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Discussion Starter · #21 ·
OMG NECRO POSTER!! KICK HIS ASS!!!

Nope not this time! I added more important info!

Well I finally got around to updating this, and glad I waited. Lots of stuff has come out sense I wrote this and it seems HPA rifles are becoming more popular. Yes I know some of the numbers in the first post are off. I'll update those in a bit.

Right now I have about 6 firefox windows open with about 50 or 60 tabs on each. I have started loosing track of what is what. I will finish it up at some point this week hopefully. Right now I am on break. Here is the link to the updated post.

http://www.airsoftsniperforum.com/3...rsoft-gases-external-gas-rigs.html#post102175
 

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Discussion Starter · #22 ·
Well, I am sure most of you know you just can not fill an HPA tank off a home compressor...

This is a very accurate statement, like all things it has an exception. This is that exception. (or device similar to it)

Home << ShoeBox Compressors - The World's Smallest & Lightest 4500 PSI Compressor

I know it says "compressor" in it, and it is a compressor, and at the same time it is not.
This is a 2nd stage booster. It takes the 85psi input from your home OIL-LESS compressor and boosts it up to 3000-4500. (model dependent)

With a price tag of $700 USD for the base model and $1150 for the Freedom8, it's an option for those who do not have fast access to HPA filling capabilities. Speaking of speed, this thing lacks it big time in the time to fill department. The time it takes to fill a 68/4500 tank, take roughly 2 hours, and for a 88/4500, 4.4 hours. (used the math formula here: Performance | Typical Fill Times << ShoeBox Compressors - The World's Smallest & Lightest 4500 PSI Compressor using the Freedom8)
 

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Can't we use a $100 air compressor as long as it has the right fitting? I was hunting at my grandmas this past weekend and she has a 10-15 year old air compressor we fill our ATV Tires with. It has my HPA hoses fitting, but it's like one size bigger. Could I have filled my tank w/ a smaller size?
 

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The issue is one of pressure. A $100 air compressor might yield 120PSI if you push it. Some more expensive home compressors can reach 150PSI. The professional grade Ingersol-Rand I had in my old hot rod shop only went up to 175PSI.

HPA tanks are usually pressurized to 3000PSI or 4500PSI.

Home units can not cut it.
 

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Problem solved guys. Get one of these instead and get fit.
High Pressure Airgun PCP Hand Pump 3300psi 4500psi 3 Stage Venturi G4 HPA Hose with 1/8" BSPP Threads Air Rifle-in Pumps from Industry & Business on Aliexpress.com | Alibaba Group
They are a lot of work to fill up a 48ci bottle but at least it is free. A 48oz bottle will take about 300 pumps to fill. The longer you pump the harder it gets. There is a youtube video somewhere with a guy who fills one. He looks stuffed afterwards but it was free air.
 

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This might make me consider buying HPA... Needing to find a supplier of scuba tanks/refill stations and drive out to them sounded like too much trouble. We all breathe air constantly, and no one should charge us money to put it into a big bottle* :p

*Except for that initial $104.99 DISCOUNTED price...
 

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Discussion Starter · #28 ·

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Discussion Starter · #30 ·
High pressure low volume is essentially using a small amount of air at a high pressure. Pretty much what you normally see in airsoft. Low Pressure High Volume is what you see in polarstars and the like.

As for what goes on in the barrel is hard to say, as the people who claim to know refuse to post up the data. I honestly don't know.

My best guess is that with HPLV it can possible lead to the bb bouncing around the barrel due to the high pressure, but the low volume would mean that you are relying on getting the bb out of your barrel by force of the air pressure . While LPHV should not bounce the BB around as much, due to the lesser force used, and with the large amount of air behind it it should be more stable.

Again, that is theory.
 

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Discussion Starter · #31 · (Edited)
I just had my tanks Hydrotested and I am going to post pics showing what to expect from it.





First up is my Fiber Wrapped tank.

Now the Aluminum tank.
 

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As for the high pressure/low pressure debate

Remember that gas wants to equalize with the atmosphere, a higher pressure gas is going to expand faster when its higher pressure, and then slower as it starts to equalize (eventually reaching zero)
this means that acceleration is going to be back-ended mostly, the trick to running high pressure is you dont want the initial burst of pressure to be too small, so that the bb outruns the expanding gas (not likely, but it can happen) since you're using more of the gas's power band, its more effective per-CU of gas

lower pressure is going to give you more consistent acceleration throughout barrel travel, but because its going to equalize slower, you need to use a lot more CU of gas to keep the BB from outrunning the gas, because of how hopup works, lower pressure tends to be less accurate and/or require a lot more hop because the bb isn't getting much energy imparted to it as it passes through the hop

we really don't travel too far in pressure higher or lower in airsoft, for airguns you see up to 1000+psi being fired, in airsoft its like 80-120psi is the difference between high and low pressure, so the effect isn't very noticeable.
 

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Discussion Starter · #34 ·
Gas source cleanliness

Something I have failed to talk about is how clean your source gas is. Actually I apparently did a very small amount...

This is something you can not really control, but you can take into consideration when filling/buying your gas. This is mostly for HPA and CO2, but I would imagine that it is the same for others as well to some extent.

Take this with a fair amount of marketing wank, How to Pick Good Quality CO2 for Your Airgun

Yes, different brands have different levels of cleanliness to them. This grossness will eventually make its way into your gun. (depends on the brand and contaminant) You will need to clean your gun out sooner or later. Same with your regulators. If you are super active and shooting a lot then you will want to clean your gun a little more often then the guy who goes maybe once a month.
 

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Discussion Starter · #35 · (Edited)
Speaking of CO2... Lets talk about something that not a lot of you may know about!

That being the Piercing Pin/Valve. There are a lot of different designs to do the same thing. Over time yours will deform and perform worse and worse. This is just how it goes, it is a sacrificial part.

Unfortunately it can be difficult to find replacements. I think Palmer's has them, you need to call them for them I believe as all they have on the site is the seal ring. (Also important as those fail before the pin does, or falls off and gets lost.)

I have found a few places that sell them, but most are all the same. This one is different...

https://samoon.com.tw/co2-pierce-v1?search=piercing%20tool

I am going to order a few and test them out. If they perform as advertised then this would be a welcomed upgrade over the ones I currently have installed in a few of my other guns.

Or not... $27 in shipping... ridiculous.
 
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Discussion Starter · #36 ·
So... this happens.


This is a real danger for those in areas with hot weather or if you stage out of your car. Do not leave your gas in high heat environments. Yes, this includes your HPA bottles, and CO2. Your green gas/red gas/any other gas that use the same style bottle, lack the safety blow offs like your HPA tanks and paintball co2 tanks have. (Burst disks...)

People make fun of me for storing my gas, bbs, and batteries in a (highly) modified ice chest that has a large steel ammo box bolted into it... I am sure people will quickly stop laughing and realize the genius of my crazy box after something like that happens to them or around them.

That reminds me.... I really should look into building the mk2 box...
 

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This happened a while ago actually. I read that it was because of the new bottles that nuprol designed that were not a one-piece design.

Still, obviously, don't store gas bottles in a hot place, especially not in a car... Bodge learned that the hard way :doh:
 

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Discussion Starter · #38 ·
Unfortunately he did learn the hard way.

I will agree that the bottle design is pretty bad. The price of cost savings is evident as all hell on that one.
 

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Well, since I was somehow directed here.. I gotta say you gotta it all wrong.

Propylene has more pressure than propane. That means, Map Pro (yellow cans) can withstand lower temperatures than Propane (blue cans) / green gas.

I'll leave some links to technical vapour pressure charts about the three main gases for airsoft:

HFC-13A - Propane - Proplylene

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"Green gas" airsoft guns are designed to operate about 80 to 170 PSI range. That means:

* about 25ºC to unrealisticly hot 50ºC for 134A
* 12ºC to 37ºC for propane / green gas
* 4ºC to 29ºC for propylene.

The lower you go on the temperature range for a given gas, the more volume it will take for each shot, and thus, the least gas millage. Theoretically, in a perfectly sealing gun you can go even lower, as far as the pressure is enough to overcome the atmospheric pressure (about 14PSI) + the strenght of the springs. I've used Propylene at -2ºC (65PSI) on a WE AK without major issues other than high gas consumption, and that thing has a heavy bolt, strong recoil spring and perhaps the longest bolt travel distance in all airsoft.

Going higher than that range can and will produce damage to the seals in most guns, perhaps the only notable exception being the GHK M4 mags. Those beast can handle injected CO2, which is insanely hot.

BTW, never, ever, ever try to inject CO2 in green gas mags (unless it's GHK M4 with DevilHunter's mod). CO2 has at least 5 times the pressure the mags are designed for, and the mags will bloat and fail beyond any possible repair. Sounds like an abvious advice, but as a GBB tech I've received many, many mags on the "I don't know why, it keeps leaking" excuse, only to later find out they have injected CO2 and the metal walls of the mags are literally bloated.

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Plastic slides guns such as some KSC and Marui work at lower pressures as they have to defeat way less weight, so 60 to 100 PSI is normally more than enough.

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As for red gas, black gas and such designations, cannot provide specific data unless someone knows the real gas composition (as in "green gas is propane")

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Going into experimental territory, for those cold times when not even Propylene is enough, the newest kid in the block of refrigerant gases shows great potential.

The theoretical range for R32 in a "green gas" mag would be -8ºC to 14ºC, so it should work perfectly for those scenarios on which people normally would go for CO2 mags.

So if anyone feels like trying their chances.... I would do that myself, but R32 is not yet available in my country. That's a first world kind of thing :p

-------

As for the flammability discussion, all refrigerants are either flammable, toxic, global warmers or ozone depleters. So really, flammability doesn't sound that bad.
 

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Discussion Starter · #40 · (Edited)
Oh? So I got it wrong? Huh... Well lets test something.

70F is 21.1111C(repeating), For proplylene 21.111 is not on there so you have to look at 2 numbers 20 and 22. Which are 132.78 psig and 140.53 psig. So with that said, and I realize that I failed to post the measures in my OP, however, if you take the 133psi I claimed for proplylene. Funny that it coincides with your chart.

So, for 134a, the 100psi I said is for my normal temperature of 90F+ or 32.2C so looking at your chart for that, that would be 103.55. Little off, but not enough for me to say wrong, as 30C is 96.99. Though I should have been clear on that. (Ill fix it in a bit.) Same with propane. So, no I am not wrong, I just failed to list temperatures for the given psi.

Which I have fixed.
 
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