mwilding
Contributor
I am about to take my intro to tech class. I have a set of small steel 72's I am going to be learning on. I have just been reading about using an HP120 (or similar) to top off the doubles after a dive and am wondering about the math of it all.
Assuming a straight fill at 2250PSI, I would have 2X 65cu ft or 130cuft of gas for my first dive.
I have a nice dive and return to the surface with 1125PSI. This is a reasonable expectation for me as I have come up with similar PSIs when diving 120 singles. It is also similar to the amount of gas I would use diving a single AL80 if I surface with >= 500PSI left in the tank.
So, at this point I would hook up the transfill whip and move gas from the HP120 to the 72's. Now how much gas do I have in my doubles?
If I had an HP130, the math is easy (i think): (3300PSI + 1150PSI) / 2 = 2225 almost a full tank. Is this right?
OK, so now for the 120. intuitively, the pressure will be lower, but I can't quite get the conversion without over complicating it.
The bottom line for me is, once I am ready, I can start making boat dives in my doubles and taking along an HP single and a whip would be easier that buying or renting another set of doubles. Am I missing anything here?
Assuming a straight fill at 2250PSI, I would have 2X 65cu ft or 130cuft of gas for my first dive.
I have a nice dive and return to the surface with 1125PSI. This is a reasonable expectation for me as I have come up with similar PSIs when diving 120 singles. It is also similar to the amount of gas I would use diving a single AL80 if I surface with >= 500PSI left in the tank.
So, at this point I would hook up the transfill whip and move gas from the HP120 to the 72's. Now how much gas do I have in my doubles?
If I had an HP130, the math is easy (i think): (3300PSI + 1150PSI) / 2 = 2225 almost a full tank. Is this right?
OK, so now for the 120. intuitively, the pressure will be lower, but I can't quite get the conversion without over complicating it.
The bottom line for me is, once I am ready, I can start making boat dives in my doubles and taking along an HP single and a whip would be easier that buying or renting another set of doubles. Am I missing anything here?