At the time of building the instrument we can use any one of the following options for the depth channel:

For the plastic case select from the following ranges (all in metres of water)

0 to 20, 50,100, 200, 500, or 740 metres

And for the titanium case, select from

0 to 1000, 2000, 4000, 6000 or 10,000 metres

These are all nominal ranges.  The choice depends on the application.  If the instrument is only going to be used in shallow water, it would make sense to use the lower ranges.  If on the other hand it needs to go to greater depth then a gauge is needed which has sufficient rating otherwise the gauge will be damaged.

The reason for having to make a choice is that the accuracy of measurement is 0.05% of the full scale reading.

Hence, if you have a full scale of 740m the accuracy is 0.05*740/100 or 0.37m.

For the 20m range, the accuracy is 20*0.05/100, or 0.01m.  About 10 mm.    Quite a difference!  But as the next table shows, the 20 m gauge cannot be used beyond 40m.

The selection is complicated by another factor:  each range has a maximum beyond which it should not be used  This is called the “proof pressure”:

Range up to (m)          Absolute Max (m)

20                                 40

50                                 70

100                               150

200                               300

500                               740

740                               740 (limited by the case)

1000                             2000

2000                             3000

4000                             6000

6000                            9000

10000                           11000

When we configure an instrument we try to select a gauge which will give the best compromise between highest accuracy and being able to operate over the full range intended.

Special case.

RBR can also supply a DR-1050P with a 10dBar sensor.  This is to measure atmospheric pressure only.