EPSA Compressor Case

EPSA Super-Compressor / Compressor

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-ringseal. More depth equals more water pressure equals greater seal. Dual crown Super-Compressor watches typically have a depth rating of 150-200m (600 ft.) This same concept was employed by Omega in the Naiad crowns used on Seamaster 300 watches in the ’60s.

Note: Compressor and Super Compressor refers to the case NOT the number of crowns on the case. But most Super Compressor watches have twin crowns and have a hatched pattern on the head. Compressor and Super Compressor cases can be large (42mm) or small (36mm) with 1 or 2 crows. Again the larger cases and those who twin crowns tend to be Super Compressors.

These cases are 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.

Compressor Types:

Compressor: Generally snap back. Less water resistant than the S-C and hence are represented as “fashion” styles and not dive watches.

Compressor 2: Generally snap back. Some use a shaped case (i.e. square, cushion or tonneau), not round. Less water resistant than the S-C and hence are represented as “fashion” styles. I really have not found any concrete definitional differences between 1 & 2… but I am still looking.

Super Compressor: Generally a screw-on back, with the exception of ENICAR that used a bayonet closure mechanism, similar to that used to mount lenses on cameras. As mentioned Super Compressor watches are both single and dual crown.

Note: The bayonet mount dual-crown Enicar cases are commonly referred to as Super-Compressors, but they carry a different Swiss Patent Number (Brevet number) 314962 and do not display the Super-Compressor signature typically seen on the screw back models.

It’s important to note the appearance of the spring assembly inside the Super Compressor case back, as this will in the identification of these watches. There are 3 different spring assembly types; all used under the Brevet numbers 317537 and 337462. Cases with bayonet mount case backs (Enicar) have 314962 do not always have a spring. I think this is because the spring in the case has been lost. But in my experience, the bayonet closure system is more in unison with the Compressor Principle than the screwed back as the bayonet allows for more movement as there are no case back threads to impede movement.

Spring Types:

“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.

Type 3: is a corrugated flat spring, used on single crown Super Compressor cases and bayonet mount cases.”

I have seen the corrugated spring in dual crown cases as well.

Note: The information collected from other sources including www.scubawatch.org.