Question So what is this?

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JohnN

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This was on a display mannequin in Willemstad Curaçao

1674341666439.jpeg
 
It’s a depth gauge. One of those things used before computers.

It has a maximum depth indicator. The red needle and screw used to reset it.

It goes round more than once for depths deeper than 25m.

Don't know what tables the no stop times are from? US Navy?

And it’s metric.

It says Italy, so a guess it was manufactured there.
 
The dial indicates minutes along with depth. I'm thinking it's an early decompression-meter.
 
The no deco limits look like a match for US Navy air tables assuming no residual nitrogen. The minutes remaining would not apply to repetitive dives.
 
It's a capillary depth gauge, old style. Max depth needle and no decomp table included. Extreme vintage.
 
It's a capillary depth gauge, old style. Max depth and no decomp included. Extreme vintage.
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

il_570xN.4477298641_phku.jpg
 
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

il_570xN.4477298641_phku.jpg
You are right, of course. I mixed the two old things up. Defective memory.
 
The markings get closer together on this gauge too....first circuit is 0-25m, second is 25 to approx 85m.

Yes, as @Kupu said, the NDL limits are exactly those of the USN (old) tables: 15m/100min, 18m/60min, 21m/50min, 24m/40min.

1674350258115.jpeg
 
The markings get closer together on this gauge too....first circuit is 0-25m, second is 25 to approx 85m.
You are correct, I missed that. But it's not nearly as dramatic an increase as with the capillary gauge. The formula for any depth marking in bar (approximately 10m) on a capillary gauge (starting at infinite depth) is 1/bar absolute. So 10m is 1/2 the length, 20m is 1/3, 30 is 1/4, 40 is 1/5, etc.
 

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