LDS Scams

[MXGratefulDiver]

If you will underfill a cylinder, you would probably also overfill it.

Not so ... those who chronically underfill cylinders do so because when the cylinder reaches the rated working pressure they close the valve, regardless of temperature. Since it's unlikely in the extreme that a just-filled cylinder will be cooler than ambient temperature, there will never be a case where the "monkey" overfills the cylinder.

It has also been my experience that those who chronically underfill cylinders (due to a concern about exceeding the pressure rating) will happily top off your cylinder when it cools.

Furthermore, the only thing that would make an overfill "dangerous" is if your burst disk were improperly installed or had been tampered with. Otherwise, all this talk about exploding cylinders is just Internet hyperbole.

Many shops have a policy that they will NOT overfill cylinders, for any reason. That is not a scam ... it's a business decision. As a business, their only responsibility to you is to make sure you are informed about shop policy regarding fills. As a customer, you then have the ability to choose to take your business elsewhere. There is no law that requires a shop to overfill your cylinder to "adjust" for potential temperature differences ... nor do you, the customer, have any right to stipulate what safety limits the shop places upon it's business and employees.

But it is fun to complain on the Internet, isn't it ...

... Bob (Grateful Diver)

 

[MXGratefulDiver]

In freezing temperatures, a cylinder is "full" at below its working pressure. The proper fill pressure is entirely dependant on the temperature; if this is not understood and compensated for (in BOTH directions!) then the people doing the filling don't know what they're doing.

I can't imagine any LDS filling cylinders in freezing temperatures ... certainly that's beyond anything I've ever experienced. In your (unheated) garage perhaps, but every LDS I'm familiar with has a fill station inside the shop.

I think it would be more productive to discuss realistic scenarios ...

... Bob (Grateful Diver)

 

[Genesis]

Many shops have a policy that they will NOT overfill cylinders, for any reason. That is not a scam ... it's a business decision. As a business, their only responsibility to you is to make sure you are informed about shop policy regarding fills. As a customer, you then have the ability to choose to take your business elsewhere. There is no law that requires a shop to overfill your cylinder to "adjust" for potential temperature differences ... nor do you, the customer, have any right to stipulate what safety limits the shop places upon it's business and employees.

... Bob (Grateful Diver)

They are not overfilling the cylinder if they fill it to its rated pressure at the temperature it is at when filled.

If, for example, they are "hot filling" a cylinder that reaches 130F when being filled, then "full" for a 3000 psi cylinder at that temperature is ~3330 psi. If they claim they will not "overfill" that cylinder, but refuse to fill it beyond 3,000 psi at that temperature, then they're committing fraud - because full at that temperature is NOT 3,000 psi, it is 3330.

If they don't KNOW that full is 3330, then you might excuse (or educate) them. If they do know that full is 3330, then they're stealing approximately 11% of your gas from you, given that they're charging you for a "full fill" (and not 90% of one.)

On the converse, if it is currently 32F out, then "FULL" on that same cylinder is ~2800 psi at that temperature. If they claim that they don't "overfill" a cylinder but will fill and then top that same cylinder to 3000 psi @ 32F, then they are lying as well, and this time doing exactly what they claim they won't do - they're overfilling the cylinder!

Indeed, if you take the cylinder filled to 3000 psi @ 32F inside and let it warm up, you will find that it registers roughly 3200 psi when it reaches room temperature.

Again, if the shop doesn't actually understand this, then they need to be educated. If they DO understand this then its being done for a different reason - go ahead and figure it out, but it doesn't reflect well on them at all, and you'd be wise to go somewhere else.

BTW, of the three shops around here that I've dealt with, only one has the fill station inside, and our temperatures DO approach freezing at this time of the year.

 

[The Chairman]

Has anyone ever worked out how much providing air actually "costs" the shop??? Check out electricity, compressor/filter upkeep, employee time involved and the like, and you are going to find that they LOOSE money with every fill. Their only hope of re-couping these losses is for some of you tightwads to buy something from them.

You can call it a scam, but it's one in reverse. We as divers have scammed the industry into giving us cheap, cheap fills. No wonder the shop owners have such bad attitudes when someone asks them to top off their tank from 2975 to 3000! Then we complain why everything costs so much... get a clue. Internet entities do not have to pay for all of this and can offer much lower prices. Just be careful, or your refills will have to be mailorder some day.

 

[Genesis]

Has anyone ever worked out how much providing air actually "costs" the shop??? Check out electricity, compressor/filter upkeep, employee time involved and the like, and you are going to find that they LOOSE money with every fill. Their only hope of re-couping these losses is for some of you tightwads to buy something from them.

You can call it a scam, but it's one in reverse. We as divers have scammed the industry into giving us cheap, cheap fills. No wonder the shop owners have such bad attitudes when someone asks them to top off their tank from 2975 to 3000! Then we complain why everything costs so much... get a clue. Internet entities do not have to pay for all of this and can offer much lower prices. Just be careful, or your refills will have to be mailorder some day.

Nonsense Pete.

I know exactly what it costs to run a compressor - I own one. I know what it costs for me to fill a tank with either air or any particular blend of Nitrox.

This is for hyperfiltered air too Pete; if you "only" want Grade E its a LOT cheaper, since a huge part of the cost (like half!) is the hyperfilter processing cost.

And, I might add, this is in "small quantity." There are economies of scale in this; in particular, small filter cartridges don't cost much less than big ones, but provide a LOT less gas capacity before they have to be changed. As a consequence the per-tank processing cost for a personal compressor is significantly higher than that for a shop.

Shops don't lose money on fills Pete. That's a common claim used to "justify" the other things they do - but its false. If it was true then it would cost me MORE to own my compressor and fill my own tanks than it would to have a shop fill them.

In fact, it costs me less - about half as much - to "do it myself."

BTW, electricity is literally "lost in the noise". A 10HP motor draws about 10kw (if its 70% efficient - 3-phase motors, and most big ones are, do considerably better than this.) That's sixty cents an hour to run, roughly, in Florida (6c/kwh), but that compressor produces ~10cfm (a rough average is 1cfm per hp) or 600cf of gas at the compressor's rated working pressure. That is, the electricity to fill your tank costs the shop a whole eight cents, and I'm being charitable here by understating efficiency considerably.

THE big cost factor for a breathing-air compressor is filter time; indeed, about 75% of the cost is contained there. ALL of the rest, including the depreciation allowance, power, oil, a repair budget, etc - makes up the other 25%. This assumes that you actually use a realistic life estimate for the compressor and do not attempt to play the game that it should have its cost fully recovered in a year - for a piece of capital equipment that has a service life that in most cases exceeds ten years!

I have in the past posted a VERY detailed breakdown of actual operational costs for my home unit.

 

[chrpai]

Has anyone ever worked out how much providing air actually "costs" the shop??? Check out electricity, compressor/filter upkeep, employee time involved and the like, and you are going to find that they LOOSE money with every fill. Their only hope of re-couping these losses is for some of you tightwads to buy something from them.

You can call it a scam, but it's one in reverse. We as divers have scammed the industry into giving us cheap, cheap fills. No wonder the shop owners have such bad attitudes when someone asks them to top off their tank from 2975 to 3000! Then we complain why everything costs so much... get a clue. Internet entities do not have to pay for all of this and can offer much lower prices. Just be careful, or your refills will have to be mailorder some day.

Pete- Why do you need to be so abusive towards divers? Is Scubaboard for the diving community or is it a front for the diving industry now?

 

[plsdiver4377]

Along the same line as the above disussion I have been told by a LDS owner that a Neutral AL80 held the same amount of air when filled at 3000psi as well as 3300psi, this tanks working pressure (he also stated that a standard AL80 would sink when empty). Being fresh outta the turnip patch at the time I didn't argue. I did however go home and do a little research and go back to this shop (I hate being lied to) and have a little chat with this person. Basically I told him that either he needs to update his personal information or stop lying to his customers. He took offense to this and proceeded to deny that the information I brought in was incorrect. Just to prove a point I had brought one of my cylinders (which was bought from him) to the store emptied, then threw it in the pool. I don't think he appreciated the result but he has never told me anymore mis-information/lies that I know of. Of course I've only gone back when I needed something real bad and couldn't get it elsewhere.

 

[The Chairman]

Chrpai,

no matter what I say, you will find fault with it. That's your perogitive. I am not sure how I was "abusive" here. I guess it's OK to call what the shops do a scam, and when somone stands up for them, you call that abusive? Please check the dictionary for the proper meaning and usage. That's really too funny. I like to look at BOTH sides of the coin.

So Karl, you have how big of a compressor? And would you share it's cost with us? How many watts does it consume? How many fills of "hyper filtered" air do you get for your filter stack.

You can rail against the shops... but all of this costs money. Commercially rated compressors cost money, and so do the lights, the insurance, yada, yada, yada. I saw where a "dive shop to be" figured all of this out, and I can tell you that WE would not pay that much for each fill. Add on top of this some kind of profit margin, and I think he would have had to charge $16 per tank to really make it worth his while.

Air fills are loss leaders to get you in the door... sorry if that's abusive to you chrpai. But the scam is reversed for this one.

 

[The Chairman]

Hey Chrpai...

don't forget to report my post again.

 

[chrpai]

Along the same line as the above disussion I have been told by a LDS owner that a Neutral AL80 held the same amount of air when filled at 3000psi as well as 3300psi, this tanks working pressure (he also stated that a standard AL80 would sink when empty).

Well sure, if you hot fill the hell of out a tank and fill it to 3300psi and then allow it to cool, it will hold the same amount of air as the tank that was filled to 3000psi slowly. But I'm sure thats not what he meant.

AL80 sink when empty? I don't think so....