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Not being a physicist nor scientist, I look at SL as a cavitation " event".
Back in the 1970's a friend asked me to study a piece of 4" copper pipe removed
from a high rise apartment building's water supply house pump discharge. The
copper pipe was 4 ft long and the top side of the pipe was completely open. The
remaining portion of the pipe interior appeared to be " shot-peened" by
buckshot.The severe cavitation erosion occurred in one short part of the early
morning hours.
The pipe was connected to the discharge side of a pressure reducing valve.
During the night as water demand fell to nearly zero, the regulating valve ahead
of the copper pipe, maintained a regulated downstream pressure against the
building riser head pressure. The globe style valve worked at its maximum lowest
range created a sonic noise by barely being off the valve seat.
This sonic effect is well known in valve applications to cause cavitation and
seat " wire draw". Although the building was almost new, no events as described
had previously occurred. Some of the investigations uncovered a report by a
tenent on the 11th floor that said her dog almost went crazy that early morning
from the wierd sounds in the wall ( the wall housing the water pipe riser). A
chemist friend suggested the event may have been related to chlorination of the
water. In checking with the City of Houston, they reported they had
hyper-chlorinated at the local water booster station a night prior. In my
experience, I have never before nor since, encountered a like event. I have seem
large split case centrifugal pump bronze impellers that appear "rotted" from
cavitation caused by improper sizing of the suction piping.
My next true experience with cavitation came some 7 years ago with a high
speed rotating member being returned from a plant in California. The UHMW poly
material was severely eroded adjacent to each vacuum producing cavity
and appearing to be punched with a extremely sharp pick some 3/8" deep. The
reports that came back to me included a comment they decided to try reversing
rotation to find if a better mix would result. They were inducting a standard
hypochlorite 15% solution thru the member.
The point of this post is to suggest that chlorine may have a place
in examining SL events. I asked Dr.Putterman some years back about some of
his tests and he indicated they tried a thin piece of copper plate in their test
and the SL bubble made an " indent" in the plate.
Richard
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