How to get a good fill

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dscuba
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How to get a good fill

Post by dscuba » Sun Feb 21, 2010 8:36 pm

I have what seems like a stupid question, but, when I get my tanks filled what constitutes full versus a short fill? If my tank says "3442 psi service pressure" does it mean I'm getting ripped off if I leave the store with ~3200 in it? (Even after leaving it overnight to allow it to cool off for a better fill). Because that's what's been consistently going on.

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sheahanmcculla
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Re: How to get a good fill

Post by sheahanmcculla » Sun Feb 21, 2010 8:53 pm

I would just ask to see the fill pressure when you pick them up. Then they will see that it's under and will top it off. If it says 3442 then I would want it at least that if it's been there overnight.

Just my thoughts.

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CaptnJack
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Re: How to get a good fill

Post by CaptnJack » Sun Feb 21, 2010 9:07 pm

Depends on how much a stink you want to make over ~242psi. Leaving them overnight doesn't do much if they aren't topping them off when they cool. The rated pressure is at 70F so its quite legal to pump them higher hot, i.e. to overfill them to cool to 3442psi. But most shops don't overfill them by enough so they still cool to what your seeing - of course then hooking up the whips again for 242psi isn't worth the hassles to them.
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Re: How to get a good fill

Post by Dusty2 » Sun Feb 21, 2010 9:13 pm

I have shops I go to and ones I won't and the base reason is I can trust them to fill my tank to at least what it sez on the tank. If a shop is filling your tanks to less than that they are not doing what you are paying them to do. A 120 filled to 3000 psi is basically a 100 so they have shaved 18% or more off of your bottom time. I always check my tank pressure right in front of the fill person if I am not at one of my regular shops and try to never leave a shop till it's up to rated pressure or above. I know for a fact that in cold weather a high pressure tank can lose as much as 500 PSI from a hot fill.

I know I'll get flack for this but that's my 2 PSI
Last edited by Dusty2 on Sun Feb 21, 2010 9:16 pm, edited 1 time in total.

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sheahanmcculla
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Re: How to get a good fill

Post by sheahanmcculla » Sun Feb 21, 2010 9:14 pm

CaptnJack wrote:of course then hooking up the whips again for 242psi isn't worth the hassles to them.



I agree, but for some reason 90% of the divers I filled tanks for thought they were getting ripped off if it wasn't filled to the rated pressure. I would fill past it for the same reason you mentioned, but others would not. I don't think it's that big of deal, but if a customer does...they are right and it should be filled.

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Re: How to get a good fill

Post by Dusty2 » Sun Feb 21, 2010 9:22 pm

sheahanmcculla wrote:
CaptnJack wrote:of course then hooking up the whips again for 242psi isn't worth the hassles to them.



I agree, but for some reason 90% of the divers I filled tanks for thought they were getting ripped off if it wasn't filled to the rated pressure. I would fill past it for the same reason you mentioned, but others would not. I don't think it's that big of deal, but if a customer does...they are right and it should be filled.


+1 on that. I do fills for people in port Townsend all the time and I consider it my job to give them what they are paying for. Otherwise I'm stealing time from them.

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Re: How to get a good fill

Post by airsix » Sun Feb 21, 2010 11:10 pm

Like I'm always telling my wife: Things are easier for everybody if you just say what you want instead of hoping I'll guess correctly.

When I drop off cylinders at certain shops I know I'll get a good fill, but at some places I know to be specific about what I expect. I want a good fill and am happy to allow them adequate time. I discuss pickup schedule and make sure we are in agreement, then I pad it as a goodwill gesture. I don't expect to get rush orders AND great fills. At pickup I check my mix and my pressure. If it's a bad fill I will politely remind the person assisting me that the pickup time was specifically agreed upon to insure time for topping off. And I wait for the topoff. It's annoying, but you only have to do it a couple of times before they figure out it's going to be easier to just have good fills ready at the agreed time. I'm also liberal with the thankyous when pressures and mix percentages are as they should be.
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Re: How to get a good fill

Post by Norris » Sun Feb 21, 2010 11:36 pm

airsix wrote:Like I'm always telling my wife: Things are easier for everybody if you just say what you want instead of hoping I'll guess correctly.

When I drop off cylinders at certain shops I know I'll get a good fill, but at some places I know to be specific about what I expect. I want a good fill and am happy to allow them adequate time. I discuss pickup schedule and make sure we are in agreement, then I pad it as a goodwill gesture. I don't expect to get rush orders AND great fills. At pickup I check my mix and my pressure. If it's a bad fill I will politely remind the person assisting me that the pickup time was specifically agreed upon to insure time for topping off. And I wait for the topoff. It's annoying, but you only have to do it a couple of times before they figure out it's going to be easier to just have good fills ready at the agreed time. I'm also liberal with the thankyous when pressures and mix percentages are as they should be.


I completely agree. I was consistantly getting short fills from this shop. 3000 on the nose for HP 100's. This was after leaving them overnight. I wrote an email explaining my expectations. Also assuring that I understand a short fill when getting them hot, but making TWO trips rather than one, I would really appreciate the full fill. I included in my email the question "Would you mind if I had staff check them prior to me leaving?"
The shop was very apologetic and agreed to me asking for a pressure check, as long as I came in there so he could meet me personally. I went in there and we had a fine discussion, and all is well moving forward. I also am super courtious and throw them thank you's around a lot. I have been getting great fills ever since, no problems.

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Re: How to get a good fill

Post by Fishstiq » Mon Feb 22, 2010 7:05 am

I don't usually sweat 100-200 psi, the time it "costs" me isn't enough to worry about. If I was picking up hp tanks though and repeatedly getting 3100psi or less, I would say its time to bring it to someones attention or take my tanks (and my money) elsewhere.
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Re: How to get a good fill

Post by LCF » Mon Feb 22, 2010 7:16 am

To answer the original question, which was how to get a good fill: Get your tanks filled at NWSD :)

Seriously -- I've had an occasional tank a little off the desired mix, but I have NEVER had a short fill there.
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Re: How to get a good fill

Post by Mattleycrue76 » Mon Feb 22, 2010 10:39 am

Good advice. I solved the problem by just buying big tanks. For rec. diving it's pretty hard to exhaust NDLs/thermal comfort on a 119 or 130 even if there filled a little short. I like to walk into the shops and get them filled on the spot for the most part, so this works well for me. A 130 shortfilled to 3100psi is still 117 cu ft :)

It just beats the hassle of being nitpicky about it. Of course in a perfect world all fills would be at or slightly over rated fill pressure.
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Re: How to get a good fill

Post by spatman » Mon Feb 22, 2010 11:03 am

Mattleycrue76 wrote:For rec. diving it's pretty hard to exhaust NDLs/thermal comfort on a 119 or 130 even if there filled a little short.


that's a good point, and in the end 200psi really isn't a big deal. but it does depend on your SAC rate and tolerance to cold. for example, penelope and i both dive hp119s. we'll do a 60+ minute dive where i end with 800psi and she'll have 1500 psi. at that point she's freezing and i could still dive for another 20+ minutes if i had the gas.

though that may change, now that she's got a warmer suit and i'm getting into the doubles thing. :biggrin:
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Re: How to get a good fill

Post by Nwbrewer » Mon Feb 22, 2010 11:10 am

dstucki wrote:I have what seems like a stupid question, but, when I get my tanks filled what constitutes full versus a short fill? If my tank says "3442 psi service pressure" does it mean I'm getting ripped off if I leave the store with ~3200 in it? (Even after leaving it overnight to allow it to cool off for a better fill). Because that's what's been consistently going on.


Are you checking your tanks when you pick them up? I always verify the fill pressure and mix before I leave the shop. If it's low, ask them to top it up. No one should have an issue with that.

As noted by Richard, 3442 is at 70deg F. It's winter. Are you checking you tanks at the site after they site in your car all day in the cold? 2 dives in January my tank pressure actually came UP when I got in the water. \:D/
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Re: How to get a good fill

Post by dscuba » Mon Feb 22, 2010 11:15 am

They are Nitrox fills so I always check it before leaving the shop at room temperature. I've only seen them at 3442 or higher once or twice ever, hence my dumb question here.

Yes these are HP120s and within NDL limits I have more than enough, it's just that I'm improving in my SAC and now I'm about at the point where I can sometimes make 2 dives on one of these tanks. If they're shortchanging me and the difference could nearly cut my nitrox cost in half I want to do something about it.

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Re: How to get a good fill

Post by Mattleycrue76 » Mon Feb 22, 2010 11:19 am

It actually bothers me alot more if I'm paying for a Nitrox fill. For me, the only reason I usually buy Nitrox is if I'm planning a deepish say 70-110 ft dive with a square profile. In that case I really want my money's worth.
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Re: How to get a good fill

Post by Dashrynn » Mon Feb 22, 2010 11:26 am

Mattleycrue76 wrote:It actually bothers me alot more if I'm paying for a Nitrox fill. For me, the only reason I usually buy Nitrox is if I'm planning a deepish say 70-110 ft dive with a square profile. In that case I really want my money's worth.


why would you need nitrox, just do some deco! :smt064 :breakdance: (its a joke btw)

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Re: How to get a good fill

Post by mz53480 » Mon Feb 22, 2010 11:30 am

spatman wrote:...and i'm getting into the doubles thing... :biggrin:

How's that going? I had a lot of fun figuring out how to stay trimmed out the 1st time I tried em.
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Re: How to get a good fill

Post by Nwbrewer » Mon Feb 22, 2010 11:33 am

dstucki wrote:They are Nitrox fills so I always check it before leaving the shop at room temperature. I've only seen them at 3442 or higher once or twice ever, hence my dumb question here.

Yes these are HP120s and within NDL limits I have more than enough, it's just that I'm improving in my SAC and now I'm about at the point where I can sometimes make 2 dives on one of these tanks. If they're shortchanging me and the difference could nearly cut my nitrox cost in half I want to do something about it.


In that case, ask them to top it up before you leave. No shop should have an issue with that.
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Re: How to get a good fill

Post by scobanro » Mon Feb 22, 2010 12:25 pm

Fills have alway been a good fireside chat,
I think its all about HEAT, for every degree in temp you loose 5 psi. When someone hot fills a tank that warm you feel on the outside is as hot as a furnace inside. The metal is 1/2 thick. Think about it, you fill through a small tube at the end of your valve. Air reaches supersonic speeds coming out of that tube. Now supose there is a tiny little burr anywher in that air stream. Poof you got detination. small but its there. that means monoxide! BAD. So remember what your asking when you want them to hurry.
I say slow and cool will do. You bet you should talk to the shop and inform them to be slow when they go. And I too agree you should have your tanks filled to operating pressure, HP tanks or LP tanks. They should be full. I have never heard anyone with an LP tank complain about getting a 3000psi fill, hmmm almost a 1/4 more air. no complaints there :biggrin:

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Re: How to get a good fill

Post by CaptnJack » Mon Feb 22, 2010 12:43 pm

Carbon monoxide is not created in the valve. Its either entrained by the compressor intake or generated in situ by the partial combustion of the compressor oil. Oil combustion is not very common here in the PNW since our ambient temps are by and large low. Its a concern with poor filter/oil maintenance practices in the tropics and has nothing to do with fill rates.

If the valve seat partially ignites duing the partial pressure filling process (which not all nitrox fills are made by) you will know it, the gas will taste & smell horrible - something like ammonia.

You are correct that 1F = roughly 5psi increase. 130F gas coming out of the compressor or banks will cool from 3500psi to 3200psi at 70F. This is what I see on my typical fills at home (300psi drop).
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Re: How to get a good fill

Post by camerone » Mon Feb 22, 2010 1:07 pm

CaptnJack wrote:You are correct that 1F = roughly 5psi increase. 130F gas coming out of the compressor or banks will cool from 3500psi to 3200psi at 70F. This is what I see on my typical fills at home (300psi drop).

...and gauges are not all the same. If you're measuring on a dive-grade SPG, you should consider yourself "within" maybe 300-ish PSI of what the actual pressure is, either way. If you're going home and checking your tanks, and then complaining, then at the least, you owe it to the store to check side by side with their gauges, at the same temperature next time you pick up your tanks.

I know on my setup at home, the compressor pressure gauge is not at all equal to the digital gauge on my mixing whip (but I understand roughly how they correlate to one another based on experience, and I trust the digital gauge more...) Those two do not agree perfectly with the six or seven SPGs that also litter my garage...

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Re: How to get a good fill

Post by Agent 47 » Wed Feb 24, 2010 6:22 pm

The best way I know to get a good fill is
1. develop rapport with the dive shop any dive shop should fill your tank to rated pressure but you may need to put in a little time and gentle encouragement to get a little more. Remember some shop workers and owners may be very cautious about overfilling tanks I sometimes even find myself squinting my eyes and covering my jewels when bumping a tank a couple PSI over so if the filler is uncomfortable with the idea don't push to hard. I still remember the first time a burst disk went on me, I think it was a couple months before my hiney hole finally un-puckered and I flately refused to overfill a tank for quite a while after that.
2. drop it off and leave it. even when shops use a water tank often the tank will still cool for an hour or so after filling so if you are in a hurry you may not get a good fill especially if the shop is unwilling to jack it past the rated pressure to allow it to cool down to the pressure stamped on the tank.
3. Make sure they start filling it before you leave. If you just drop the tank and leave saying you will be back in two hours to pick it up chances are good they will start filling it in one hour forty five minutes especially if they are busy. I suggest you plan on doing something else for an hour or so while the tank is filled, bring your tank in and have them start the fill same as if you are going to take it right away. once the fill is almost done say you need to go do some stuff and don't want to leave your tank in the car while you do it and would it be ok to come back in an hour or so. make sure your tank is marked, preferably with your name, when you come back ask if they have a gauge you can borrow or comment on how its now "nice and cool" and would they mind toping it up for you. Any shop worth there salt should have absolutely no problem doing this for you. good fills are what can make or break a dive shop and they should absolutely be willing to work with you on this. Remember we are all divers and we all know the value of a good fill so don"t be shy about asking.
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Re: How to get a good fill

Post by H20doctor » Wed Feb 24, 2010 10:59 pm

id say its because of Heat.... your gonna loose 2 to 3 Hundred PSI when it cools down... , also some shops Gauges arnt on at all and need to be calibrated.. Get in good with the dive shop and check your tanks before you leave.. Better yet buy one of those tank pressure thingys that tell pressure... that way you can check it right then and there.. I get the best fills at AM/PM !!! and they only cost .50 cents
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Re: How to get a good fill

Post by no excuses » Thu Feb 25, 2010 1:41 am

buy youre own compressor and fill them at home, then you can save the big bucks also :evil4:

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Re: How to get a good fill

Post by Mattleycrue76 » Thu Feb 25, 2010 9:43 am

no excuses wrote:buy youre own compressor and fill them at home, then you can save the big bucks also :evil4:


I really hope you're still saying that on the other end of your little Rix project. It would keep the hope alive for guys like me.
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