Question So what is this?
- Thread starter JohnN
- Start date
Please register or login
Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.
Benefits of registering include
- Ability to post and comment on topics and discussions.
- A Free photo gallery to share your dive photos with the world.
- You can make this box go away
I and my wife owned two, identical. Diaphragm-type depth meter with polycarbonate body and filled with air, manufactured by Mega Sport, Torino, Italy and sold with various names (Mares, Scubapro, Cressi, Modulo M, etc.). My one is marked Modulo M, and it is still working perfectly, the one of my wife was flooded. Here some photos of my one:
After removing the back stainless-steel cover, the brass diaphragm acting on the internal mechanism is exposed (with some oxide, as you can see).
Pressing the diaphragm the depth indicator moves, as shown here:
At the time (ca 1980) this was possibly one of the best depth meters you could buy, as it is demonstrated by the fact that my one is still working perfectly, after 40 years and more than 1000 dives.
I always kept my one in a console together with a brass Scubapro pressure gauge, which is also still being used.
I replaced the depth meter with a Cressi Leonardo computer a couple of years ago, because I had to dive in a site where a DC was mandatory.
And yes, the NDL limits are to be evaluated against the orange "max depth" needle, according to US Navy tables (for a single dive per day, of course).
It must be noted that there were two versions, the one in the original message was the version with double scale (two turns of the needle), my one is the single scale.
It is not a bourdon tube, which is remarkably linear. This is a diaphragm meter, with a pseudo-logarithmic scale.
It is not a bourdon tube, which is remarkably linear. This is a diaphragm meter, with a pseudo-logarithmic scale.
undrwater
Contributor
Thanks! Your pics didn't make it through... At least on my side.
The learning never stops
Diaphragm depth gauges are still being made. For example:
Wrist Depth Gauge — XS Scuba - Everything For The Perfect Dive
Depth gauge 200 ft (60 m) maximum Air filled, steel diaphragm construction Maximum depth indicator needle Luminescent gauge face Rubber boot with wrist strap p/n GA450 (Imperial) GA450M (Metric)
www.xsscuba.com
They were links to Google Photos.
Now I reposted them properly, they should be visible.
There is no “colored water inside.” It is open and ambient water enters the tube. It has a colored area behind, which changes slightly with the water that enters. You can easily see the line which indicates the depth, which is shown by the numbers. If you’ll note, the 33 foot depth is half way around the capillary gauge, and 66 feet is 2/3s of the way around. Does that remind you of anything?It's a standard Bourdon tube gauge, not a capillary gauge. Capillary gauges do not use a needle, there's just a clear tube with a colored liquid inside, the end of the liquid indicates the depth. They are easy to spot, not just because of the lack of a needle, but because the depths indications get closer as you go deeper.
This is a capillary depth gauge
SeaRat
Lee Strickland
Registered
To be sure, it is only a depth gauge, not a decompression meter/computer. It does have no-decompression limits at various depths based on the US Navy dive tables and a square dive profile. It must be used in combination with a watch or bottom timer. Yes, it is a Bourdon Tube mechanism.
It is a diaphtagm mechanism, explaining the not-linear scale (more expanded at small depth).
Bourdon tube pressure meters are linear.
Lee Strickland
Registered
Sorry, I stand corrected.
Similar threads
