WARNING - LDS rant enclosed

[Genesis]

Ok, this is just a rant, and the shop involved will remain nameless - its not intended to slam a business, just make a point about training and intelligence....

Did two dives today.

Took tanks to the LDS to have them filled so they'd be ready for my next dives.

I am Nitrox certified.

I wanted to have my tanks filled with EANx30, not the usual 32. The reason for this is that depending on the weather I may dive those tanks in 80' of water, or about 110-120', and with EANx32 my MOD is 111 for a PO2 of 1.4 - which is just too darn close for my taste. The 2% dilution doesn't cost me enough in NDL or surface interval time to be a problem for the shallower depths, but gives me a better safety margin on the deeper stuff.

I think this is perfectly reasonable. Don't YOU?

I need roughly a 6% dilution from EANx32, in other words.

Since the air in the bank is at 21%, and the EANx bank is 32% (nominally), what I want is a partial-pressure fill off both banks, first with the EANx32, then top it off with air.

Simple, right? I want a ppO2 of 900 psi, and a ppN2 of 2100 psi, since these are AL80s filled to 3000 psi.

So, to get that I can put in ~2600 psi of EANx32, and then top to 3000 psi with Air (21% O2), which produces...

2600 *.32 = 832 ppO2 + 400 * .21 = 84 ppO2 or darn close (30.5%) (I did the math in my head while standing behind the shop - I knew it wasn't exact, but it would be close enough.)

The tank guy refused, saying that he was going to do a partial-pressure O2 mix and I had to leave the tanks for him to do it (in other words, mix raw from o2 and air) or I had to take his banked 32%!

Now here's the kicker - THE VALVES ARE NOT O2 SERVICE RATED ON THOSE TANKS! They're O2 clean for a banked or continuous mix fill to 40%, but NOT for pure O2.

I got into it with the tank guy and subsequently the owner of the shop, as you might expect, and refused to allow the tank guy to do what he was intending to do.

The SHOP OWNER refused to do the fill as well, and again asked me to leave the tanks overnight for a "custom" fill. I again asked how that was intended to be done, SINCE THE VALVES AND TANKS ARE NOT O2 SERVICE RATED, and all I got back was "I'll take care of it."

Oh? How's that? Did they intend to do EXACTLY as I asked IN THE FIRST PLACE, but "silently"? Or were they intending to do a partial-pressure fill by bleeding down the tanks, then putting in pure O2 ANYWAY, even knowing the tanks weren't rated for it?

If the second, no thanks.

If the first, why not do it while I'm sitting RIGHT THERE?! What's the difference? It takes NO extra time to do it this way. Why not pull the tank guy aside, simply tell him to do what I asked and that you'll explain why its ok later if he doesn't understand, and handle it that way?

What the devil are these people doing in this business? What I was asking for was not a black art, nor anything complicated. I wanted a mix that I knew was safe for the depths at which it might be used, I knew exactly how I wanted it done, I told him EXACTLY how to do it, and there was absolutely no risk to him to do EXACTLY as I asked. The shop in question banks BOTH EANx-32 and air off the SAME compressor and fills off the SAME whips (just a different source valve), so there is no issue there. Further, at this shop you have to SIGN FOR YOUR MIX individually, so there would be NO QUESTION what I walked out of there with in the tanks - they're both labelled AND I witness the analysis.

How do you get a job filling tanks for people if (1) you won't listen to your customers, (2) you don't understand what you're doing, and (3) if what they're asking for does not violate any safety rules or in any other way hurt you (in fact it helps, since they "save" far-more-expensive Oxygen giving me a short fill on the Nitrox and topping it with air) do people get hissy about this kind of thing?

The REAL mind-bender? I asked the shop owner the following:

Let's say I go get my own bulk aviators O2 tank and do a partial pressure fill with pure O2. I then bring it to you and ask you to top it with air, making you fully aware that there is O2 in there now. Will you do it?

I was asked if I knew what had to be done to clean the tank and valve, and if I was capable of it. I said "yep", and explained. The subsequent answer was yes.

Now how does THAT make sense? They'll top a tank they KNOW has O2 in it with air for a custom mix, but they won't partial-fill off their OWN BANKS?!

That makes ABSOLUTELY no sense.

Maybe I need to invest in a compressor and transfill whip with a precision gauge, get set up to rent a couple of aviators bulk O2 tanks for a cascade and just forget about this nonsense. At the price I pay for Nitrox fills it will pay for itself in a few hundred tanks; if I go in with a few other dive buddies on this it would even be cost effective, not to mention saving me the drive over to the LDS....

(I warned you this was a rant!)

 

[Scubaroo]

Hmm, sorry you had problems getting a fill. My LDS banks EAN36 and hydrocarbon-free air, and has no problems with blowing air on the top to make them EAN32. On the spot. My tank is also not O2 clean, just nitrox clean.

Got another LDS you can try?

 

[Genesis]

has hydrocarbon-free air as well - they use the same compressor to fill both their Nitrox-32 and air banks.

 

[Spectre]

If you have 21% in the tanks now, bleed 'em down to 545 psi and tell 'em it's 32%. Have them fill it with the 32% bank and you're as good as gold.

I must say I'm happy I have the LDS I have. At my 'nitrox shop' they messed up and gave me 32% instead of 30% [and it analysed out to close to 33%... not good for a wreck in 120 fsw].

I took it to my home shop [who does PP fills], and he went over the 'fix' numbers with me, the re-analysis, and let me bleed 'em there and top 'em off... for free.

I'd personally be in the market for a new shop if they don't know how to [or listen to your math on] tweak mixes.

 

[sheck33]

of people filling tanks in the various shops get lost the moment you want anything other than 32 or 36 %. The last four nitrox fills i got where off by 1 to 2% from what i wanted. Not to mention i have seen the guys try to fill my doubles attaching 2 fillwhips, hello

 

[Uncle Pug]

Genesis once bubbled...
Let's say I go get my own bulk aviators O2 tank and do a partial pressure fill with pure O2. I then bring it to you and ask you to top it with air, making you fully aware that there is O2 in there now. Will you do it?

I was asked if I knew what had to be done to clean the tank and valve, and if I was capable of it. I said "yep", and explained. The subsequent answer was yes.

You don't need a compressor with a great shop like this!!!

Are you a knucklehead??? Sorry, that wasn't kind.
Are you stewpid or something??? Oooops, that wasn't any better.

Look Genesis... you have got a great deal here... if I had a shop with good air tell me "yes" to air tops I would have been all over it instead of putting thousands into a fill station!

I sure wouldn't be on the internet slappin them around!

Set up your gas banks and do your PP primes and let them blow air on top... you will even be able to do trimix for pete sake!!!

What a lucky deal....

You didn't burn any bridges at the LDS did you... no name calling or anything like that???

 

[Genesis]

Look, this is an ALGEBRA problem.

I can even give them a FORMULA to plug vaues into. I was able to do a rough calculation (close enough for what I wanted to do in this case) IN MY HEAD!

If I'm going to go to the trouble to put in a partial mix, then I'll go the rest of the way.

No, I didn't burn bridges. But I did lose a lot of respect today for a business that up until that point had gained a great deal of same, because a very simple, safe and reasonable request - and one that would take no real effort on their part - was flatly refused - and the offered alternative was clearly dangerous.

 

[Uncle Pug]

No big deal blowing in the air... as long as you get the final pressure you requested.

But if you want to go the compressor route....

Then you need to consider continuous blending rather that PP mixing... how sweet it is.

Got lotsa moolah?

 

[MikeFerrara]

No No No

They are abviously stupid and expensive to boot. Set up your own fill station and be done with it. Look you can get gear cheap on the net, pump your own gas and get parts to do your own service. What do you need them for?

I don't know about your shop but mine is in the dark ages. We only bank air but I will blend anything you want. I will even top your home brew (if I trust you not to blow me up). Hell, I'll do it even if I don't trust you cause if you got away with putting in the O2 I'll put in the air. When I am done my mixes will analyze to your satisfaction. Now the bad news, I may not be able to do it while you wait. You can wine. You can complain. You can call my mother names. But...if I decide I have too much going on to be able to blend, I'm not blending (we have a really small staff).

I also don't try to take care of customers while I rebuild regulators. I don't talk on the phone and visual tanks.

Were you late for a dive? Were you unaware of their polocies? It is true that some will adopt polocies that are counter productive, habit you know. Do you live really far away? If so did you try to make arrangements ahead of time? Or...did you just prance in insisting that they do this that and the other?

 

[Genesis]

ain't THAT expensive. I can BUILD a continuous blender, along with a solenoid-driven shut-off for the O2 in the event that it runs away (e.g. the compressor shuts down on me and the O2 is flowing).

Heck, I could pretty easily build a microprocessor-controlled CLOSED CIRCUIT system that would analyze the incoming mix to the compressor and adjust the FO2 as necessary - and automatically.

It ain't that hard, and my background is in computer and electronic engineering. This kind of thing is a trivial exercise for me. I already built my own O2 analyzer for personal use and verification on my Nitrox tanks...

The compressor is the big cost item.

But, if you have a few buddies to go in on it, the cost per user comes way down, and if you blow enough bottles, the math works - especially for Nitrox which is a HUGE profit center for the LDS.

The O2 (in volume) that goes in an AL80 Nitrox-32 tank costs under a buck when bought in an aviators O2 bottle (bulk). Yet the LDS charges four times that "uptick" on their banked Nitrox, which is quite the mark-up....

If you dive air the equation is more dubious since the filters for the compressor are relatively expensive, all told (and must be replaced on schedule or you end up with air that has hydrocarbons in it - not good!)

But if you dive EANx then the picture changes, especially if you and a few buddies dive often.

Also, the VIP thing (and its attendant costs) go away. You still need Hydros if you intend to transport the tanks (and you should have them anyway) but the entire VIP thing is a dive-shop-ism and has no bearing on legality anywhere in the US.

As for the shop in question, I would expect that if I needed something special that required a partial-pressure O2 fill that they'd make me schedule it. That's REASONABLE, since someone has to pay CLOSE attention during the process.

But that's not what I wanted here. All I wanted them to do is fill the tank to 2600 psi with EANx32, then top it off to 3000 with air. Their manifold has two valves (ok, three if you count the Haskel) - this would have been, quite literally, a 30 second deal and not extend the fill time in any measurable way. I also had 4 tanks to do, which happens to be only two less than their capacity at a given time (they have 6 whips), and I wanted all four done the same way - and at once.

It simply wasn't a major request, or one that took any thought. I didn't ask them to make the computation - just put it in by the numbers I gave them. I even explained that if the mix was off it was my problem - I'd sign for the tanks and their contents regardless (I wasn't after an EXACT number, just a rational cut-down of a couple of percent from the "usual")

This is also not a "new" shop for me - in fact, its one that I have EXCLUSIVELY patronized up until now for fills and such. Its not like they don't know me in there - I'm in there for one thing or another (often fills) a few times a week!

The problem for me is that as the weather cools this is going to be a more frequent requirement. The fish I want to hunt come into a particular area when the water starts to cool, and that area is the precise one that causes me trouble with MODs on a standard EANx32 fill. I want the benefits of Nitrox for it, but don't want to risk an CNS O2 hit, especially since I'm often going to be hunting and as such my exertion level may be higher than normal "sightseeing",

In some cases having to wait 24 hours may mean not diving on a given day. These sites are out there; you only go when the weather is right....

That leaves me with the options of (1) putting together my own fill station, (2) taking the risk of a CNS O2 hit and accepting their "standard" nitrox fill (clearly not acceptable), (3) finding someone who understands that this kind of request is neither difficult nor does it extend the time and effort required to fill the tanks or (4) deal with not diving as often as I'd like.