Size and system details of compressed air that I wish to select during development is a difficult decision to make. Cylinder size and volume are linked, and so any efforts to keep the device compact must recognise this.
I have chose to continue developing a solution that can take two sizes of cylinder. This is for the following reasons:
- The solution is to be aimed at children and adults of all ages and abilities. One size of cyinder does not account for all of these user’s needs.
- The ability to swap out one size of cyclinder for another larger or smaller one may make the solutuion more adaptable to a wider range of watersports applicatiuons.
Given that the rates of air consumption are as follows:
A half litre tank pressurised to 200bar means you have around 75litres of air to breathe before you hit 50bar. Air consumption is difficult to measure but the average tidal volume (the bit we breathe in an out during a normal breath cycle) of the human lung is 0.5l, and the average breathing rate of an adult is 12-20 cycles per minute, and so in theory, it would be possible to breathe from these devices for 12.5 minutes.
But those figures only apply to healthy adults at rest. The added exertion of swimming alone could easily reduce that figure by half. Taking breaths of 1.5 litres, 20 times per minute, would mean red-lining in 2.5 minutes – at the surface. At 10m, this translates to 1 minute and 15 seconds of air before reaching 50 bar – or 1minute 40 seconds before emptying the tank dry. At the ‘maximum’ depths of 50m or 20m, the air supply is reduced to mere seconds.
I will pursue development along two tank sizes:
Small: 0.25 litres – at 3000psi this will account for approximately 3 minutes for an adult at rest.
Large: 0.4 litres – at 3000psi this will account for approximately 6 minutes for an adult at rest.
Paintball:
Advantages over SCUBA:
- in-line threaded connection ensures compact, conventient mounting to any frame
- come in a variety of small sizes, can be either fibreglass reinforced steel or pure steel.
- include a pressure guage and seperate air filling valve adjascent to mounting thread.
Air & Water 