Nitrox cylinder bands

[Storker]

As for tank wrappers, as an individual owner of personal tanks, whatever you want. As long as you have something to show for that the tank/valve has been cleaned for Nitrox or O2 and a current analysis of what is in the tank(s).

Since I don't fill nitrox with PP blending, I really don't care. Inline mixing up to 40% puts exactly the same demands on your tank & valve as an air fill does, so "oxygen clean" isn't an issue for me personally.

However, I really, really don't understand why LDSs accept outside tanks with a three-quarter-year-old "Nitrox" sticker (except revenue). The risk is for the poor sucker who's filling the tank, not the guy who picks it up. I don't think I'd feel particularly comfortable PP filling an out-of-shop tank with an old nitrox/"oxygen clean" sticker; who the heck knows what kind of air has gone into that tank during the last months?

 

[Peter69_56]

Sorry if this has been mentioned before..

Nitrox cleaned and O2 cleaned are two different things.

For some shops they could be the same, but generally 'Nitrox ready/clean/compatible' are up to (MAX) 40% O2 content

They might not use O2 compatible lube, o rings or check thoroughly while cleaning valves.... So NO PP blending!

**this now has become a check with me when I get my tanks inspected, I drain them, crack off the valve and inspect the tank quickly and the I ring, then get it filled .... Had a few shops "O2 clean" tanks that had surface rust and wrong O rings when I pulled then apart to change out valves on the first fill**


As for tank wrappers, as an individual owner of personal tanks, whatever you want. As long as you have something to show for that the tank/valve has been cleaned for Nitrox or O2 and a current analysis of what is in the tank(s).

As for a commercial operation with a 'fleet' of tanks for rent/charter, then some sort of marking system should be in place (painted or wrapped tanks).

Same thing with dive boats where tanks are provided (ie Caribbean). No one might know if anything other than air is in a clean AL80, but that one that is a different colour, or has a band on it, might contain something other than Air (including He).

Joe Random isn't going to be renting your personal tanks, so there is little worry about what kind of marker to show what is in them (to Joe Random), but if you provide a service of renting tanks with Air, Nitrox and He, you better well have a system in place, otherwise no one would know what is what with no markings (staff and customers).


My tanks have up to 4 stickers/markings on them (only deco bottles with MOD)

1 - Vis sticker with o2 clean on bottom/inside (doubles)
2 - My initials (lower outside)
3 - MOD (21m, 6m) (higher outside)
4 - Daily analysis tape (neck)

And for sake of thoroughness, my drysuit inflate has a warning sticker (and Vis) saying that there is most likely anything but air inside the AL6, and you will die if you try to breath it.


BRad

The cost for either is about the same. Effort is about the same. On that basis alone I would only ever ask for Oxygen clean. Then should I find that the LDS has used incorrect O rings etc, I would then take them to task.

That I clean my own means I am assured of the job done.

 

[bradells]

Since I don't fill nitrox with PP blending, I really don't care. Inline mixing up to 40% puts exactly the same demands on your tank & valve as an air fill does, so "oxygen clean" isn't an issue for me personally.

However, I really, really don't understand why LDSs accept outside tanks with a three-quarter-year-old "Nitrox" sticker (except revenue). The risk is for the poor sucker who's filling the tank, not the guy who picks it up. I don't think I'd feel particularly comfortable PP filling an out-of-shop tank with an old nitrox/"oxygen clean" sticker; who the heck knows what kind of air has gone into that tank during the last months?

So, do you think fill stations should require a tank to get an O2 cleaning (tank and valve) every time you get a fill then? What is your thoughts on 'how old is too old?' - # fills/time?

BRad

 

[tbone1004]

Can't wait for the specifics.

buy the oxyhacker and find the DIY blend stick. It's not that bad. Even still, we'll go with the expensive Amigos version at $3200 which does auto blending of trimix and oxygen, same way a rebreather works. T bottle holds 337cf of gas at 2640psi. You can't get a really useful mix any lower than 400psi, and if you pp blend lower than that it's just inefficient. You leave 50cf of gas left in the cylinder at 400psi. Amigos is currently charging $0.40/cf so let's assume it's half that for markup. $0.2*50=$10 in wasted gas per cylinder. At $3400 for the official stick *which includes sensors, the solenoids, the software, and two regulators for He and O2 bottles*, you have to go through 350 bottles of O2 which is a lot, but you can build one for about $300 including the O2 analyzer. That pays for itself in 30 bottles of O2 alone, but more importantly, it saves you having to PP blend, which is just annoying, PLUS you have to factor the cost of the actual gas that you have to dump every time you PP blend at low pressures. Sure it's probably only costing $0.05/cf, but if you have divers coming back with 1000psi in an 80, you have to put $1.50 per tank of extra gas back in there, and that adds up over time.

The nitrox stick from Amigos allows you to tell it your current bank pressure and percentage and your final percentage and pressure and it does all the mixing for you for custom mixes. What is your time worth?

 

[boulderjohn]

At $3400 for the official stick *which includes sensors, the solenoids, the software, and two regulators for He and O2 bottles*, you have to go through 350 bottles of O2 which is a lot, but you can build one for about $300 including the O2 analyzer. That pays for itself in 30 bottles of O2 alone,

In my area, it would take a typical shop 5 years to go through 30 O2 bottles.

 

[tbone1004]

i was using a worst case scenario, so we'll go from 30 T bottles to a more realistic number

Now, a single T-bottle will fill 39 AL80's with 32%. By using a stick instead of PP blending, you save about $1.50 fill due to a combo of the wasted gas when draining and the saved O2. $300/$1.50=200 fills of AL80's, or 5 T bottles, which is a 1 year ROI based on the usage you quoted. Now that was with a dedicated analyzer, which you don't have to have, so you can actually reduce the cost to like $100 without the analyzer because all a blending stick is, is a PVC pipe with some whiffle golf balls in it, a needle valve at the top, and a sensor at the bottom.

This is again, not including any added costs of having to maintain O2 clean fill whips, which is time and money every year to clean them, the extra cost and expense of making sure that all of your equipment is O2 clean to ensure that you have clean air going into the cylinders, the added expense and hassle to your customers of having to O2 clean stuff, which while coming in at a lot of business for the shop, is really annoying as a customer, especially if you are travelling through the area.

 

[Storker]

So, do you think fill stations should require a tank to get an O2 cleaning (tank and valve) every time you get a fill then?

Nice strawman there.
No, of course I don't. I'm just saying I wouldn't feel particularly comfortable blowing pressurized pure O2 into a tank with an old nitrox sticker and no traceability as to what has been put into it the last XX months. What fill stations should or should not do isn't up to me to decide.

 

[markmud]

My LDS banks 50% nitrox. So, they require O2 clean tanks. I can go 3 miles down the street and get a stick-blend up to 40% without O2 clean tanks. Saves me $50.

After I return from a SoCal dive trip, I tell my LDS that my 02 clean tank was filled with a Nuvair system that feeds a standard compressor. They don't seem to care. I guess they are sure that the compressors used on the dive boats I dive from produce a very high grade of air...dunn-know...

markm

 

[Peter69_56]

My LDS banks 50% nitrox. So, they require O2 clean tanks. I can go 3 miles down the street and get a stick-blend up to 40% without O2 clean tanks. Saves me $50.

After I return from a SoCal dive trip, I tell my LDS that my 02 clean tank was filled with a Nuvair system that feeds a standard compressor. They don't seem to care. I guess they are sure that the compressors used on the dive boats I dive from produce a very high grade of air...dunn-know...

markm

Or perhaps they live in ignorance

 

[markmud]

Or perhaps they live in ignorance

Hi Peter,

You made a general statement; how about some specificity?

They are definitely not ignorant. They bank 50% to make it easy to fill 50% deco bottles (at the expense of rec divers). I am in a Tec 40 class and will not use 50% on a normalized basis. I don't know how many deco bottles they fill; it may be a huge business.

So, they are ignorant because:

1. they bank 50%?
2. they make people get O2 cleaning for 50% PP blending?
3. they fill tanks with 50%, tanks that may have been contaminated?
4. they know customers are driving to a different LDS for EANx and are making personal connections with the competition?

As far as tank bands, I use bands when it makes sense for me. I have a pony bottle that I load with 40% and it has a band. My O2 clean tanks have bands. The bands on the other tanks are useless except to promote rust on my beautiful PST 100 E7 tanks.

thanks,
markm