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Hydrogen and submarines, several observations It use to be general
practice to allow a small percentage of hydrogen to build up within the submarine’s
hull while charging batteries along side the pier with hatches open. Some
one would light a match to “flash-off” the accumulated gas and the problem
went away. A fast, hot rush of momentary fire would flash through the
boat burning off the hydrogen supposedly without causing harm. While the
web site referenced previously stated 4% was explosive, I have previously seen
the number 3% quoted as a teen while experimenting with splitting water into
hydrogen and oxygen with a battery. At that time, I confirmed by
experimentation that small quantities of 3% hydrogen and air mixture would
explode with a nice loud snap from a spark. Back to subs, I believe it
was the diesel boat USS Guittaro charging batteries along side the pier and the
“flash-off” caused severe burns to personnel and started a fire.
This method of charging was no longer allowed after this accident. More
recently the USS Barbel, one of our last diesel boats had a battery fire from a
hydrogen accumulation that was severe enough to result in her decommissioning. The older Johnson Sea
Link battery pods had a patented vent system for their lead acid batteries that
were kept at ambient sea pressure. The battery pods were rectangular in
form and covered by a clear, dished plastic cover. The battery air space
was filled with oil and capped with vented closures. The pods were also filled
with oil. At the apex of the dished cover was a one way valve to allow
gasses to vent off but salt water could not enter. I don’t know if
they are still using this technique. Other research and
commercial subs use battery pods similar to the K-350. The intent with
many of these were so that the battery banks could be quickly slid out and
exchanged to get the boat back in the water where it made it’s money.
It also allowed the batteries to be charged outside the pods so that hydrogen
accumulation was not an issue. The old Tekna scooters
original charged the batteries in the housing without venting. Early on
in the first units, there were some housing explosions so several round disk
hydrogen catalytic converters were placed inside the housing. After a few
more explosions, a large belt of hydrogen absorbent material was placed in the
housing. More explosions (the belt’s effectiveness was negated with
exposure to water) and the scooter design was modified so the nose was
removable for charging. Personal experiences
with hydrogen explosions related to batteries involve two incidents that
occurred due to different reasons. The old Ikelite high-powered NiCad
Modular light (about the size of an old 1 pound coffee can) would allow
charging in the casing when the lens was removed. After a charge, I
replaced the lens and snapped it down with the restraining straps. Had to
check for leaks in a void that was being filled below a bunk on a square
rigger. As I looked under the bunk, switched on the light, and an immense
explosion took place. I flew back, my right hand in great pain, people
screaming at me as to what happened but I couldn’t hear them as I was
momentarily deafened. Initially I thought there was an explosion in the
void but upon inspecting the light, found the lens blown off and cracked along
with the restraining straps bent straight out. After talking with the
engineers at Ikelite, determined that there was a hydrogen explosion, they
replaced the lens and straps, and the light worked for many years after (only
with battery packs charged outside of the housing though J ). The second incident
occurred early in the dive year off of MORAL OF ALL THIS…I
WILL NOT CHARGE BATTERIES IN THE SUB! Maybe in the pods since they are
designed to deal with an explosion |