SFOG failure rate approaches 60%?!?!?

As first reported by Keith Cowing:

NASA Space Station On-Orbit Status 30 May 2005
http://www.spaceref.com/news/viewsr.html?pid=16792 (Keith Cowing's primo
space site)

"Update on Solid-Fuel Oxygen Generator (SFOG) candles: Of the old set, 24
have been used since 5/20 (9 failed), 82 remaining."

JimO: The most recent previous statistical summary was 27 May 2005
http://www.spaceref.com/news/viewsr.html?pid=16772
"Update on Solid-Fuel Oxygen Generator (SFOG) 'candles': As of tonight,
since 5/20 a total of 10 candles have been decomposed on board (total
attempts: 12 [i.e., 2 duds, = 83% success rate])."

My math says that this means in the May 27-30 period, 12 more were used, or
which 7 were duds -- that's
almost a 60% failure rate (5 good ones over a 3-day period is what you'd
expect to keep the 2 guys breathing --
you keep firing them until you get enough.

What is special about this recent dreadfully bad batch? Did they START on
May 20 with the unusually
'best' batch (20% failure rate) and then get into a more typical failure
rate, or is this recent bad run a fluke,
or are the statistics as reported some bookkeeping error or typographical
error?

It occurs to me that the problem (if it's real) might not even be with
the candles, but with the firing mechanism.


"Jim Oberg" wrote
My math says that this means in the May 27-30 period, 12 more were used,
or
which 7 were duds -- that's
almost a 60% failure rate (5 good ones over a 3-day period is what you'd
expect to keep the 2 guys breathing --
you keep firing them until you get enough.

What is special about this recent dreadfully bad batch? Did they START on
May 20 with the unusually
'best' batch (20% failure rate) and then get into a more typical failure
rate, or is this recent bad run a fluke,
or are the statistics as reported some bookkeeping error or typographical
error?

Jim Oberg wrote:

It occurs to me that the problem (if it's real) might not even be with
the candles, but with the firing mechanism.

It is a problem nevertheless.

In terms of failure rates, is this the first time that the crews rely on
SFOGs for such a long time of constant use ? (With progress O2 depleted
and Elektron dismantled).

Do the russians just tell the crew to use an SFOG in box XXX, or do they
provide specific serial numbers of which candle to use ? Perhaps in the
past, sporadic use of the candles resulted in crews using the "best"
candles in a box, whereas now, they have to use every candle in the box
which would change the reliability ratings.

Do the russians assume that all SFOGs will be usable ? If not, then what
reliability rating do they use when calculating how much oxygen is
available through the SFOGs on the station. (and does this reliability
rating match reality, and if not, what is the real autonomy of O2 on the station).

And now, the question americans have not answered: Can the O2 and N2 in
Quest be released into the ISS cabin air, or is the hardware/software to
do that not yet on the station ?

Should the SFOGs run out before the next Progress, Quest O2 is the only
oxygen left, unless they thinker and re-install Elektron.