Hmmm. I do not think this proves it!

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Posted by Wayne on October 02, 2000 at 15:47:35:

In Reply to: EINS, this on is for you , now pay up!!!!!!!!!!! posted by MHK on October 02, 2000 at 09:33:15:

Here is the problem. In any discussion of dive related issues, such as the compressibility of certain exposure suit materials, terms such as "compressibility" must take on realistic values rather than simply absolute digital definitions. It may be that the material in question is "compressible" as "divers" would define the word. That cannot be answered with the writing cited. Additional data showing that the factor used is applicable to compressed neoprene would answer the question better than the formula used to calculate it.

The problem with simple use of the term "compressible" is the only issue I wanted to address. I would have felt better all along if you and Eins had inserted a word such as "appreciably" in front of the word compressible. For example WATER is compressible. At 32 degrees F (0C) water's volume is down to a measly 0.9769 of its original amount at 500 atm. At 5000 atm the water is only 0.8565 of its origninal. At higher temps even more cool stuff happens since the volume of water is influenced by temperature so that at 68 degrees the original volume is up to 1.0016 at the surface and 0.9804 at 500 atm and 0.8675 at 5000 atm. SO WATER IS COMPRESSIBLE. But in terms of diving, it is incompressible because its compressibility is not significant under the pressure changes experiences in SCUBA diving.

So anyway, I am still awaiting the data on compressibility of crushed neoprene. And before the check is written, I hope the answer is given in terms of appreciable compressibility as that applies to Recreational or Tech Scuba Diving as done here in California. I do not know how I would define this. Probably some fraction of the change in buoyancy caused by normal breathing would be a good definition. Maybe a couple of pounds in a suit shell?

Just my thoughts and hope for a good FRIENDLY discussion that allows us all to learn more about the science of the world we love so much!


For the interested types. These were all guage pressures and pure water and are taken from "International Critical Tables" as republished in "General Properties of Materials" by Howard S. Bean, Late Physicit, National Bureau of Standards in "Marks' Standard Handbook for Mechanical Engineers" Eighth Edition.

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