Posted by tecdiver on September 13, 2002 at 13:50:10:
In Reply to: Pony Tanks posted by Slim on September 13, 2002 at 12:27:05:
There is no pat answer to that. There are factors you need to consider. How many cf/m would you breathe off the cylinder at that many ata of pressure. Would you be penetrating the wreck? A pony can range from 6 to 20 cf and there are buoyancy considerations. If you needed to abort the dive due to a problem with your primary gas, could you ascend safely, meaning within a safe rate and do at least a 2 min stop at 10-15 ft.
A rough answer would be 13cf, you also need to remember, if you need to breathe that cylinder in an emergency what will your breathing rate be then.