Testing your breathing Gases Prior to Diving

[TSandM]

When we get air fills from a shop that also pumps Nitrox or helium, we analyze the air. Not only is it possible that it has too much oxygen in it, it's possible it doesn't have ANY, if it got hooked up to the wrong feed. We own an analyzer, because we DO dive Nitrox, so it only takes a minute to check the air tanks, too.

If someone owned tanks that only had air in them, and got their fills at a shop that doesn't pump anything but air, I see no reason to analyze those tanks. Many people's fills don't meet all those criteria, though.

 

[FM1520]

Give me a break. That's an EANx diver not an OW diver.

yea, I agree and most knew what you meant.

 

[HIGHwing]

Whether the shop is capable of pumping Nitrox, Trimix, or fairy dust, you never know where or what a rental tank was doing prior to it being returned. All it takes is someone calling a dive, the tank gets returned, topped back with air, and put with the "air-only" cylinders. You might not dive Nitrox, the shop might not pump it, but it could easily be on your back.

 

[lindenbruce]

There's no helium at my shop.

Sorry, your aren't going to convince me. Millions and millions of air tanks are dived each year without incident. I have other dangers to give more priority.

---------- Post added August 11th, 2013 at 07:20 AM ----------

Fwiw an ow diver wouldn't even know how to analyze a tank. They haven't been introduced to the concept yet.

Which is actually pretty sad because it is so darned easy to analyze your tank. You would think it would be part of a certification to teach people to check their tank mixes. It seems as though at least one person has an analyzer on a dive boat if not the DM. And you know fill stations have them. I don't think any fill station would have a problem if a customer wanted to use their analyzer to confirm a tank mix before walking out of the shop. I know it was not part of my OW certification. Percentages were discussed of course in the classroom sessions, but the actual act of learning how to test a tank and doing it were not part of my OW training.

As far as rec diving goes I don't get my undies all tied up in a knot over checking my tank mix each and every time. NOW, if I'm tecking I'm testing each and every tank because gas management and planning is an integral part of that activity.

B.

 

[fnfalman]

Does that boat rent tanks out? Is it possible that the last user filled it with something else? There is a current thread on making a cheap fill whip so I'd argue that anything is possible.

It isn't that difficult or time consuming.

Sent from my Nexus 7 using Tapatalk 4

Don't know and don't care. I have my own tanks that I take with me.

---------- Post added August 12th, 2013 at 12:00 AM ----------

We should look at this from the risk vs. cost. The risk is that one can get injured or die due do using a wrong mix. The cost is 100-300 USD upfront , 100 for a new sensor every few years and couple of minutes before the dive one sharpie every year or so and masking tape for stickers. With that cost I just cannot see reasons what could stop from investing into one of these devices.
Even if we speak air filling only which steel tanks it is still possible that air can get hypoxic after sitting in the tanks for a while.

A few years back an old Assie diver donated his filled tanks and they were last filled at least three decades ago. A study of the content showed that the air was breathable and some scientists were using the air to test against current atmosphere for smog content.

So yes anything is possible but how probable it is...that's another story.

---------- Post added August 12th, 2013 at 12:03 AM ----------

Whether the shop is capable of pumping Nitrox, Trimix, or fairy dust, you never know where or what a rental tank was doing prior to it being returned. All it takes is someone calling a dive, the tank gets returned, topped back with air, and put with the "air-only" cylinders. You might not dive Nitrox, the shop might not pump it, but it could easily be on your back.

Some of us don't use rental tanks.

 

[HIGHwing]

I have 30 cylinders myself, but I go on frequent trips to the Caribbean and find rental cylinders quite a bit easier than bringing our own stages and doubles. Rental cylinders are simply a function of practicality in some locations.

 

[corvettejoe]

Most dive shops SHOULD have an analyzer, especially if they do anything besides air.

Before I owned my own tanks, I used to rent them. We would put all kinds of mixes in them before returning them at the end of the week.
I've seen some dive shops empty the tanks completely before refilling. I've seen others simply hook them back on the fill whips and ready them for the next renter without even checking what was in them.

Even owning my own tanks I have no idea what's in them until I analyze them. All my tanks are o2 cleaned and can have pretty much anything in them at any given time from air to 100% o2. The stickers on the side mean nothing except "oh it's been inspected and has/hasn't been o2 cleaned".

And that said, I ALWAYS analyze them at the shop before I leave because they have the chance to fix it at the shop. I don't own my own analyzer yet, so using the shop's costs me nothing. Once you're at the dive site, you have no way of knowing what you're breathing, and no way to fix it without having to pack up and head to another dive shop to fix the problem.

I think a simple check is worth my life.
I only recently started checking for CO as well after a friend had a friend die from it being in their tank.
Its rare, but IT CAN HAPPEN.

 

[tplyons]

I test my oxygen cleaned tanks every time. Sometimes I dive air, sometimes I dive Nitrox, and sometimes I'll have some residual Nitrox and top off with air. These always have a different mix and therefore always get tested. I mostly do my own blending, so I test when I'm done mixing, test when I fill out the log, and test again before I dive it in case the gas wasn't completely homogeneous when I analyzed it at the shop. If I'm with a dive op that I can't do my own mixes, I'll analyze before I leave (as required) and once again before I dive it in case it wasn't completely homogeneous.

I have two more tanks that are air only. I fill those myself at the shop; I don't bother to test them because I filled them, and I know what was put in. But once again, if someone else fills them, they get tested. Despite the fact that they aren't labelled for Nitrox, we're all human. And frankly, the only person who can make sure YOU don't dive with the wrong gas is YOU.

 

[seattlepaul1975]

Every time I pick up Nitrox at my local dive shop, you have to test it verify the % and sign log book with it...put the tape on your tank stating the % and MOD. I see no reason why you would not test your tank as it takes a minute per tank if that.

 

[fnfalman]

I have 30 cylinders myself, but I go on frequent trips to the Caribbean and find rental cylinders quite a bit easier than bringing our own stages and doubles. Rental cylinders are simply a function of practicality in some locations.

When I travel overseas, then I'll worry about analyzing rental tanks.

The whole point of this silly thread is somebody thinks that paranoia is a solution to safe diving.