[FPSPACE] ISS fires three oxygen candles today

[James Oberg]

I need some context on this interesting development.

How many 'oxygen candles' have been used on ISS,
when was the most recent time? This sequence of burning
three per day all week -- is that the largest concentration of
usage ever on ISS?  Thanks.

Today's On-Orbit Status Report notes:
 With the US OGS (Oxygen Generator System) currently down, 
Gennady in the course of the day ignited three SFOG 
(Solid Fuel Oxygen Generator) "candles" in the RS...

Yesterday's report:

ISS On-Orbit Status 08/10/09 
   The FE-4 [Bob Thirsk] accessed & serviced the OGS (Oxygen Generation System) rack, first removing equipment on its right side, then configuring the OGS equipment for activation by the ground. After the OGA (Oxygen Generation Assembly) had been powered for 20 minutes, Bob was to reconnect the H2 [hydrogen gas] sensor QDs (Quick Disconnects), close the rack door, re-attach the WDS (Water Delivery System) and replace the equipment on the right side. [After starting the OGA at a processing cycle at the 25% production rate to check offnominal operation (unusual pressure drop), ground controllers moded the unit to 100%. At this point, the OGA water pump delta pressure approached the FDIR (Failure Detection, Isolation, & Recovery) upper limit shutdown criteria (a problem which has occurred previously) which caused ground controllers to deactivate the unit again. Specialists will develop a forward plan.
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