GTA
Support Equipment For PCP/HPA/CO2 and springers ,rams => Support Equipment For PCP/HPA/CO2 => Topic started by: the sloth on March 05, 2014, 10:47:46 AM
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Hi everyone - I'm shopping for a fill setup and need some guidance.
I have two Marauders and want to have an alternative to pumping during hot summer outings. I like the idea of a portable tank for camping and travel, so I've been looking at "guppy" tanks. Would like to buy new. So far I've come across Joe B's tank (18 CF @ $389) and PA's Air Venturi/Ninja PB tank (16.2 CF @ as low as $250 with discounts).
So I have to ask, is Joe B's slightly larger tank really worth the extra $100+? The hardware looks robust, but will I even notice the difference? How is the Air Venturi tank quality-wise? Are there any other manufacturers I should consider?
Thanks all for your help.
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I can tell you from experience that you can't go wrong with Joe's tanks. Built to the highest quality,well worth the extra bucks. I have one of his guppy tanks.Go for it and Joe is a great guy to boot.
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I'm in a similar situation. Looking for a portable tank for my dad. Another option you have is the Benjamin tank from Crosman. DIN valve, microbore hose, and priced between the Ninja/Venturi and Joe B. So far, I'm favoring the Ninja because it comes with a male foster fitting. I can fill by just connecting to the bigger tank. Crosman and Joe B tanks will require another buying an adapter.
As for size.... Look at the actual CI stated on the label. I've been told that Cu Ft numbers can differ based on how the calculations are done.
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;D After looking at all the tank setups I opted for Joe B's Guppy set up with dual gauges and a Freedom 8 compressor . No hands on yet with the tanks yet but they just look very robust and I have not seen any negative posts about his tanks. I agree with the portability for a carry setup and will probably pick up a back pack for the field
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Hi everyone - I'm shopping for a fill setup and need some guidance.
I have two Marauders and want to have an alternative to pumping during hot summer outings. I like the idea of a portable tank for camping and travel, so I've been looking at "guppy" tanks. Would like to buy new. So far I've come across Joe B's tank (18 CF @ $389) and PA's Air Venturi/Ninja PB tank (16.2 CF @ as low as $250 with discounts).
So I have to ask, is Joe B's slightly larger tank really worth the extra $100+? The hardware looks robust, but will I even notice the difference? How is the Air Venturi tank quality-wise? Are there any other manufacturers I should consider?
Thanks all for your help.
another thing to consider is the amount of fills you will be able to get out of the small 18cf tanks,
maybe not a consideration since you have a pump,but,
for filling the mrod,
if you fill to 2900psi and refill at 1900psi you will only get 12 or 13 fills out of the guppy tank before needing it filled.
pumping got very old to me,which is why i went with joe b's great white tank (97cf) and couldnt be happier (65-70 fills)
but like i said,since you are currently pumping ,the amount of fills may not be of concern.
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Hi everyone - I'm shopping for a fill setup and need some guidance.
I have two Marauders and want to have an alternative to pumping during hot summer outings. I like the idea of a portable tank for camping and travel, so I've been looking at "guppy" tanks. Would like to buy new. So far I've come across Joe B's tank (18 CF @ $389) and PA's Air Venturi/Ninja PB tank (16.2 CF @ as low as $250 with discounts).
So I have to ask, is Joe B's slightly larger tank really worth the extra $100+? The hardware looks robust, but will I even notice the difference? How is the Air Venturi tank quality-wise? Are there any other manufacturers I should consider?
Thanks all for your help.
another thing to consider is the amount of fills you will be able to get out of the small 18cf tanks,
maybe not a consideration since you have a pump,but,
for filling the mrod,
if you fill to 2900psi and refill at 1900psi you will only get 12 or 13 fills out of the guppy tank before needing it filled.
pumping got very old to me,which is why i went with joe b's great white tank (97cf) and couldnt be happier (65-70 fills)
but like i said,since you are currently pumping ,the amount of fills may not be of concern.
I'd love to get a large tank, but it's just not in the budget. Plus I'd lose some portability, which is important to me. Throwing a small tank into a backpack for a day out sounds perfect, and 10+ fills should be more than plenty. I don't mind pumping at home - gives me an excuse for a little exercise, could definitely use it - but when I'm out in the woods or at a shootin' BBQ with a stomach full of food and beer, pumping is the last thing I want to do. :)
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Also, check with Tim @ Mac1 Airguns (he has a Gate here on the GTA), he sells the Ninja Fill Station in a slightly customized form, you might like what you see....
Bob
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I have a JB's guppy tank and I am very happy with it. Perfect for a day in the field for me. But then you have to fill it quite frequently. I don't like to see my shoebox working so hard every week. I read somewhere that a 44 cf tank is a good compromise between portability and number of fills. Does anyone knows the dimensions and weight of a 44 cf tank? Brands available? Websites?
TIA
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I have a JB's guppy tank and I am very happy with it. Perfect for a day in the field for me. But then you have to fill it quite frequently. I don't like to see my shoebox working so hard every week. I read somewhere that a 44 cf tank is a good compromise between portability and number of fills. Does anyone knows the dimensions and weight of a 44 cf tank? Brands available? Websites?
TIA
I bought a 30 minute SCBA tank (45CF) as a portable fill station.... the cylinder itself is a little over 10lbs not including the filling hardware. I would not consider it a viable option for backpacking. The 75CF tank is only slightly heavier, very close in length, and fatter-- but way more fills. Something about how volume increases much faster than surface area. I think the ideal setup (for my purposes anyway) is one small 90CI tank and a bigger 75 CF or bigger.
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The Joe B math used to arrive at 97 cu ft for the tanks he sells is *WRONG*. They are 550 ci internal volume, and since air gets less compressible after about 3000 psi, they only hold 88 cu ft...which is ov course what the SCBA companies that actually make them rate them at.
The JOE B 550 ci tanks used to carry the 88 cu ft rating, but since bigger is better, he mis-applied ideal gas law to get the 97 cu ft number. Is a big heap o' steaming marketing...why y'all tolerate it is just beyond me.
cheers,
Douglas
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I've got one of Joe B's Guppy tanks and it's a nice piece. I'm filling it with nitrogen. I also bought the nitrogen set up from Joe. I went with the Guppy to start with for portability and also money at the time. If I determine that I need more tank capacity, I will probably get a GW from Joe.
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Lets see.....gym membership......and bottle fed airguns.....with a pump in the closet collecting dust. How does that make any sense at all? ::)
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Lets see.....gym membership......and bottle fed airguns.....with a pump in the closet collecting dust. How does that make any sense at all? ::)
Unless your biological clock is still on the AM not the PM side of the equation it is important to remember that us old folks would rather shoot than pump and when I want to sweat I jump on my bicycle or into my ocean kayak and enjoy the view while I sweat ;D ;D ;D just saying but all kidding aside the 0 to 200 psi when the seal finally started to hold pressure was a serious workout maybe 100 strokes with the Hill boosted to 25 psi
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Does Joe B. answer his email (info@airtanksforsale.com)? I've sent two inquiring about prices and no response.
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best way is to call him and talk
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Good luck E Mailing him as he does not reply 80% of the time and when he does it is several days to a week later.
Norm
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Joe B's tanks are the exact same size as everyone else's. They are not larger. I would opt for the Airhog or give Tim a call. Also check ebay for used tanks.
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I just got a great white and I love it. I lose less air when I bleed off from filling. It is a much nicer set up from my Ninja which I now use tethered on my Talon Pistol. On a side note I have had mine for a week and Joe did not charge my credit card. I called today and told him. He thanked me for my honesty and told me my next purchase of a tank will be $100 off. I am proud to say honesty does pay off. Maybe I will take him up on the offer for a Freedom 8, but to tell you the truth a Condor .25 24" barrel is looking better to me.
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All this Joe B slamming sure gets OLD !!
As with anyone in retail your going to have followers and haters ... get over it if you feel his advertizing practices are shady !
His Products and support stand independent of that fact.
Want a Ford, buy one ... Chevy or a Dodge, that's OK too 8)
As for the NINJA ... after @ 9 months ownership of the small 90cu with integral regulator ... I'M SO DONE with it !!
Blown 5 burst disks with ALL being during fills or storage with ALL FAILING under the 4.5 fill rating. (http://www.bmwlt.com/forums/images/smilies/thatswack.gif)
Retrofitted the entire valve, gauges & hose with one of Joe B's conversions for the PB bottles ... SOOOOO much better ;D
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As with anything you buy, you get what you pay for. Joe's product are expensive but they are top of the line and he stands behind what he sells.
Joe is not very good with E Mails but using the phone always works.
Love my Guppy!
Norm
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All this Joe B slamming sure gets OLD !!
As with anyone in retail your going to have followers and haters ... get over it if you feel his advertizing practices are shady !
His Products and support stand independent of that fact.
Want a Ford, buy one ... Chevy or a Dodge, that's OK too 8)
As for the NINJA ... after @ 9 months ownership of the small 90cu with integral regulator ... I'M SO DONE with it !!
Blown 5 burst disks with ALL being during fills or storage with ALL FAILING under the 4.5 fill rating. (http://www.bmwlt.com/forums/images/smilies/thatswack.gif)
Retrofitted the entire valve, gauges & hose with one of Joe B's conversions for the PB bottles ... SOOOOO much better ;D
I agree. Getting old. I went with JB and everything is first class and no problems at all. He was great talking to for info and everything was on it's way, post haste ! Many times, a buck or two more is the better way to go.
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I need a tank also. How do I get hold of this joe feller? Or find out about his tanks? Does he have a website?
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www.airtanksforsale.com (http://www.airtanksforsale.com)
best way is to check his site to see what you want,and then CALL him :)
714-907-0067
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http://www.airtanksforsale.com/ (http://www.airtanksforsale.com/)
714-907-0067
I drive through Madisonville often, we could meet a Buckees. :)
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;D I bought 2 Guppies from Joe and the tank Gauge was leaking at the threads and when I told him what had occurred his response was whatever it takes to make it right . Being an HVAC mechanic rather than send back I removed the Gauge and resealed the threads the entire set up is top shelf and It was just easier for me to break out a 7/16 wrench and black Rector Seal thread compound . 10 minutes and all better
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All this Joe B slamming sure gets OLD !!
As with anyone in retail your going to have followers and haters ... get over it if you feel his advertizing practices are shady !
His Products and support stand independent of that fact.
Ahhh...no it does not.
I'll bet you I can find more than a few folks who bought the tank labeled 97 cu ft because it was claimed to be bigger. I will further bet that I can find folks who also discovered that this tank is really nothing but an 88.
Saying, 'I'll change to a real rating if AoA does' is...errrr....poor behaviour IMO, and certainly worthy of avoidance. Deal with folks who deal honestly.
AoA is claimed by Joe to slightly further misrepresent a 66/45 mins tank as being capable of holding 75 cu ft. No surprise there...they still have not admitted to changing the rules on the Extreme FX Pellet Gun Demo.
cheers,
Douglas
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All this Joe B slamming sure gets OLD !!
As with anyone in retail your going to have followers and haters ... get over it if you feel his advertizing practices are shady !
His Products and support stand independent of that fact.
Ahhh...no it does not.
I'll bet you I can find more than a few folks who bought the tank labeled 97 cu ft because it was claimed to be bigger. I will further bet that I can find folks who also discovered that this tank is really nothing but an 88.
Saying, 'I'll change to a real rating if AoA does' is...errrr....poor behaviour IMO, and certainly worthy of avoidance. Deal with folks who deal honestly.
AoA is claimed by Joe to slightly further misrepresent a 66/45 mins tank as being capable of holding 75 cu ft. No surprise there...they still have not admitted to changing the rules on the Extreme FX Pellet Gun Demo.
cheers,
Douglas
I am very happy with Joe. He told me straight up his tanks were the same as an 88. I found his product to be much better than Ninja tank as well. In life what goes around comes around. Do good and good comes back, do bad and watch out!
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I am not bashing anyone. Just pointing out a fact. That fact is I purchased one of his tanks new. I was one of those who was stupidly dupped by his advertising. I also own 3 other brands of tanks ( yes I own 4 tanks ) Mac1, Airhog and Dragger. All of them are of the same quality and work just as well. My advice is go with the one that fits your budget, and don't be mislead in to thinking your getting a larger tank from joe. They are all 88 cubic foot tanks..
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I do have a question. I could ask the vendors, but we have an informed group here. which is bigger the Ninja or the Guppy? I do like the valves and gages on the GW compared to the little Ninja.
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Joe is a callous guy, just spend a few minuets speaking with him and it becomes quite obvious he feels strong in his convictions & opinion.
Yet at the same time speaks about as matter of fact as one could wish for.
As the world turns , love or hate separates the world order .... If you feel your right and another wrong you simply have that freedom to not deal with that person.
When speaking of broader perspectives and product that has none of the He said / She said BS attached the buck stops !!
Love it or leave it letting each who chooses to read others accounts good bad or otherwise stand as opinion.
The constant jab by the few at someone whom is causing NO safety or Liability issues while providing a great product at a good price needs to stop !!
You haters have voiced your opinion ... GOOGLE IT, it's noted !!
Time to not so good it up and get off the soap box of hate rants.
(http://www.bmwlt.com/forums/images/smilies/soapbox.gif)
Scott
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I got my tank used from Mac-1.
fully tested and certified... saved me considerable money... and I'm quite happy with it.
Tim occasionally has them in stock, even though they may not be on the website.
Best to call and ask.
http://www.mac1airgunshop.com/co2-hpa-parts-s/1837.htm?searching=Y&sort=2&cat=1837&show=10&page=1 (http://www.mac1airgunshop.com/co2-hpa-parts-s/1837.htm?searching=Y&sort=2&cat=1837&show=10&page=1)
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Joe is a callous guy, just spend a few minuets speaking with him and it becomes quite obvious he feels strong in his convictions & opinion.
Yet at the same time speaks about as matter of fact as one could wish for.
As the world turns , love or hate separates the world order .... If you feel your right and another wrong you simply have that freedom to not deal with that person.
When speaking of broader perspectives and product that has none of the He said / She said BS attached the buck stops !!
Love it or leave it letting each who chooses to read others accounts good bad or otherwise stand as opinion.
The constant jab by the few at someone whom is causing NO safety or Liability issues while providing a great product at a good price needs to stop !!
You haters have voiced your opinion ... GOOGLE IT, it's noted !!
Time to not so good it up and get off the soap box of hate rants.
(http://www.bmwlt.com/forums/images/smilies/soapbox.gif)
Scott
Finally the voice of reason thanks Scott you da man ;D
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Not sure I understand those telling people to stop stating 88 ≠ 97 ? Everyone is entitled to their opinion, but this goes beyond that. 88 ≠ 97. That's not opinion, that is reality. I have no doubt Joe's regulators and valves are top notch, and he is matter of fact, being an engineer and all, but people are allowed to state their opinions on someone's marketing. I don't want my info sugar coated, I want to be able to weigh the good and bad in order to make an informed decision.
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You haters have voiced your opinion ... GOOGLE IT, it's noted !!
Time to not so good it up and get off the soap box of hate rants.
(http://www.bmwlt.com/forums/images/smilies/soapbox.gif)
Scott
You accuse me of hating Joe, with proof of this accusation being I call attention to deliberately misleading advertising. I don't know Joe, and therefore don't hate *OR* like him. Your labeling folks who call this stuff into the open as 'haters' is just downright nasty in and of itself.
I suspect the complaints about this advertising will go away when the advertising itself goes away. The 97 label is wrong. Air is not ideal and does not obey the Ideal Gas Law at the pressure those tanks are being filled to. Why is it that for saying this, I am a 'hater'?
cheers,
Douglas
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You haters have voiced your opinion ... GOOGLE IT, it's noted !!
Time to not so good it up and get off the soap box of hate rants.
(http://www.bmwlt.com/forums/images/smilies/soapbox.gif)
Scott
You accuse me of hating Joe, with proof of this accusation being I call attention to deliberately misleading advertising. I don't know Joe, and therefore don't hate *OR* like him. Your labeling folks who call this stuff into the open as 'haters' is just downright nasty in and of itself.
I suspect the complaints about this advertising will go away when the advertising itself goes away. The 97 label is wrong. Air is not ideal and does not obey the Ideal Gas Law at the pressure those tanks are being filled to. Why is it that for saying this, I am a 'hater'?
cheers,
Douglas
Now I am confused, If you call out Joe for his calculations being misleading:
AirTanksForSale 550 Cu In x 4500 / 14.7 /12/ 12/12 =97.43 Cu Ft. I round down to 97 Cu Ft.
Why do you not call out Air Guns of Arizona for the same thing:
Airguns of Arizona 417 Cu In x 4500 / 14.7 /12/ 12/12 =73.87 Cu Ft. They round up to 75 Cu Ft
Or is there another agenda going on here (one being a contributor and the other is not)? How do we pick and choose on who to crucify on the cross? I am not going to cast the first stone, but at the same time my morals will not let me stand by and say nothing. What is right is right and what is wrong is wrong, they are either both right or they are both wrong. Joe & AOA are either both misleading us or they truly believe that their calculations are true and correct.
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I'm perfectly happy with my purchase. I went with what suited my needs and what I wanted to spend. Everything works as it should.
But .... just for the heck of it. Vendor X's tank is 88 and vendor Y's is 97. If Vendor Y's tank is really 88, how many fills in a Marauder 3000 to say 2000 psi have you lost out on :). Is all this really that big of a deal ?
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I'm perfectly happy with my purchase. I went with what suited my needs and what I wanted to spend. Everything works as it should.
But .... just for the heck of it. Vendor X's tank is 88 and vendor Y's is 97. If Vendor Y's tank is really 88, how many fills in a Marauder 3000 to say 2000 psi have you lost out on :). Is all this really that big of a deal ?
If it's not that big of a deal why would vendor Y lie about it? Is it 88 or 97? Just be honest. Not hard really.
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Other than the old false advertising issue, if the alleged 97CF tank costs more than the 88CF tank, then there is a problem.
I have not looked at pricing on the 4500psi tanks as they are more than I am willing to spend so I don't know if they are selling for more than the others.
False advertising does not instill confidence in me with the merchant(s) doing it
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I spose everyone has their points and opinions. For me, being a fill station newb, I liked the one stop shopping with someone who would know exactly what parts and pieces would work together for what I wanted to do. Sure, I probably could have saved a buck here and there, but the chance of getting a wrong piece to the puzzle and doing returns or buying replacement parts wasn't something I wanted to deal with. Been there, done that with other things.
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I spose everyone has their points and opinions. For me, being a fill station newb, I liked the one stop shopping with someone who would know exactly what parts and pieces would work together for what I wanted to do. Sure, I probably could have saved a buck here and there, but the chance of getting a wrong piece to the puzzle and doing returns or buying replacement parts wasn't something I wanted to deal with. Been there, done that with other things.
Yep, This thread is the first time I've heard anything bad about Joe. I agree the one stop shopping with knowledge is a great convenience, and where it seems he has carved his niche. The possible incongruence on his tank size listings is concerning, but not a deal breaker IMO. Seems an easy issue for him to remedy.
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;D At the end of the day as long as the tanks hold air at pressure and the accessories do the same the way I see it is if they all hold the same amount and the Ivory tower folks have pointed out the math errors or incorrect advertising for the world to see the rest is up to the buyer to follow the path they choose to purchase the product. Since becoming a member last year I have seen just about every product purchased by myself bashed or knocked by others on this forum, and at the end of the day the final decision was mine. Two very fine AG's that I purchased did not end up pleasing me in one way or another and have already been sold or will be sold. That is also MY choice, the threads are informative and serve to help me decide the choices made. So I guess what I am saying in a very long winded fashion is liking or disliking a particular product bases on no personal hands on remains opinion and will remain just that "OPINION" . Once the opinion is based on hands on experience it becomes reality ::) ::) :o
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. Once the opinion is based on hands on experience it becomes reality.
[Pedant mode] An opinion no matter what it is based on, is still opinion. :) [/pedant mode]
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. Once the opinion is based on hands on experience it becomes reality.
[Pedant mode] An opinion no matter what it is based on, is still opinion. :) [/pedant mode]
;D I stand corrected so lets say it becomes an informed and knowledge based opinion ;)
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Now I am confused, If you call out Joe for his calculations being misleading:
AirTanksForSale 550 Cu In x 4500 / 14.7 /12/ 12/12 =97.43 Cu Ft. I round down to 97 Cu Ft.
Why do you not call out Air Guns of Arizona for the same thing:
Airguns of Arizona 417 Cu In x 4500 / 14.7 /12/ 12/12 =73.87 Cu Ft. They round up to 75 Cu Ft
I have, and by those numbers you posted clearly show AoA is doing the exact same thing. The AoA tank in fact being a 45 mins/66 cu ft tank misrepresented by a mis-use of Ideal Gas Law.
Go on, support dealers who misrepresent their wares...it hurts all of us.
cheers,
Douglas
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;D I stand corrected so lets say it becomes an informed and knowledge based opinion ;)
There is no like button, so please accept this smiley. :)
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Now I am confused, If you call out Joe for his calculations being misleading:
AirTanksForSale 550 Cu In x 4500 / 14.7 /12/ 12/12 =97.43 Cu Ft. I round down to 97 Cu Ft.
Why do you not call out Air Guns of Arizona for the same thing:
Airguns of Arizona 417 Cu In x 4500 / 14.7 /12/ 12/12 =73.87 Cu Ft. They round up to 75 Cu Ft
I have, and by those numbers you posted clearly show AoA is doing the exact same thing. The AoA tank in fact being a 45 mins/66 cu ft tank misrepresented by a mis-use of Ideal Gas Law.
Go on, support dealers who misrepresent their wares...it hurts all of us.
cheers,
Douglas
Oh great... I didn't know about AoA. Until it was mentioned in this thread I had thought the AoA Omega tank I bought was 75CuFt.
NOW it makes sense why it didn't seem much bigger than the 30minute SCBA tank I bought off eBay. I looked it up and 30 minute tank = 45 CuFt. I had figured it would be a lot smaller than a 75CuFt tank. It wasn't that much smaller and now I know it is because the AoA tank is 66CuFt and not 75 Cu ft!
I had the SCBA tank hydrotested and resold. Didn't take a loss, but it was a hassle. I'm new to PCP and count me as one of the people who doesn't like these calculations. Fool me once....
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Go on, support dealers who misrepresent their wares...it hurts all of us.
cheers,
Douglas
Hurt ??? ???
One's EGO is about it on that one ... makes little difference what side of this debate you side with. Issue here is that of differing opinion and that POLL of others thoughts on said formulas in question fueling a debate fire.
No safety ... Liability or HURT issues to anyone happening here !!!
You would think such a heated debate as this would be viewed as POLITICS ... which clearly it is not far off from :P
What this boils down too is Public Internet assassination of another persons view point and convictions of standing there ground who differ from others.
Don't mistake this as a Pointing of fingers from any side of this ongoing fight ... Got no dog in this fight, but do as a Member at large get darn annoyed with the bickering and finger pointing from both sides near every time such threads get posted.
I'm done :-X
*Spell correction made
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The one thing you all forget is.... somebody else builds the tanks for each company and stamps that companies name on them, so if you shop around as far as tanks are concerned a 4500 PSI tank is just as good as the other guys! Fill Stations are generally made the same way! Well besides the point, my air venturi tank (90 CI) with fill station and regulated valve included from Pyramyd Air gets me about 12 fills on my Marauder and 2x that many on my Discovery. I have had no problems with my Air venturi tank or valve at all works great and very portable. I would rather drive 100 miles for a little bit of air than stand around pumping the stupid pump all day, especially on a Marauder at 3000 PSI. I want to enjoy shooting not die of exhaustion! lol
Link to a good tank and well worth the investment...
https://www.pyramydair.com/product/air-venturi-carbon-fiber-air-tank-fill-station-4500-psi-88-cu-in?a=4708
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Go on, support dealers who misrepresent their wares...it hurts all of us.
cheers,
Douglas
Hurt ??? ???
included on edit:
What this boils down too is Public Internet assassination of another persons view point and convictions of standing there ground who differ from others.
Yes, hurt...how much trouble are you going to have to put forth to make sure you are getting what you think you're getting? Are you capable of making the effort? This is one more brick in the wall that keeps me from knowing what I am buying...support the vendors that are doing it and it gets worse.
Fortunately, in this particular case I have an adequate education in physical law that allows me to spot this particular mistake relatively easily. For telling y'all about I get labeled a 'hater', and 'public internet assassin'.
You can differ all you want, in this particular case, it is not about 'differ-ing', air is *NOT* an ideal gas, and treating it as such is entirely wrong. With extreme sarcasm, I say, 'I wait for somebody to differ with me on saying the sun does not shine during the day'. Behaviour of compressed gases is not a newly emerging science, try looking up 'non-Ideal behavior of compressed air' and see what you find.
It is not 'public internet assassination' either. Anybody who has made such claims is wrong, and in at least one of the cases, adequate evidence of their mistake has been provided...and the justification given was, 'somebody else does it'.
cheers,
Douglas
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Hopefully I can clear up this mess about 88 CF tanks being called 97 CF.... Until very recently, I too was miscalculating the volume of air in 4500 psi tanks by using Boyle's Law.... Using that, you do indeed get 97 CF for the volume of air inside a 550 CI tank at 4500 psi.... However, Boyle's Law, while almost 100% correct at 3000 psi, doesn't give the correct answer at 4500 psi, because air doesn't perform as an "ideal gas" as Boyle's Law would predict.... This increases the pressure more quickly than it should according to Boyle when the tank is filled beyond 3000 psi.... Here is a diagram which should help you to understand.... Check out the line for Nitrogen (N2), which is 80% of air.... This diagram is based on the Van Der Waal's equations, which correct for this factor....
[img width= height=]http://www.chem.ufl.edu/~itl/2045/matter/FG10_020.GIF[/img]
Note the value of the mulitplier on the left axis, which is 1.0 at 204 atm. (3000 psi), but is about 1.13 at 310 bar (4500 psi).... What that means is that the pressure at 306 atm. is about 13% higher than if Nitrogen behaved as an "ideal gas", which is what Boyle's Law assumes.... So, for our example, while at 3000 psi, that 550 CI tank would contain 550 x 204 / 1728 = 65 CF, and at 4500 psi (by Boyle's Law) it should contain 550 x 306 / 1728 = 97 CF.... you actually have to divide that 97 CF by 1.13 to get 86 CF.... The difference between that 86 CF for Nitrogen and the 88 CF for air is because of the Oxgen content, which follows a similar, but slightly different curve to the Nitrogen....
So, if you use Boyle's Law (which is inaccurate at 4500 psi) you get 97 CF.... If you correct it to allow for the non-ideal behaviour of air at 4500 psi (which is the correct calculation), then you get 88 CF.... I didn't understand this until very recently, and I thank Pak Protector, and Steve in NC, for clarifying it for me.... The bottom line is, that at 4500 psi, the 550 CI tanks contain 88 CF of air, not 97 CF....
Bob
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For telling y'all about I get labeled a 'hater'.
cheers,
Douglas
People have a hard time accepting that they might have been fooled, and find it easier to attack the messenger than to accept the possibility they were.
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Gentlemen, this thread has gone far enough off the original track. Hurt feelings and angry responses have no place on the GTA. It's time to step away from the calculators and get back to shooting air guns. Carry on, gentlemen!
Joe