Dive shop only filled tank to 3900 psi🤔

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kkarmical

kkarmical

Member
Mar 22, 2016
768
93
CA, United States
This was all on me, I have become so comfortable with the shop I use, I didn't check the fill pressure until I got home, but by then shop was closed for the day.

I've had warm fills cool down and be only 4300, or even 4200, and I just chalk it up to the game.

But 3900 is just not acceptable, so had to go back today and have it topped off by the same employee who wouldn't stop apologizing, though he did try and say maybe my tank had a leak, which I let him say a couple times before telling him I just had it hydro tested and routine maintenance performed.

I'll never not check tank pressure again though, fortunately the shop is only a few minutes away.
 
It's not necessary employee fault.

It's wintertime, don't know how cold nights are in your area.

My tank was filled at local airgun shop

Next morning I was trying to fill my Pulsar and it stopped a few seconds later, I was what the f...

Sure enough, I took warm tank from the shop and after freezing night in my car, it was just 3800 psi

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I live in California, it's just not that cold. When he topped my tank off from the huge shop compressor they have it was two stages.

1st filled to exactly 3900psi, then he had to physically push a button and start the second part of the fill the rest of the way.

It was obvious to me since they have new employees, that the young new guy that was tasked with the grunt work, just didn't do the second part of the fill, especially when he turned a little red in the face😉
 
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well the good old touch test can work, before leaving feel how hot your tank is. if really warm mine drop 2-300 psi. in the shop, while i wait. i've been to shops that fill an extra 200 knowing it will cool down.that much. also been to shops who put tanks in a water trough to fill. this was fastest as the tank cooled down to fill pressure quickly. either way if you paid for 4500 you should get it. maybe a little waiting around will get you your proper fill.
 
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A few psi isnt something to get work over about and get mad. Kinds silly imo. It's only a few psi. I have my own compressor and when I fill my 75cf tank tp 4500. It would drop to like 4200 psi. Nothing to get work over about. If they like dont bother to fill your tank and charge you for it. That's something different. Few drop in pressure isnt a big deal. One or two fill on a gun and it will drop to that pressure anyways.
 
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well the good old touch test can work, before leaving feel how hot your tank is. if really warm mine drop 2-300 psi. in the shop, while i wait. i've been to shops that fill an extra 200 knowing it will cool down.that much. also been to shops who put tanks in a water trough to fill. this was fastest as the tank cooled down to fill pressure quickly. either way if you paid for 4500 you should get it. maybe a little waiting around will get you your proper fill.
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I dropped my tank off, then left went home to watch Army / Navy game, no need to wait around, this shop just calls you when it's ready to pick up.

It's a dive shop that provides full scuba training and certification, and has the largest Bauer compressor I've ever seen, and provides very dry air, and a very slow fill, thus tanks never get warm or hot.

It was my fault for not checking my tank pressure, if I had done so, they would have corrected it on the spot, it was a honest mistake.

If I ever saw someone putting my tank into a water trough I would immediately grab my tank and leave, because if they are filling it so fast that the tank needs to be cooled, that to me screams moisture to me, I'd rather find some place else or.just buy my own compressor which I will eventually get around to doing. 

I would have bought a compressor already, had I not found this dive shop, and this really isn't that big of a deal, going forward I will always check the pressure before leaving, problem solved until the next time I forget to😉
 
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Shops fill in water for added safety more than cooling. If a tank does go under water the risk of injury is much lower. Same reason they hydro test in water.

To get the max pressure you need to fill, pause and top off...just like what you need to do with your gun. Most shops don't bother with the top off. This is even more frustrating when all you have are 3000 psi aluminum tanks.

I finally got my own compressor to be done with dealing with it.
 
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@KKarmicall

If I ever saw someone putting my tank into a water trough I would immediately grab my tank and leave, because if they are filling it so fast that the tank needs to be cooled, that to me screams moisture to me, I'd rather find some place else or.just buy my own compressor which I will eventually get around to doing. 



I don't understand how you think that this process will add moisture to your tank. It doesn't matter how fast or how hot your tank gets. Moisture is either in the supplied air or not by way of separation and filtration. Contrary to some misguided beliefe, heat has absolutely nothing to do with creating moisture. Water can't be created or eliminated, it can be converted to gas or ice but can not just condense from nothing by applying heat. Keeping the tank cool whilst it is being filled means that it can be filled to almost the desired pressure without having to do in stages which usually takes two visits to the shop instead of one. Some places will fill your bottle to 4800 PSI because they know when it cools it will be under the max recommended pressure. All dive shops have their own methods, you are lucky you have one that can fill your bottle to 4500 PSI.
 
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@KKarmicall

If I ever saw someone putting my tank into a water trough I would immediately grab my tank and leave, because if they are filling it so fast that the tank needs to be cooled, that to me screams moisture to me, I'd rather find some place else or.just buy my own compressor which I will eventually get around to doing. 



I don't understand how you think that this process will add moisture to your tank. It doesn't matter how fast or how hot your tank gets. Moisture is either in the supplied air or not by way of separation and filtration. Contrary to some misguided beliefe, heat has absolutely nothing to do with creating moisture. Water can't be created or eliminated, it can be converted to gas or ice but can not just condense from nothing by applying heat. Keeping the tank cool whilst it is being filled means that it can be filled to almost the desired pressure without having to do in stages which usually takes two visits to the shop instead of one. Some places will fill your bottle to 4800 PSI because they know when it cools it will be under the max recommended pressure. All dive shops have their own methods, you are lucky you have one that can fill your bottle to 4500 PSI.
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Filling tank so fast that it needs to be in a water bath is to me an indication that they may not be the best source of air, imo it's a shortcut, and they may be cutting corners elsewhere, ie filtration, thus moisture in air...

I've been around scuba tanks long before I started using hpa tanks, have yet to see this water bath method done, maybe that's a good thing about being in an area with so many dive shops, plenty of sources to use that don't go to such extremes.

I have had my tank filled to 4700psi before, when it cooled it was 4300 psi, and the guy that filled it was very unprofessional, thus I never went back, and just found another shop by asking friends that are divers which ones they use.
 
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Well I have breathed hundreds of tanks of air from dive shops and most have used water bath cooling, aluminum and steel tanks. The air has been dry. As far as the comment about the CF tank if they have a problem with a wet bath fill I don't want to be around them, wonder if that employee changes the spark plugs in his diesel. Also the hyro is done in a water tank. Ever felt a tank sitting in the sun hot on one side cool on the other.
 
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It's very common in big fill facilities to fill steel and aluminum tanks in a water bath so the tank does not get so hot and achieves a 'fuller' fill after it normalizes to ambient.

But carbon fiber and aluminum are galvanic to each other and the epoxy acts as an insulator. There is always the possibility that submerging a tank on a regular basis will introduce water through a pinhole or flaw and start corrosion on the exterior of the aluminum bladder. Hence fill facilities in the know don't use a water bath for composite cylinders.

In hydro shops, yes bottles are filled with water and then put into a big tank of water for the hydrostatic test BUT THEN the bottle is immediately put on a dryer. It's a pipe that is vertical and the bottle is set over it and hot air goes up into the bottle and then out the neck and dries all the internal moisture and the heat also dryes the CF shell too for an hour or more so no external corrosion problems.. The valve is reinstalled with the bottle hot so as little atmospheric moisture as possible is trapped inside.

Another reason some shops fill tanks in water is that if the tank fails a lot of the blast will be absorbed by the water, it's a safety measure. That's why some shops fill behind a wall or barricade or put the bottle into a safety cage.

Carbon Fiber tanks could withstand quite a bit higher pressure by design, it's very conservative. So filling to 4800 so it cools down to 4500 is relatively safe IF THE BOTTLE IS IN GOOD CONDITION.

Note also that the certification laws for CF bottles expected them to be used in hot places like fire environments (SCBA bottles on a firefighters back in a fire might get to 160 degrees, that's why the bunker gear they wear is thick and heavy, to protect them from that heat for brief intervals [I've trained as a firefighter too]), stored in hot vehicles or mounted in airplanes sitting at an airport in the sun (I've seen the inside of a plane reach 200 degrees on a sunny day!) HOW MUCH EXPANSION AND RISE IN PRESSURE DO YOU THINK HAPPENS THEN? It's designed for it. So filling to 4800 or 4900 which then immediately cools down to 4500 will not cause death and destruction.



Here's the link to a thread I did about CF bottle strength and life .https://www.gatewaytoairguns.org/GTA/index.php?topic=158055.0

Here's a direct link to an important article referenced in that thread for those who don't go to GTA

.https://6d2eecd7-e7a3-4f9f-b0df-1269dfd13c8f.filesusr.com/ugd/d00b78_72625b919876457fb9191418c1259c6b.pdf
 
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My first fill on my Great White was at a Dive Shop, the owner looked at my tank and said if this tank fails we are both dead and my shop will be leveled. Like mentioned above tanks in water will not save you. Last year I was diving in Utila Honduras and the year prior a Scuba Tank was overfilled, It blew outside on the dock and killed a girl.



Alec Peirce Scuba

https://www.youtube.com/watch?v=ngM0TeW44Zc&lc=UgxnLKVd0pedMJ7Wnv94AaABAg.8yx8Z5Cp3mu8yzI0id9FGX

Water tanks, baths they call them, are not used today by modern stores. They've been shown to be detrimental to the safety of the operator and diver and not that good for the tank either. The cooling down to room temperature is done by letting the tank sit in a room for a while. I know too well that divers want to get a fill and get going but a good tank kill should at least 30 minutes and preferably twice that. Alec


 
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Totally agree on not using a water bath, as I said, especially for carbon fiber cylinders.

Reasons I bought my own fill compressor from NSA (Nelson Specialty Ammo) was getting fills at paintball and scuba shops here in the US where some kid in a hurry filled too fast which overheated the cylinder, causing low fills when it cooled down. And also, the uncertainty of whether or not their air was really dry enough. Good luck asking them to fill slow.

On overfilling, what they are talking about is the practice of filling MUCH higher, like 25% or more. A real problem in foreign countries where they will fill a questionable 3000 scuba tank to 4000, time after time after time. Absolutely damages the life of the tank and endangers everyone. Those same places have a problem with moisture too and lack of hydros or fake hydros is a real dangerous continuing problem. I worked some as a Dive Master and we would insist on a random tank be bled down and the valve pulled and I would look inside. Some nightmares of corrosion and there were dive shops so bad we blacklisted them from our tour groups use.

I know of a case where in June in Texas, a shop filled a tank to 4600 and the naive bottle owner, new to high pressure air and airguns, took the bottle home and thinking it was ruined, bled it down and drilled holes in it to decomission it. Have a little common sense people!


 
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