LDS and Nitrox fills.

[kelemvor]

And if you pull into a gas station in New Jersey and tell the attendant to "fill 'er up", and he gives you 93 octane (assume a Sunoco station), will you get mad and say "I meant regular unleaded"?

And I am always asked what pressure I want my tires at. I would never go back to someplace that assumes that they know what I want. So, my opinion is right and yours is wrong. So neener neener neener.

According to the OP he asked for and didn't get 32%. It didn't sound like there was much room for a miscommunication.

 

[eelnoraa]

If you know your shop banks 32, and you ask for 32 in your tank, I would not expect them to measure what was there, I'd expect them to put 32 in my tank. If I specifically asked for an ending percentage of 32, that's a whole new ball of wax.

This I can accept espeically when I didn't tell them I have air in it from previous fill. However, for partial pressure fill, I think analysing the existing content and pressure before partial filling is necessary, and I think it is reasonable to expect the shop to do it.

 

[NAM001]

Service was ok, just the quirky interpretation of rules for that site.
For grins the sticker in the tank said 27 ro 28% and had a mod for 32 on it. Either way as others have said, communications, attention to detail, verification is the keys you need to have adn use.

I'm trying to think of parallels in other situations where you get something added to a container, such as gasoline in your car, drink in your cup, etc, but I'm not sure of a perfect analogy.

Did the shop refuse to drain and refill? I've drained and refilled tanks for customers before when they requested a very specific ending percentage that I missed by .7%.

But, when I shop, I always phrase it as "just throw some ____% on top" so it is clear that I know the ending percentage might be off by a bit based on what is in the tanks. If I need something else, I would work out what could be done with the banked mixes, or bring the tank in drained. I try to make the work of the fill monkey as easy as possible, because I've had my own fair share of odd experiences.

Was the service good other than the misunderstanding? If so, then it's just a matter of not saying "I want" and either saying "throw ____ on top" or "I need it to end up at ____". If not, then don't go back.

 

[Redshift]

So it sounds like the OP went into a shop that banked 32%, he asked for 32%, and the fill station operator put 32% on top of a partial air fill. The final analysis came up well short of that, but that's not really the fill station operator's fault... unless you told him otherwise, it wasn't a stretch for him to assume you had 32% in there already, or that you didn't care that you'd come up a little short on the 02 analysis.

What?!!

1 - They should not "assume", they can ask or analyze it. Just as divers don't assume a shop has blended a mix properly.
2 - They have to analyze it before delivering it to the customer and thus, notice it's wrong!

 

[Brandon]

This illustrates some of the reasons why we teach about the different mixing methods in nitrox courses, and why all agencies advocate contents labels with the analysis on all mixed gas cylinders. Safety issues aside, it helps avoid confusion on fills.

A mixed gas cylinder with air in it should have been marked 21.0%.

If the shop fills 32% from banked 32%, the OP's Slightrox fill would be the expected result. Only PP blending (or some other custom process) should leave you with the expectation of starting with 21% and ending with 32%.

The OP skipped the PP blending option and asked for the standard banked gas... And that's exactly what he got.

To use the gas station analogy more precisely... The OP asked the service station to fill him up with 93 octane, when he had a quarter tank of 87 octane, and was surprised to discover that meant he had something other than a full tank of 93 octane when they finished.

And we're blaming the gas station attendant?

I'm no fan of fill monkeys, and I throw dive shops under the bus every chance I get, but that just doesn't make sense...

 

[Redshift]

If the shop fills 32% from banked 32%, the OP's Slightrox fill would be the expected result. Only PP blending (or some other custom process) should leave you with the expectation of starting with 21% and ending with 32%.

The OP skipped the PP blending option and asked for the standard banked gas... And that's exactly what he got.

That's your assumption. What the OP said was

First it was broken down to size of tank, LP or HP then Air, 32% and then Custom Nitrox. I asked for 32% and they said sure NP.

He asked for EAN32, didn't tell them what to put in nor how to blend it. It was a new shop, the OP doesn't mention knowing they had banked EAN32.
It may have been miscommunication, but usually when one asks for a mix, is the final mix that should be in the tanks. We don't know the exact words used...

To use the gas station analogy more precisely... The OP asked the service station to fill him up with 93 octane, when he had a quarter tank of 87 octane, and was surprised to discover that meant he had something other than a full tank of 93 octane when they finished.

And we're blaming the gas station attendant?

In a gas station we ask what we want to be put in, not the end result. For a gas mix, usually what is asked for is the end result. The way a shop uses to obtain it depends on their system and preference. It doesn't matter, as long as the final mix is what was asked for. And the diver does not need to tell the shop how to get to that mix, they should know.

 

[Wookie]

It sounds (to me) like there would be a lot of communication gaps and a lot of unhappy folks in most dive shops.

 

[AfterDark]

I am with brando, it was not their fault, and it is also not traumatic, empty your tank before the next fill

That's it right there the solution!

I've got 2 tanks right now with a small amount of 21% in them. If I go for nitrox next fill, I'd empty them before I loaded them in my car for the trip to the LDS. Simple solutions to simple problems.

 

[boulderjohn]

This illustrates some of the reasons why we teach about the different mixing methods in nitrox courses, and why all agencies advocate contents labels with the analysis on all mixed gas cylinders. Safety issues aside, it helps avoid confusion on fills.

A mixed gas cylinder with air in it should have been marked 21.0%.

If the shop fills 32% from banked 32%, the OP's Slightrox fill would be the expected result. Only PP blending (or some other custom process) should leave you with the expectation of starting with 21% and ending with 32%.

The OP skipped the PP blending option and asked for the standard banked gas... And that's exactly what he got.

To use the gas station analogy more precisely... The OP asked the service station to fill him up with 93 octane, when he had a quarter tank of 87 octane, and was surprised to discover that meant he had something other than a full tank of 93 octane when they finished.

And we're blaming the gas station attendant?

I'm no fan of fill monkeys, and I throw dive shops under the bus every chance I get, but that just doesn't make sense...

According to the OP he asked for and didn't get 32%. It didn't sound like there was much room for a miscommunication.

What was actually said and intended may be different from what was understood by the staff.. Here is how the conversation might have gone:

"I would like to have 32% nitrox in this tank." (Intent: I want a final fill of 32%.)
"OK." (Understood: You want 32% added to what is in the tank.)

Here is how the conversation could have gone instead:

"I would like to have 32% nitrox in this tank." (Intent: I want a final fill of 32%.)
"Do you want a final fill of 32%, or do you want 32% added?"
"I want a final fill of 32%."
"Is there gas in it now?"
"Yes."
"Is it at 32% now?"
"No."
Do you want us to custom blend on top of that, or do you want us to drain it and fill it from our 32% bank? It will be a lot cheaper if we drain it and give you the banked gas."
"OK, do that."

If I were the owner of such a shop, my training process would make sure that the employees went through the extra steps required in the second conversation.

 

[String]

Should I expect 32% with a partially filled tank when I ask for 32%?

Yes *BUT* if they use prebanked 32% or similar you really should tell them the tank isn't empty and has whatever % in it already. Then they can either get the calculator out or drain it and fill from scratch. In an ideal world they'd verify themselves before filling but a lot of shops don't.

If I come in with a tank that has a different amount then request should I expect to pay 2$ more for a custom fill to get it where I want it? even if 32% is a cheaper option.

No. You pay for what you request not what they actually give them. The burden is on them to get it right.

I can understand variable pricing though. 32% is a standard mix, they probably use a lot of it so pre-blend and bank it in advance. Custom blends mean a staff member and compressor is tied up for the duration so more cost. Also, if the O2 content is higher the cost of that has to factor in too.