  
  • Related to the above, to truly feed O2 from a liquid source at the rated expected, an evaporator is probably required.  So again, plan for more room than the code min 3'.
  • I have seen a couple of times where the bulk O2 needed to be  moved or replaced.  This could be a long downtime.  In those cases, the hospital decided they needed to connect the master alarm panel to the temporary trailer.  Alarm connections are not required by code minimum but it is a darned good idea.  Conduit and wire, or at least a plan for such should be considered