Second Flammable Gas Safety Meeting NA58:
-----------------------------------------
date: 21.03.01 10:00 892-1-D20

subject: finalize flammable gas safety system and alarm actions for
	 bld 908, bld 888, bld 888 gas mixing zone, RICH tent and
	 RICH test area

participants: Silvia DALLA TORRE, Jonathan GULLEY, David HAY, 
	      Martyn DAVENPORT, Eric WEISE, Gerhard MALLOT, 
	      Bruno PICHLER

signs:  --  <=>  information
	->  <=>  recommended/prescribed action 

contribution to minutes: 
  i) list of alarm actions: David Hay
  ii) list of recommendations from Martyn Davenport
      -> file attached: "list_FGSO.txt.gz"
  iii) RICH flammable Gas Safety from Silvia DALLA TORRE
      -> file attached: "RICH_flamGasSafety.txt.gz"

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actions in case of gas alarms: 
------------------------------
  list of alarm actions and general system description:
  "888 Gas Detection monitoring - User Requirements Document" by David Hay
  -> updated version attached: "URD_888_GAS_v1.doc.gz"
     (remark: on page 10 should be a little correction: in bld 908 are
      four, not three, racks with flammable gases: Numbers 74, 75, 76 and
      77. Sorry, I was not able to edit the document; always got a error
      message when I tried.) 

  
additional remarks/recommended actions:
---------------------------------------

general:

  -> in case of level 2/3 alarms in 908/888: 
     hard-wired signal ("dry contact"/relay) to NA58 Controll Room
     (see also: list of alarm actions, D.Hay)
     => position of detection head which triggered the alarm is indicated
	on central gas detection controll racks (in bld. 888)
  
  -- non flammable gases supplied by bottles in 908:
     -> to be discussed by/with the concerned groups: Should the flow of 
	non-flammable gases to the chambers be interrupted in case of gas 
	alarms?

  -- the supply of non-flammable gases by the CREN gas distribution
     network will not be affected by gas alarm actions

  -- ex-proved equipment has not to be switched of in case of gas-alarms  
     => not ex-proved equipment can be used in gas zones when it is
	approved by TIS, but has to be switched of in case of gas alarms
     BUT
     -- in case of L3 alarm all power inside zones with risk
	classification of at least 2, has to be swiched of
	(according CERN's flammable gas safety manual)


RICH:

  -- RICH PD CH4 supply shall further on be controlled by PLC in gas
     mixing zone
     => less work to rearange/replan not yet existing equipment
  

gas mixing zone:

  -> install switch (to be controlled by gas detection electronic) to cut
     power 
     only in mixing zone
     (see: list of alarm actions, D.Hay)

  -> use one existing detection head to cover tube-connections to exhaust
     (final ventilation system just need three of the existing and four
	new, sensitive (ICARE-) heads 

  -- in case of flammable gas mixing zone ventilation system fails:
     -> actions: off gas bld 908, off arrival gas in bld 888
	(electro-valves),
		 off 220V, off flow to chambers
     -> ventilation system failiure signal to be integrated in gas
	detection controll electronics 

  -- gas risk classification of ventilation system/ventilated racks:
     -- mixing racks itself: zone 2
     -- air ducts: zone 1
     -- exhaust (outside bld 888): zone 2

experimental area:

  -- no subdivision in different gas zones required by NA58

  -> in case of gas alarms: hard-wired signal to NA58 control room
     (see above and list of alarm actions, D.Hay)
     => HV-supply will be ramped down by NA58 Slow Control 
	(in order to protect chambers, because flammable gas supply will
	be interupted in mixing zone/bld 908)