Diving Sums

Nowadays calculations are done by computers, laptops & phones. I know when I did my course the sums behind technical diving (both OC and CCR) was broadly glossed over. For example when I did my CCR course I remember that the equations were shown but mostly just to make the point that a fixed PO2 rather than a fixed FO2 is the main difference between OC and CCR diving.

Thinking back to the OC course we did a few more sums as we needed to figure out what gas to use and from what depth it would be OK. On the blender course we did a few calculations, but mostly we used a look-up-table or a software program.

There are a few other calculations which I've found useful over the years and I'm planning to round them up here in a series of short posts. Here's the list I have ready to go - and I may add more later:

- Gas Selection
- Isobaric Counter Diffusion
- Gas Density
- What gas am I breathing?
- Cylinder Filling for Trimix

I'm a practitioner and not a theorist so some of the formulas are not conventionally formatted – they are intended to be used not studied and therefore are formatted a bit more practically. Also I'm a CCR diver so they all have a CCR slant - but they work the same for OC too.

A note of caution – these calculations are metric. Imperial diving units are just crazy! Also I do not always use depth in meters I sometimes use depth in bar – whatever makes sense in the context of the calculation – here is what I mean:

I'm not an instructor and there maybe mistakes. If anyone finds one then I'll correct it. There's other ways to arrive at the same answer - I find that although owning and using a computer, laptop and phone is the way I do most things a little bit of theory never hurt and some people might find this useful.

If you don't like sums don't read on :-)

Matt.