ISS: Both regenerative CO2 scrubbers have shut down

ISS: Both regenerative CO2 scrubbers have shut down

However, the cabin volume provides a week of 'coasting',
and there are expendable LiOH canisters also available,
and both the Vozdukh and CDRA have encountered
'known' anomalies that are in both cases almost certainly repairable.

Just reminding us all of the 'on-the-edge' nature of TRUE exploration!


official NASA PAO release

NASA Space Station Status Report 18 August 2005



snip The Russian Vozdukh carbon dioxide removal system has been shut
down since last Thursday, and Russians specialists are working on a recovery
plan. Meanwhile, the Carbon Dioxide Removal Assembly in the U.S. portion of
the Station, which has been scrubbing the Station's air since Vozdukh's shut
down, failed early this morning due to a stuck check valve, the latest
instance of a known and understood problem. It is being managed back to
operation by flight controllers in Houston, who reported to the crew that
carbon dioxide levels on board ISS are well below the levels that would pose
any danger. Plans call for Krikalev to do troubleshooting on Vozdukh
starting tomorrow.



(the following courtesy spaceref.com)
ISS On-Orbit Status 18 August 2005 -- All ISS systems continue to function
nominally, except those noted previously or below.snip


Last night at ~6:14pm EDT, the Lab CDRA (Carbon Dioxide Removal
Assembly) failed due to a check valve in adsorbent/desiccant bed #2 stuck
open. This is a known failure mode of CDRA. With the Russian Vozdukh also
down, there is currently no automatic CO2 control. The CDRA will remain
deactivated until after the EVA, at which time it will be restarted in
single-bed mode until the check valve reseats, allowing return to dual-bed
ops. CO2 levels will remain well below limits during the time the system is
off.

"Jim Oberg" wrote in message
...
Last night at ~6:14pm EDT, the Lab CDRA (Carbon Dioxide Removal
Assembly) failed due to a check valve in adsorbent/desiccant bed #2 stuck
open. This is a known failure mode of CDRA. With the Russian Vozdukh
also
down, there is currently no automatic CO2 control. The CDRA will remain
deactivated until after the EVA, at which time it will be restarted in
single-bed mode until the check valve reseats, allowing return to dual-bed
ops. CO2 levels will remain well below limits during the time the system
is
off.

At what point do they get desperate and start hitting the stuck check valve
with a wrench? :-)

Only half kidding though. There are times when a bit of percussive
maintenance is in order.

Jeff
--
Remove icky phrase from email address to get a valid address.

15:00 gmt ISS status report (NASA TV). CDRA is now working again..



"Jeff Findley" wrote

At what point do they get desperate and start hitting the stuck check
valve
with a wrench? :-)

Only half kidding though. There are times when a bit of percussive
maintenance is in order.

Jeff

Jim Oberg wrote:

15:00 gmt ISS status report (NASA TV). CDRA is now working again..

The question that should be asked: what is the longest period that CDRA
has been able to operate continuously without breaking down ?

Seems to me that CRDA spends most of its life shut down with Vozhduk
doing all the work.