J. Clarke wrote:
In article ,
says...
Tim Wescott wrote:


I thought it was pure oxygen at high pressure or in liquid form that was
so very dangerous -- does this hold for oxygen at 40 psi?

LOX is the worst, as it is insanely concentrated. But, even pure
O2 at STP is pretty dangerous stuff. They've had some horrible fires
in operating rooms where pure oxygen the patient was breathing was allowed
to spill on surgical drapes and such and got ignited possibly by a
static discharge. You can't put that kind of fire out with a fire
extinguisher until all the oxygen is used up. The Air Force did some
testing just after WW-II to make sure pilots could operate long-term
while breathing pure O2. They had a chamber with a bunch of guys living in
pure O2, and had a fire when a guy changed a burned-out light bulb.
When the porcelain light socket started dripping flaming porcelain onto an
asbestos fire blanket and the asbestos caught on fire, they popped the door
open and escaped.

Nice story. Both porcelain and asbestos are fully oxidized--they will
not burn in oxygen--neither will glass--all are silicon dioxide. If you
don't believe me, take an oxyacetylene torch to a coke bottle and see if
you can light it. The news story I found doesn't mention either
asbestos or porcelain--it mentions that their clothing caught fire,
which is perfectly reasonable if it wasn't made from a fireproof
material. It also says that they were out 40 seconds after the fire
started and that they escaped by breaking a port with a hammer.
http://news.google.com/newspapers?nid=1873&dat=19670204
&id=Z28eAAAAIBAJ&sjid=o8kEAAAAIBAJ&pg=791,11880 11

As a result of the Apollo 1 spacecraft fire, the use of a pure oxygen
atmosphere during launch and ascent of Saturn V was abandoned by the U.
S. space program, according to NASA.

According to the Apollo Lunar Surface Journal, for Apollo 12, values
given for cabin pressure are 4.8 psi, and for normal operating suit
pressure, 3.8 psi. This suggests a pure oxygen environment for the Lunar
Module.

For Apollo 11, 12, & 14, during EVA preparation, the suit relative
pressures were 4.6 to 5.2 psi when the LM cabin pressure was 3.5 psi,
giving suit absolute pressures of 8.1 to 8.7 psi pure oxygen. At
earth's atmospheric pressure of 14.7 psi, this correlates to 55% to 60%
oxygen content, which gives an oxygen partial pressure of 8.1 to 8.7 psi.

According to the Apollo 12 ALSJ, the suits were already difficult to
bend at 3.8 psi relative pressure (when the LM cabin pressure was 3.5
psi). When the suit pressures were at about 4.5 psi relative pressure,
the suits were very stiff.

The following quotes are from a March 11, 1968 Aviation Week & Space
Technology article headlined "Flammability Tests Spur Two-Gas Apollo".

"Washington - Decision to use a two-gas atmosphere (60% oxygen, 40%
nitrogen) during manned Apollo on-the-pad preparations and in
pre-orbital flight reflects a basic inability to make the spacecraft
flameproof after 14 months of redesign that cost more than $100 million
and added about 2,000 lb. to the system.

"The decision (AW&ST, Mar. 4, p. 21) was forced on the National
Aeronautics and Space Administration after three series of flammability
tests on an Apollo command module boilerplate failed to satisfy
officials that changes would prevent the spread of fire under a
pure-oxygen environment."

The article goes on to mention how a 95% oxygen system at 6.2 psi which
would be orbital configuration developed problems in fire propagation tests.

Would not there have been serious flammability problems of such an
environment in the lunar module? The article concludes:

"By switching to a two-gas system for pre-flight and immediate
post-launch activities, NASA is willing to accept an added problem.
Astronauts will be breathing pure oxygen during that phase and they will
have to vent the spacecraft cabin during boost to orbit and repressurize
to 6 psi with oxygen to permit them to remove their helmets and work in
relative comfort.

"Possibility of the 40% of nitrogen causing bends if an emergency escape
has to be made during the launch phase was considered by officials less
hazardous than that of fire propagation in a one-gas system."

A Feb. 6, 1967 article in AW&ST indicates that when the Apollo program
was being planned, the primary reason for choosing a 5-psi cabin oxygen
system was weight considerations. Added weight (with a two-gas system)
would come from a mixture control system to keep the proper gas ratio.
Also, introduction of an oxygen-nitrogen or oxygen-helium environmental
control system for Apollo would have meant the addition of an airlock.

Just how dangerous was a pure oxygen environment in the ascent and
descent lunar module considered to be?

Here on earth, increasing the percentage of oxygen to slightly above 21%
dramatically increases probability of fires. According to The Anthropic
Cosmological Principle (p. 567) by Barrow and Tipler, "...the
probability of a forest fire being started by a lightning-bolt increases
70% for every 1% rise in oxygen concentration above the present 21%.
Above 25% very little of the vegetation on land would survive the
fires...". "At the present fraction of 21%, fires will not start at more
than 15% moisture content. Were the oxygen content to reach 25%, even
damp twigs and the grass of a rain forest would ignite."(p. 568).

Ralph René, in his book NASA Mooned America, provides a list of
government-sponsored testing that resulted in oxygen fires. René
extracted this information from Appendix G in Mission To The Moon by
Kennan & Harvey. Here are some tests on that list:

"September 9, 1962 - The first known fire occurred in the Space Cabin
Simulator at Brooks Air Force Base in a chamber using 100% oxygen at 5
psi. It was explosive and involved the carbon dioxide scrubber. Both
occupants collapsed from smoke inhalation before being rescued."

"November 17, 1962 - Another incident using 100% oxygen at 5 psi in a
chamber at the Navy Laboratory (ACEL). There were four occupants in the
chamber, but the simple replacing of a burned-out light bulb caused
their clothes to catch on fire. They escaped in 40 seconds but all
suffered burns. Two were seriously injured. In addition an asbestos
'safety' blanket caught fire and burned causing one man's hand to catch
fire."

"April 28, 1966 - More Apollo equipment was destroyed as it was being
tested under 100% oxygen and 5 psi at the Apollo Environmental Control
System in Torrance, CA."

"January 1, 1967 - The last known test was over three weeks before
Grissom, Chaffee & White suffered immolation. Two men were handling 16
rabbits in a chamber of 100% oxygen at 7.2 psi at Brooks Air Force Base
and all living things died in the inferno. The cause may have been as
simple as a static discharge from a rabbit's fur ... but we'll never know."

NASA subjected Grissom, White and Chaffee to over 90% pure oxygen at
over 16 psi in a test with live electrical circuits and switches being
thrown, and with a hatch that took more than three minutes to open,
resulting in the fatal Apollo 1 fire.

Bill Kaysing, in his book We Never Went To The Moon, states, in Chapter
9 titled "Murder By Negligence On Pad 34", "If any two documents lend
credibility to the contention that the Apollo flights were faked, they
are most certainly the Baron Report and the Phillips Report. They were
authored by two men of obvious integrity and dedication. Although from
diverse backgrounds, both Tom Baron and Sam Phillips were in total
agreement on one basic premise, i.e., that North American Aviation and
its sponsor, NASA, were totally unequal to the task of assuring even one
successful flight to the moon!"

Why did NASA decide to subject Grissom, White and Chaffee to more than
90% pure oxygen at over 16 psi in a test with live electrical circuits
and switches being thrown, and with a hatch that took more than three
minutes to open, resulting in the fatal Apollo 1 fire?
--
Steve W.