New Tank Questions

[halocline]

I would fill it with 40% and switch to it for use during my ascent and safety stop to increase the rate of off-gassing nitrogen. I mentioned 40% assuming that his EAN cert limits the OP to 40%, otherwise 50% would be better.

This would be a very bad idea for a bailout bottle, which is what a pony is. You may need it at well past the MOD for a higher O2 percentage blend.

Carrying a 30cft bailout bottle on single tank recreational dives is a bit of overkill, but to each his own. Already the OP is thinking about using this bottle to somehow extend his dives. This is exactly why pony use is controversial.

If you dive safely, meaning with good buddy skills and careful gas monitoring/dive planning, a bailout bottle is IMO a convenience allowing you to have a more leisurely trip to the surface in the event of reg/tank failure for you or your buddy.

 

[Tigerman]

...
If you dive safely, meaning with good buddy skills and careful gas monitoring/dive planning, a bailout bottle is IMO a convenience allowing you to have a more leisurely trip to the surface in the event of reg/tank failure for you or your buddy.

When I had to share air with my buddy last summer in the red sea, it was actually very leisurely even without a pony. I rarely drop below .5 cu/ft minute consumption and at that dive I was at .48 with two people breathing off my tank for half the dive
(The dive was short and her air was going away so fast you could SEE the needle drop on her spg, due to a tank valve o-ring blowing after about 5-6 minutes - full story should be in my sig).

 

[halocline]

Thanks all for the responses. Sounds like I should just take the tank and valve in and have them do the inspect/fill before I do my next dive.

I'm leaning toward trying to synch the pony with whatever mix I'm diving. If I have a primary regulator malfunction, then I'm done for the day anyway. If for some reason I need to go to the pony but my gear is working, then I haven't screwed up my computer/tables. I spearfish, and stuff happens.

If there is no current VIS sticker on the pony, you will need the inspection to get it filled, unless you can transfill it yourself from another tank. (That's what I do) If there's a current sticker, just put the valve back on. Use a new o-ring and lightly coat the threads on the valve with either silicone or an O2 safe lube. Don't lube the o-ring.

If your primary mix is filled by partial pressure, you'll need to O2 clean the pony to get that as well. I would just use air. I don't think it matters much from a deco perspective; you're using the thing to get to the safety stop and out.

Sometimes tank o-rings blow, and you will use your pony and still want to dive. Or you reg might be easily fixed during the surface interval by replacing a hose o-ring. I would not assume that once you've used the pony, you're done for the day.

You should really think through the statement "I spearfish, and stuff happens." What exactly is "stuff"? Unplanned deco? Failure to look at your SPG because you're chasing a fish? I'm not trying to get on your case, but you said in an earlier post that you consider yourself a conservative, safe dive, but to me this statement does not mesh with that.

A pony, IMO, is a redundant air source in case of gear failure at a point in the dive in which your buddy does not have enough gas to get you both conveniently and slowly to the surface. It is not, IMO, a bottle to cover you in case you decide to stray from your buddy. That's solo diving, and although a bailout bottle is part of solo diving, there are lots of other things too.

Have fun, sounds like you're trying to dive safely. IMO that's more about behavior than any type of gear choice.

 

[halocline]

When I had to share air with my buddy last summer in the red sea, it was actually very leisurely even without a pony. I rarely drop below .5 cu/ft minute consumption and at that dive I was at .48 with two people breathing off my tank for half the dive
(The dive was short and her air was going away so fast you could SEE the needle drop on her spg, due to a tank valve o-ring blowing after about 5-6 minutes - full story should be in my sig).

Good for you. Others might not have as good air consumption and/or be in a different position in the dive. The occasional pony use that I've done has been on a liveaboard where the dives are deep and square; 5/day. If something happened late in the last dive of the day, I'd want to make sure I was able to take as long a stop as I wanted.

 

[Tigerman]

Good for you. Others might not have as good air consumption and/or be in a different position in the dive. The occasional pony use that I've done has been on a liveaboard where the dives are deep and square; 5/day. If something happened late in the last dive of the day, I'd want to make sure I was able to take as long a stop as I wanted.

As I said, my air consumption normally isnt that good (hes was tho, since she was a small woman) and obviously how much gas and other issues arrise would depend on how both the divers needing to do the airshare responds to the situation. In the case I was referring to both the divers where calm and dealt with the situation quick and easy and importantly where close to eachother so that the issue didnt get to escalate.
And yeah, my previous comment WAS made tounge-in-cheek if you didnt catch it..

 

[Doc Harry]

Screw the valve on hand-tight to prevent contamination of the tank until you get the inspection.

Catalina recommends that valves on their cylinders be torqued to 40-50 foot-pounds.

For torque reference, go to:
Catalina > Tech Support > SCUBA Cylinder Market > Valving of SCUBA (Air) Cylinders

Personally, I would put air in my pony if the pony is to be used for emergencies. The MOD of air is always going to be deeper than the MOD of any Nitrox in your back gas.

If you are using a pony to extend bottom time, then I'd just get a bigger cylinder for back gas. I guess that if your pony is to extend bottom time, then it has to be the same mix as your back gas, or you have to remember to switch gasses on your computer.

 

[ams511]

What happens when your main tank is almost empty,you switch to the pony at 130 feet , and find it does not work for whatever reason?

You NEVER want to be in the position of your life depending on a single piece of gear working as expected.

I don't understand your point. The OP said he has poor air consumption not poor gas management skills. This post is not in a solo diving forum so I would assume the OP would have a buddy. Also how would a malfunctioning pony bottle be any different than having no pony at all? Also who said the OP dives to 130 feet?

 

[halocline]

Catalina recommends that valves on their cylinders be torqued to 40-50 foot-pounds.

I can't imagine ever tightening a valve to 50 ft lbs. Why so tight I wonder? With any air pressure at all it's not going anywhere.

 

[Jax]

I have all my own gear except tanks, which I've always rented. To help with my own safety, I just purchased a pony setup. I have a standard regulator with the small pressure gauge screwed into the first stage. I also picked up a 30cf Catalina tank with a Genesis valve. The tank came in a plastic bag and the valve came in a separate package. Here are my questions:

Do I go ahead and screw in the valve, or leave it off because someone needs to do a visual inspection?

If I do install the valve, is there some specification for torque?

I almost exclusively dive Nitrox (and I always dive the same mix for each dive on a given day -- eliminates one opportunity for me to screw up by not resetting mix on my computer between dives). Should I also have the same Nitrox mix in the pony tank?

One more question, this one will probably get me yelled at. 30cf is a decent amount of air. Given the best I usually find on rentals is AL100's, I'll now be able to carry 30% more gas. I'm a big-time air-sucker and blow through an AL100 well before I run out of bottom time (I'm working on that). Is it a mortal sin to use the pony to extend my bottom time?

Thanks!

Consider yourself yelled at!

 

[joe8mofo]

This would be a very bad idea for a bailout bottle, which is what a pony is. You may need it at well past the MOD for a higher O2 percentage blend.

IMHO it is not a bad idea; what is the point of carrying a pony bottle with no intention of actually using it. Even if the OP looses a reg at 130' and switches to 40% O2 at depth, he will BRIEFLY be exposed to a ppo of 1.98 and in 30 seconds to 1 minute will be at Contingency depth (1.6 ppo which some treat as MOD), within 16 more seconds he will be at MOD. Oxtox doesn't magically happen when you exceed the recommended PPO; it happens when you remain at a high ppo for a length of time; it is a cumulative affect. So anyone hitting a ppo range of 1.98 to 1.6 for 30 seconds to a minute is not considered at a substantially higher risk. If a reg fails you start your ascent, and in this case the OP has enough gas to make it to the surface; if the reg doesn't fail then the OP gets to use the PONY on ascent from a depth within MOD with the added safety factor of an decreased pressure of nitrogen in the breathing mix and therefore more offgassing on ascent and safety stop.