I found this to be an interesting read about this patented technique for water sealing watch casebacks. The original content can be found at: http://www.scubawatch.org/EPSA_SC_FAQ.html
-- Awesome site!!What is a “Super-Compressor” dive watch?
“Super-Compressor” refers to a patented case sealing method developed by
watch case manufacturer Ervin Piquerez S.A. (EPSA). The design takes advantage of the water pressure the case is exposed to
at depth to press the case back against the o-ring seal . More depth equals more water pressure equals greater seal. Dual crown
Super-Compressor watches typically have a depth rating of 600 ft. This same concept was employed by Omega in the Naiad
crowns used on Seamaster 300 watches in the ‘60s.
Well regarded as being very high quality and watertight, EPSA manufactured the S-C cases in a variety of styles from the late '50s
until bankruptcy closed the business in the mid-'70s. The fact that so many survive today is a testament to their quality.
A few pictures of a 1970's Zodiac Sea Wolf in a single crown Super-Compressor case:
Cool diagram that illustrates it:How exactly does it work?
There are a number of US Patents filed under the name E. Piquerez for a “FLUID-TIGHT" watch case:http://www.freepatentsonline.com/pdf_collections_server1/uspt/patent_pdf/2737/US2737009/pdf/US2737009.pdf?k=257afd2a3d6a531f4ec6bbb44a4d045d
- US 2,737,009 http://www.freepatentsonline.com/pdf_collections_server1/uspt/patent_pdf/2737/US2737010/pdf/US2737010.pdf?k=fd445cb4e3e5dd870b4283e13adf0c1c
- US 2,737,010 http://www.freepatentsonline.com/pdf_collections_server1/uspt/patent_pdf/2959/US2959911/pdf/US2959911.pdf?k=c4743dd2ab1a99d8c71857eab7a48d78
- US 2,959,911 http://www.freepatentsonline.com/pdf_collections_server1/uspt/patent_pdf/2968/US2968911/pdf/US2968911.pdf?k=67ac4402403859780d3376f96b33e6c4
- US 2,968,911
These patent documents offer detail as to how the Super-Compressor cases work. As I understand it the Super-Compressor case
back screws down against a spring assembly located inside the rim of the case back. The case back is “tight” before fully
compressing the o-ring gasket, and before the case back flange is tight against the case. This allows the case back to move
inward (very slightly) as it is exposed to water pressure at depth, theoretically increasing the compression pressure on the o-ring
for a more water-tight seal. It also minimizes stress on the o-ring by keeping it at lower compression levels until full compression is
needed. I suppose this would add to the life expectancy of the o-ring.Please note
- This is just a sample of the great information available regarding this process over at Scubawatch.org. If you are interested, there is tons of additional informaiton as well as pictures of super-compressor watches over at that site.