Etiquette if the shop doesn't fill the tank completely

[johndiver999]

Technical Diving and Recreational - Nitrox Calculator

nitrox calculator.

www.divelasvegas.com

none of those are relevant.

 

[Belzelbub]

I disagree. It’s the unknown unknown that requires the extra margin. And what are we really talking about? Getting a standard “fill” as opposed to being shorted.

What is the unknown unknown in your scenario? You have a finite amount of gas on your dive. A short fill means you may have to adjust your dive time and/or depth to compensate. It does not mean that you dip into your reserve. The only way a short fill will compromise safety is if there is just not enough gas to do the dive, or you plan to surface with 200 psi instead of 500 psi as you got 2700 psi instead of 3000. Neither of those is a good practice.

A short fill is an inconvenience. You didn't get what you paid for. It does not, however, in any way compromise safety. At least not by itself. If the diver does the dive anyway without enough gas, that's on the diver.

 

[Boarderguy]

You all are splitting psi over nothing. Way off track for a non pub thread...

 

[CT-Rich]

I disagree. It’s the unknown unknown that requires the extra margin. And what are we really talking about? Getting a standard “fill” as opposed to being shorted.

What is unknown? You pick up the tank, check the gas. Set up your rig, check the gas. You may at some point be disappointed, but it isn't an unknown. If 300 psi puts your dive into the scrub category, that's a plan issue.

If you can't catch a short fill before you leave the shop, that is a you issue. I am not sure what the "unknown unknown" is. Are you planning the invasion of Iraq?

 

[hilljo88]

What is unknown? You pick up the tank, check the gas. Set up your rig, check the gas. You may at some point be disappointed, but it isn't an unknown. If 300 psi puts your dive into the scrub category, that's a plan issue.

If you can't catch a short fill before you leave the shop, that is a you issue. I am not sure what the "unknown unknown" is. Are you planning the invasion of Iraq?

The unknown is not the fill, it's what could happen on the dive. "Men plan, God laughs." But enough on this digression. If you're comfortable managing your dives with short fills that's your prerogative.

 

[CT-Rich]

The unknown is not the fill, it's what could happen on the dive. "Men plan, God laughs." But enough on this digression. If you're comfortable managing your dives with short fills that's your prerogative.

I check my tanks before leaving the shop and I adjust my plans according to conditions on the ground. If I have a partially filled tank (for what ever reason) I will try to figure out how to make the most of it. I am still mystified by what what unknown unknowns you are talking about that would be different on short fill verses any other dive.

 

[Divin'Papaw]

I check my tanks before leaving the shop and I adjust my plans according to conditions on the ground. If I have a partially filled tank (for what ever reason) I will try to figure out how to make the most of it. I am still mystified by what what unknown unknowns you are talking about that would be different on short fill verses any other dive.

I agree with @CT-Rich here. Your gas plan is meant to cover the unknowns and the unknown unknowns. Be that rock bottom, back on the boat with 500 psi, rule of thirds ... whatever gas plan you are implementing for the dive. All of that you will adjust based upon your actual gas available at the start of the dive. If you end up with a short fill somehow and don't catch it until right before the dive, you adjust your plan and it essentially means your dive is either shorter or doesn't happen at all. But the gas plan and the safety stuff are non-negotiable. It's not like you are going to start your dive, get halfway through and then realize, "Crap, I got a short fill!!".

 

[wetb4igetinthewater]

There's this concept called min gas....

 

[johndiver999]

I agree with @CT-Rich here. Your gas plan is meant to cover the unknowns and the unknown unknowns. Be that rock bottom, back on the boat with 500 psi, rule of thirds ... whatever gas plan you are implementing for the dive. All of that you will adjust based upon your actual gas available at the start of the dive. If you end up with a short fill somehow and don't catch it until right before the dive, you adjust your plan and it essentially means your dive is either shorter or doesn't happen at all. But the gas plan and the safety stuff are non-negotiable. It's not like you are going to start your dive, get halfway through and then realize, "Crap, I got a short fill!!".

of course that would NEVER happen.. LOL..

 

[spool]

Today I watched our local tank guy get terribly confused with which way the valves on the filler yoke and my tank work. Finally, I said you are turning it the wrong way. Got several tanks filled with the banked mix of 36 and asked for one tank of 32% which requires mixing.

I didn't watch him do that tank, but when he gave it to me, he asked for me to let him know how close he got when I checked the mix. They never check their work- it is against their policy I guess. It came out at 24%, so I recalibrated the sensor and got the same reading.

I told him it was way off, and he said we can drain the tank and start over, but told me that the final mix also depends on how much gas was left in the tank from the prior fill. I reminded him that the tank was absolutely empty when I handed it to him, so that was a ridiculous and ignorant excuse- although I didn't say that. I asked him how me made the mix (using oxygen or diluting down the banked 36) and he said he used the 36, not o2.

So I took the tank out side, blasted some gas out of it, brought it back inside and then checked the pressure and it was 2000, so I took it back out and let a little more out and then asked him to fill it to 3000 with the 36% banked mix. He once again only filled it to 2800 and it checked out at 28% - my fault I should have done the math and drained it more, but I was frustrated and lazy.

The guy has worked there for months. After I left, I called the head guy in the shop at the time and explained the situation and after doing a little rithmatic on my phone figured out that he must have looked at the mix recipe for using pure oxygen (to start the fill), but instead just put about 500 psi of 36% and topped with air. The boss confirmed that is what the guy did. Pretty damn scary for that to be the guy's primary responsibility and he is apparently clueless.

The shop was cool and credited me for one fill (which I did not ask for) and when I got home I transfilled some more 36% from a hp tank to the lean LP tank, so I'm probably close to 30% - probably should do some more rithmatic.

A good reminder to check your mix, I guess.

Hahaha I didn't really consider this when I always hear "only trained can fill the tank". I haven't gotten to Nitrox yet. I thought it was because he was going to cause him or his equipment damage or injury. It's their liability, maybe they think they can shift on the customer if you're forced to check it yourself. It's hilarious/scary he's eyeballing it and says "lemme know how close I got". But at least you did the root cause analysis for them, so I'm sure it won't happen again