The OPS was activated by moving a lever
attached to the chest-mounted Remote Control Unit (RCU).
The lever had a ring on the end, making grasping it easier.
Detail from Apollo 17 photo AS17-134-20385 of Gene Cernan.
Diagram from the Apollo 15-17 EMU Handbook (vol. I)
showing the OPS actuator.
OPS Actuator Bracket on the side of a training unit,
photographed in October 2006 at the Smithsonian Institution's
Garber Facility by Ulrich Lotzmann and Amanda Young.
(Click on the image for a larger version)
Side view of an installed OPS Actuator.
Photo by Paul Kashuk.
Side view of an actuator
from Apollo 15 training photo 71-H-1123.
Front view of Neil Armstrong's actuator
from training photo 69-H-670
||A12-15 EMU Handbook, Vol.
4.2 and 4.9
||4.2 OPS Operations:
Donning prior to Contingency (LM to CM EVA) Transfer;
4.9 Purge Valve Operations: Activation; Shutoff; Removal
||Extended discussion with
about using the OPS in make-up mode.
||Once the crew was back in
and had the cabin pressurized, they could use the purge
speed depressurization of the suits.
||Cernan - "In addition to
us an emergency oxygen supply in case we'd lost
integrity on one of the
suits, the Oxygen Purge System also gave us another
capability. After the third EVA, we threw the
PLSSs out of the LM
but kept the OPSs so that, at rendezvous, in case we
couldn't dock, we
could use the OPSs to do an emergency transfer-EVA into
Module. We could plug the OPS in directly to the
belly of the
suit and stay pressurized for 30 minutes, long enough to
get into the
Command Module had we had a docking problem." OPS
done before each of the EVAs and before the pre-launch
jettison. If either of the OPSs had failed its
would have kept a PLSS in case they had to do an EVA
transfer to the CM.
||Houston wants to make
and Ed take the '100-foot' tether up to the cabin in
case they have to
do an EVA transfer to the Command Module. Because
problems experienced early in the mission, Houston
believed there was a
greater-than-normal chance of an EVA transfer.
||Mention by Dave Scott of
spend as part of the Apollo 9 crew developing procedures
transfer from the LM to the CM.
||Pre-EVA-1 OPS checkouts and report|
||Post-EVA-1/Pre-EVA-2 OPS checkouts and report|
|Apollo 16||154:15:50||The OPSs are identical but, because the antenna on John's broke during post-EVA-2 ingress and his PLSS is the only one with comm electronics for relaying to the LM or LCRU, they will swap OPSs for EVA-3|
||Extended discussion with
Cernan about the purge valve and its similarity to the
regulator in an aircraft cabin. Also discussion of
failures versus double-mode failures and use of both
OPSs to support
the crewman with the failed PLSS
||During EVA-1 preps, as
checklist, Jim gets his purge valve and verifies that it
is closed and
in low flow before handing it to Dave for
checks his own at 119:19:16,
|Apollo 15 + 17
|After EVA-1, Jim comments
dirty his purge valve is.
After EVA-2, Dave has trouble removing his purge valve. "'Kind a stuck' it is. Guess we got a little dirt in here. Guess we'll have to work on that later."
Gene Cernan mentions a dirty purge valve after Apollo 17 EVA-2.
||Jack reports "Both (OPS)
regulators are reading slightly under 4.0 (pounds per
square inch or
psi)." The expected range is 0.370 ± 0.30
is alerting Houston that both OPS readings are near the
edge of the
||While installing Buzz's
valve, Neil rotates it in the connector to position the
Red Apple so
that Buzz could grasp it easily.
||Prior to EVA-2 Preps,
tells them to be sure that Jack uses the purge valve
with serial number
211 and Gene number 208. Schmitt - "This probably
means that each
purge valve was optimized to a particular suit flow
system, and they
wanted to be sure that we each had the right one.
We had taken
the valves out at the end of the first EVA, and part of
the EVA-2 prep
was to put them back in." CapCom asks them to do
the same prior
to EVA-3 preps. These are the only such instances
lunar surface transcripts, suggesting that this was the
where optimization was attempted. The fact that
use of a specific
purge valve is not in the surface checklist and that no
was made prior to EVA-1 suggests the possibility that
is a response to the higher than expected OPS regulator
pressures. There is no mention of this issue in
the Apollo 17
||At the start of the drive
Station 2, Bob reminds them that we're under a 63-minute
limit to get
you from the LM out to the Station 2 because of OPS
So, keep us informed so we can keep a good tab."
As they are
approaching Station 2 at 142:39:51,
Using the Buddy Secondary Life Support System (BSLSS) to share cooling water and using an OPS in low-flow, they have a 79.5 OPS lifetime. Margins are discussed in the chapter on Emergency Return to the LM.
||Between EVAs and in
for LM liftoff, the purge valves were stowed in the
Bag (TSB or 'purse')
|While Charlie works
Rover at the ALSEP site, he finds John's purge valve pin
on the ground
next to the CDR's seat. It must have come out when
John got off
the Rover. Charlie puts it under John's seat,
to install it before they leave. About a minute
asks Charlie to install the pin before he gets back to
his ALSEP tasks.
Video of Charlie doing the installation at 122:25:42.
John's pin comes out for the second time as he is getting seated at the end of their brief stop at Halfway Crater.
John's pin comes out again while he's getting off the Rover at Station 2. Later, just as they are about to leave Station 2, Tony asks Charlie to make sure John's pin is still in. It is.
During the EVA-1 debriefing, Tony tells them that people are thinking about the problem of John's purge valve pin coming out but adds, "I wasn't sure you had a problem." John replies, "I don't think we've got a problem, either, if I can figure a way to keep (from) pulling it every time I get in and out of the Rover. If I can't do that, why, we'll just keep putting it back in." In an extract from the Apollo 16 Technical Crew Debriefing, John says that, during EVA-2 prep, they turned the purge valve so that the pull-pin and Red Apple was pointing away from his naval. During the suit integrity check, he made sure he could reach the Red Apple, which he could. There were no further problems. Post-mission testing confirmed Charlie's suspicion that John was catching either the red apple or lanyard on his seatbelt while he was getting off the Rover. Photo AS16-114-18388 shows the position of John's Red Apple during EVA-1, just above his right leg; AS16-117-18825 shows it during EVA-3, just below his camera, peeking out behind the sample bags.
During EVA-2 preps, Tony England passes along a suggestion that John use something as a lanyard to secure his Red Apple to a fitting on the front of his suit. John doesn't think much of the idea and ends up not doing anything other than re-positioning the Red Apple. Based on Tony's conversation with the crew during the EVA-1 debriefing and his emphasis that they do 'whatever you think's necessary, he doesn't think much of the idea, either. The Red Apple was easy to spot if the pin did come out.