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.
EPSA SUPER-COMPRESSOR FAQ
Are all Super-Compressors dual-crown, internal bezel watches? No. Super–Compressor refers to the method of case
sealing and nothing else. Dual crown styles are the most commonly seen, but there are single crown cases that have the Super-
Compressor designation.
Are the large case dual-crown models called “Super-Compressor” and the small case models simply called
“Compressor”?
No. As stated above the term “Super-Compressor” refers only to the case sealing method. Both the small cased
models (36mm) and large cased models (42mm) of the dual crown style are Super-Compressors.
What are Compressor and Compressor 2 types, and how are
they different from the Super-Compressor?
From what I've
observed regarding the various Compressor type watches I have
seen and what I’ve been able to translate from this advertisement,
both the Compressor and Compressor 2 types have snap on case
backs. Compressor 2 types use a shaped case (i.e. square,
cushion or tonneau), not round. Compressor and Compressor 2
watches while water resistant, are commonly seen in "fashion"
watch styles, and while designed to be water resistant are not dive
watches. The exception to this is the triple-crown Compressor
cased JLC Polaris.

The Super-Compressors use a screw-on case back, excepting the
Enicar models which use a bayonet mount caseback. The Super-
Compressor designation is used on both single and dual-crown
types.
Do all Super-Compressors have a screw-on case
back?
Many of them do, but not all. The
Super-Compressor cases manufactured for the Enicar
Watch Co. are the exception. They use a bayonet mount
for the case back, similar to the way a camera lens
mounts.
Are all dual-crown, internal bezel watches EPSA Super-Compressors? No, similar styles were produced by a number of
other manufacturers. I have seen dual-crown internal bezel watches that are very likely EPSA manufactured cases, but do not
employ the S-C technology for the case back.
(SEE HERE)

Dual-crown replica watches have recently begun to appear on ebay. These watches have a number of Super-Compressor design
details like cross-hatched dual-crowns and an internal bezel, but are modern/new manufacturer replicas, not authentic Super-
Compressors.

How do I identify an EPSA dual-crown Super-Compressor? EPSA S-C watches can usually be identified by the trademark
dive helmet inside the case back, sometimes on the outside of the caseback. Dual-crown S-C watches typically (but not always)
have cross-hatched crowns, sometimes you’ll see the manufacturers signature with the cross-hatching behind. With few
exceptions, the crowns are characteristically fat and chunky. If it's a screw on case back there should be a spring assembly inside
the caseback rim. Every dual-crown S-C I've examined has the upper crown located at 11 minutes and the lower crown at 19
minutes on the case, regardless of the case size or style. EPSA Super-Compressor Brevet (patent) numbers may also be present:
Screw-on case backs carry the numbers 317537 and 337462. Bayonet mount (Enicar cases) case backs have the number
314962.
Here's a Zodiac Sea Wolf (above) in a single crown Super-Compressor case. Note the Super-Compressor Brevet numbers and
trademark dive helmet. 3-72 is the date of manufacture. This case was rated to 75 ATM and used by a variety of watch companies.
This small case (36mm) Hamilton seen above is the Super-Compressor type, as is the large case (42mm) Droz seen below. Note
that both have the Super-Compressor trademark and Brevet numbers 317537 and 337462.
This JLC Polaris has a snap-on case back and is
identified as a Compressor type. The watch has three
crowns and an acoustic alarm. Note the Brevet number
313813 for Compressor cases.
Note the three lugs on the case back and the three
engagement points on the case. This watch is also
interesting as I have only seen crown lugs and PVD
finishes on Enicar manufactured Super-Compressors.  
The case back on this dual-crown Longines doesn't have the helmet logo, but does identify it as a Super-Compressor and shows
the correct brevet numbers. The S-C spring and collar assembly can also be seen.
Alpina
Baylor
Benrus
Blancpain
Bucherer
Bulova
Clarna
Consul
Cupillard Rieme
Delvina
Droz
Duval
Duward
Edox
Enicar
Exona
Felca
Fortis
Girard-Perregaux
Glycine
Hamilton
Invicta
IWC
Jaeger-LeCoultre
Le Cheminant
Lip
Longines
Lusina
Milber
Nivada Grenchen
Olma
Onsa
Orsa
Precimax
Renis
Rona
Solix
Solvil Titus
Suter
Talis
Technos
Tissot
Universal Geneve
Unver
Wittnauer Geneve
Zenith
ZentRa
Above is a Bulova Super-Compressor in 26mm
women's size.
Cross-hatched crowns on a large case
Droz.
Dive helmet logo and brevet numbers
on the outside of a large case Bulova.
Dual-crown S-Cs were typically rated
to 600 ft. Bulova stretched the number
to 666 ft, as that was a trademark
depth rating for most of their dive
watches.
Dive helmet logo on a large case
Fortis.
"Small" crowns with the Enicar signature over crosshatching.
BREVET (PATENT) NUMBERS

Brevet numbers I've seen are as follows.

Super-Compressor (below), screw-on case back, both dual-crown
and single-crown, all sizes:

BREVET 317537
BREVET 337462
Super-Compressor (below), bayonet mount case back, dual-crown,
all sizes:

BREVET 314962
NOTE: The information collected here is based on personal observations and the shared knowledge of fellow collectors. Some of
the images seen here have been collected from various internet auction sites and watch forums. If I have used a photo of yours, I
thank you.
Compressor (below), snap-on case back:

BREVET 313813
How may different sizes of dual-crown cases were
offered?

Commonly seen are the large case dual-crown which is
42mm and has 22mm lugs, and the small case
dual-crown which is 36-37mm and has 18-19.5mm lugs.

I have also seen a small number of ladies sized
dual-crown S-Cs which are 26mm.
NOTE: The bayonet mount dual-crown Enicar cases
(below) are commonly referred to as
Super-Compressors, but they carry a different brevet
number and do not display the Super-Compressor
signature typically seen on the screw back models. If
any EPSA trademarks are present, it is the dive helmet
logo and they are marked "SWISS CASE".
Where can I get case parts for a dual-crown
Super-Compressor?

A number of critical parts which are specific to the dual-crown S-Cs
are nearly impossible to find. Crystals are specific to each case
design, and there were many different styles. The internal bezel is
held in place by the crystal and tension ring, and these were
manufactured specifically for these watches. I have heard of
instances where generic crystals were fitted, but with less than
satisfactory results.

The star gear which turns the bezel is not available. Cross-hatched
crowns are not available. Generic crowns can be substituted, but
value points will be deducted from any watch not having correct
crowns.

When considering any dual-crown S-C for purchase, make sure it's
complete and operating correctly. If you've got one that needs
parts, you may have to find a parts-grade watch (maybe more than
one) to get what you need.
How many different manufacturers used
dual-crown Super- Compressor cases?

Dual-crown Super-Compressor cases were very
popular and used by many watch manufacturers, from
the very best like JLC, Zenith and Longines to relative
unknowns.  Here's a list of companies know to have
used the dual-crown Super-Compressor case, compiled
by Dave at the MWR Forum.
How exactly does it work? There are a number of US Patents filed under the name E. Piquerez for a “FLUID-TIGHT" watch case:

US 2,737,009        US 2,737,010        US 2,959,911        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.  

It’s important to note the appearance of the spring assembly inside the S-C case back, as this will help you in the identification of
these watches. I've identified three different spring assembly types, all used under the Brevet numbers 317537 and 337462. Cases
with bayonet mount case backs (Enicar) do not always have a spring.
Type 3 is a corrugated flat spring, used on single crown S-C
cases and bayonet mount cases.
Type 1 is a wire spring held in position by a collar with 4 slots.
The spring wire is visible in the slots. Used on dual-crown
screw back only.
Type 2 has a collar with a single slot. The spring cannot be
seen in the slot. Used on dual-crown screw back only.
For comparison here is a bayonet mount caseback. These do
not always have a spring.
Above is a CYRYN dual-crown that the seller listed as
32mm. This is a Compressor (not a Super), there is a
Compressor signature on the dial and case back. In the
picture below you can see it's a snap-on case back and
Brevet number 313813 is seen.
Here's a rare one: A very handsome Lemania in a single-crown Super-Compressor case. It's a screw-on case back with the EPSA
dive helmet logo and brevet numbers 317537 and 337462.