After our success with the pump and the small closed
loop we needed to see if it could pump water through
all the equipment we were likely to use in the refrigerator
and the suit. All in all, that amounts to about five
or six metres of tubing. We filled the tubes with water
and connected up to the type of device that we might
use in the fridge and tried it out. Nothing happened.
Tried it again, still no joy. Ellen even tried to blow
the water through the system and found she couldn’t
do it so our little pump would have no chance.
So we needed another plan to try and solve the problem.
They filmed us chatting about other possible ways of
pumping and we talked about perhaps using the foot pumps
that were lying around.
Then it occurred to us that there might be an air lock
in the system. We had tried to fill the tubes as best
as possible but in all the bends and coils of tubing
it is possible that there might be air trapped in one
of the bends. So we carefully sucked water into the
system and poor Ellen and I ended up having to drink
quite a lot of it. After playing around for ten minutes
or so we gave it another try and it worked! It was slower,
of course, but we could see some small air bubbles passing
really nicely through all the tubing. Ellen put some
red dye into the water so that we could see it better.
There were still problems with the pump, though. For
one thing, not all the rollers were identical and sometimes
the drill would stall if the machine squashed the tube
too much. We took it all apart to try and make the whole
things more symmetrical and this helped. We then tracked
down the cause of the problem to the tube itself. Yesterday,
when the pump seemed to work so well it was really hot,
and we had been filmed in the afternoon. All this time
the equipment was in the Sun; consequently the tubing
and the water were nice and hot and so this kept the
tubing very flexible. Today it was cooler and the water
is cooler and so the tube is stiffer - enough to jam
Once we had warmed the tube up it all worked well.
It should be very hot in Death Valley so the tube should
be nice and flexible - but of course we are aiming to
pump cool water through the system so how will this
affect the tube?
Kathy's first experiment didn’t get a good enough
pressure / vacuum to cool the water. Found an air leak
via the thermocouple wiring and after a few other mods
we were getting 60 % atmospheric pressure / vacuum (roughly
400 Torr) which is pretty good for the simple equipment
we were using. However still no joy getting the zeolite
to do anything and the water just sits there; no cooling…
A really good Rough Science test though.
There is still so much to do for this experiment that
we bring equipment back to the rooms and have a takeaway
and a drink and carry on. Mike B starts work on another
method of cooling the fridge.