Officine Panerai

BDLJ
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Explanation

Hi Patrick,

DRMW covered most of it, but here's my editorial.....

The HRV is for Saturated Diving, which mainly concerns commercial or research diving. It has nothing to do with the depth rating of the watch. And while an interesting feature, it's unneccesary for 99.999% of divers, not to mention desk-divers.

In Sat Diving, you live and dive at depth (60+m for example). Deep enough for your decompression obligation to make it worthwhile staying down there and working rather than spending hours and hours (not to mention the risk) decompressing everyday. This involves living in a diving bell which is filled with a mixture of gasses; usually Oxygen, Nitrogen and Helium (squeaky voices). You enter and exit the bell to perform your underwater tasks. Sat divers don't use SCUBA, they are supplied breathing gas via umbilicals. 

During the time spent in the bell - which may be weeks - Helium, being a tiny element, can penetrate the watch.

Once you've finished your tasks the diving bell (and the divers within) is slowly brought back to atmospheric pressure according to a schedule tailored to the depth and time spent there- decompressed. During this process, the Helium, which has slowly leaked into the watch, is at higher pressure than the surrounding atmosphere. The helium release valve allows this pressure, which can pop the crystal, to be released. As DRMW wrote, this can be manual (per Omega) or automatic (per Panerai).

The alternative is to design the watch such that Helium cannot enter the watch in the first place. I know Seiko did this and I believe Omega did as well on the 600m PloProf.

As for maintenance: I haven't seen a cross section of a Panerai HRV, but basically, I understand it to be a spring-loaded one-way valve sealed with an o-ring. So it should require no more maintenance than the other o-rings and gaskets in the watch.

Hope this wasn't too long-winded.

B