Dive shop expectations on "Tank Fills"

[peterbj7]

Pretty much every dive shop i know uses partial pressure blending

Is that in Dahab? Is it the same down in Sharm? When I was last in Dahab (10 years ago!) there was only one shop doing nitrox, and they did use PPB. I'm pretty sure the few in Sharm who did it also used PPB, but hey that's ages ago.

 

[deepstops]

I'm still a fan of filling your own tanks with 02 then topping off at the LDS. For less than a $300 investment, you avoid alot of hassle.

I know shops that don't sell nitrox at all and drain your tank before they will fill it just because of people doing this. If they don't sell nitrox, I also suspect their air isn't clean enough for nitrox anyway.

 

[NAM001]

Have you talked to him about the delay. I would tell him that if he could bank air, then he would be able to give you a nitrox fill in a couple of days and if he is unable to do that, then you'll have to rethink bringing your tanks to him. Don't be threating or argumenative, just let him know you aren't pleased.

I have a feeling that his setup is similar to some I've worked with. Compressor sitting in an unairconditioned area. The heat and humidity really makes them work hard for that top pressure.

at minimun suck air from an air conditioned space. really decreases the moisture separation problems.

 

[Brian Sharpe]

Hey guys...

I am trying to get a good feel when it comes to filling your tanks with nitrox at your LDS... If you ask for 32, do you get 32...?

lee

Hi Lee it certainly sounds like your LDS is dropping the ball or maybe I'm just spoiled - mine banks EAN32 and fills are done while you wait (90% of the time - sometimes I'll leave my tanks when there are quite a few ahead of me).

I hope the "if you ask for...." was a rhetorical question. You do analyze every tank every time don't you?

 

[peterbj7]

at minimun suck air from an air conditioned space. really decreases the moisture separation problems.

But too often it's impracticable. Down here in Belize that is what I intended to do, as it is extremely hot and humid, but I couldn't make it work. You need monstrous (and down here incredibly expensive) air conditioners to cope with 52cfm, and with the salt air and erratic power supply they rarely last more than a year. It's cheaper and infinitely easier to deal with the wear-and-tear on compressors and filters. Incidentally, a set of three filters for a Bauer top-of-the-range filtration system here lasts 3-4 weeks (6 absolute max) and costs over US$700. Compare that with prices and lives anywhere in the US.

 

[chazrich]

+/- 3%? I had to read that twice and decide whether or not you were kidding.

Sorry, but if I ask for 32% Nitrox then that is what I want. I went to a shop that analyzed the air when they brought the tank to me and pulled the analyzer away before it had settled down so that I wouldn't know that they hadn't gotten the mix exactly right. I pulled out my own analyzer once clear of the shop, tested it, and found it to be nearly 2% over. I paid for the gas and made a note of it, but haven't filled my tanks there since.

 

[peterbj7]

You do appreciate that it takes time - several hours - for the analysis reading to settle down? How long had the tank been filled when you took it away? And (despite what someone here seems to think) it is likely to change when the tank is moved. 2 %age points (which is not 2%) is well within the range a tank may change as it settles down.

The only way to get predictable nitrox fills is to use something like a membrane system and bank the nitrox. Anything else is makeshift and approximate.

 

[chazrich]

You do appreciate that it takes time - several hours - for the analysis reading to settle down? How long had the tank been filled when you took it away? And (despite what someone here seems to think) it is likely to change when the tank is moved. 2 %age points (which is not 2%) is well within the range a tank may change as it settles down.

Yes, I understand that, but you get to lie to me only once. If you analyze the gas and tell me the correct reading I'll deal with it and test it later. But pulling the analyzer away to avoid having to deal with even discussing the differences just screams dishonesty. Of course I'm used to normally getting banked gas, for which there is not as much discrepancy (if any).

 

[Buoyant1]

I'm freaking spoiled! I have two outlets for Nitrox in my general area, one is the LDS I got certified with, the other is a "private" shop run by two of the instructors that used to work there (Husband and wife) and besides instruction, they do fills. I get my cylinders filled while I wait, and most times get a cold beer! (of the microbew variety! )

Private shop also is set up for Trimix, and charges by your gas volume as opposed to $XX. per fill no matter what's left in it!! (case in point, had two 119's topped off for $15. and change the other day) Had I taken it to the other shop, I would have paid $12. (could be more now) per cylinder regardless that I had 1500 psi in one and 1100 psi in the other But I can get my fills while I wait there as well!

That said...the OP's shop sounds like it doesn't like to do any mixes...

I vote for finding a NEW SHOP!

 

[Tigerman]

You do appreciate that it takes time - several hours - for the analysis reading to settle down? How long had the tank been filled when you took it away? And (despite what someone here seems to think) it is likely to change when the tank is moved. 2 %age points (which is not 2%) is well within the range a tank may change as it settles down.

The only way to get predictable nitrox fills is to use something like a membrane system and bank the nitrox. Anything else is makeshift and approximate.

So youre saying that 35% is not 3% more than 32% and that 2% more oxygen in the mix is acceptable?
I would agree that 35 is not 3% more than 32 (thats actually 9,4%) but last i checked 35% means 35 parts of 100 and is 3 parts of 100 (3%) higher than 32 parts of 100..