Propane Adaptor - ASR Airsoft Reviews

Author

TehLlama
MacGyver

Registered: May 2004
Location: Albuquerque, NM, USA
Posts: 9759

Review Date: Mon April 10, 2006

Would you recommend the product? Yes | Price you paid?: $29.00 | Rating: 9

Positive aspects of the product (pros):	Cost savings, Excellent for gas sniper rifles
Cons:	Initial cost, SMELL

First, a disclaimer: This review and article deals in part with the chemical composition of gases. I am not a chemist. My fields of study are computer science and 20th century geopolitics, with a fair understanding of Newtonian mechanics. However, I did take a bit of chemistry in high school, which is hazy enough to be only partially useful, and I worked at the nanotech lab at the University of Texas at Dallas this summer, where I brushed up on the elementary basics of organic chemistry, which are unrelated enough to be mostly irrelevant. However, I should be as qualified to judge the data presented as the typical airsoft player, and vice-versa. I can give my view of presented conclusions, but you should also make your own decisions. That is, tread carefully since the article deals with some ideas fairly radically new to the mainstream.
-Shane "Supergeek" Lin

http://www.airsoftretreat.com/gallery/data/561/medium/AIPA_1.JPG

Of the three general types of airsoft guns, those that are powered by gas clearly produce the best sense of realism. The operation of the cycling bolt or slide cannot be easily replicated by either an electric motor or a manually compressed spring. That is, it is difficult to generate the requisite torque with a small enough motor and battery and using a spring to cycle itself sort of violates the laws of thermodynamics. However, also unlike electric and spring, renewable respectively through rechargeable batteries and the human consumption of food, gas guns must be satiated by a continuous supply of airsoft gas. For the modern GBB, this typically means made-for-airsoft HFC134 or green gas. Although PC Duster gas can be substituted for HFC134, the jury-rigging required to create a viable nozzle makes the process less than healthy for fill valve o-rings. Thus, the discovery of a very low-cost, high availability gas would certainly be a sort of airsoft holy grail.
It was some weeks ago when my boss, Big Aaron Benzick, dropped off a production model of an adapter nozzle for small propane tanks made by the newly start-up Airsoft Innovations. The use of propane to cycle gas blow-back pistols as an alternative to Green Gas is not unprecedented. In fact, some players have been reportedly using it for years with success. However, it has never quite hit mainstream, being relegated to the experimental fringe with other gases (like Butane, which can be habit-forming and cause serious health issues if inhaled). This is the first commercial product to my knowledge which adapts propane for airsoft purposes.

Cost Benefits

Propane is highly economical as an airsoft gas. I picked up a small can of Coleman Propane Fuel, probably designed for gas lamps and small cooking grills, from the local Target for around $2.50. The net mass is 465g, so given a density of around 583.074kg/m^3, the can contains about 7.97x10^-4 cubic meters of propane. So, the cost if $2.50 for just under 800ml of airsoft gas, which makes propane about 3 times less expensive than the cheapest airsoft green gas I could find in the United States. And you don’t even have to have it shipped to you. Apparently, in Canada, obtaining green gas is much more expensive than in the US, which would mean an even greater ratio.
So, for the average US airsoft player, the best price for a 1 liter can of green gas will probably be around $9-$12 with shipping. The Airsoft Innovations adapter nozzle is being sold for $30 USD shipped. Propane is around $2.50 for a 800ml can. Throw in $3 for a bottle of silicone oil, which will need to be added to the magazine before using propane. Which means (and I’ve done the math for you here already), the adapter covers its own cost after 6 cans of green gas, assuming the cost of $9. I’ve certainly used more than that in the past few months.

The Adapter Nozzle

http://www.airsoftretreat.com/gallery/data/561/AIPA_2.JPG

I am really fairly impressed by the unit itself. It is made of very nicely machined brass and is composed of four pieces. There is a large threaded fitting that screws onto the propane tank, a washer and spring which go into the fitting, and the nozzle, which is inserted last. The four-piece design seems to be to ensure the widest compatibility with various propane tanks, as well as to allow easy removal of just the nozzle to ensure safe transport.
Installation is completely inconsequential. A very smart monkey could assemble it in around 15 seconds. Since it may equivalently take the average airsoft player upwards of a minute to figure it out, I’ve included a quick video demonstration, omitting only the step about placing a drop of silicone oil on the nozzle (I’d just done that right before), Check the media section at the bottom for the video.
Along with the nozzle, I received a very nicely illustrated manual documenting installation and use, as well as some hazards and precautions. And a stereotypical Asian woman without a nose. But, being a fellow Mongoloid (big M, not small), I wholeheartedly approve. In fact, the illustrations are very good, and the whole production is really much better than I could have expected from something like this (especially after wading through all those little colored paper strips that come with Japanese aftermarket accessories and upgrade parts).
The nozzle seems to provide as good of a fit as any green gas bottle when it comes to filling. I don’t have a KJW or HFC magazine on hand to really test it, but I’m sure that it’ll achieve the same no-leak seal with those guns as the typical green gas bottle. Oh the whole, it offers a much less leaking than hand-cut plastic nozzle adapters using duster gas. It is also long enough to reach into the fill valve inside the bumper pad of my Western Arms V12, a gun which has had problems fitting various other gas bottles in the past.

http://www.airsoftretreat.com/gallery/data/561/AIPA_3.JPG

Green gas = Propane? That’s crazy talk!

Carlton Chong, the Canadian mechanical engineer behind Airsoft Innovations, goes further to claim that at the least many brands of green gas often used for airsoft purposes are actually just propane. While this may at first seem incongruous with everything which you’ve been told about green gas, with some thought it makes a lot of sense. I have a bottle of green gas here. It is the green-and-white camo pattern kind marked “Green Gas - Super Power” which is very common in the United States. On it is a label declaring that its chemical composition is CH2 FCF3 CH3, which is also listed as the chemical composition for other brands. This sounds reasonable, as the less mysterious HFC-134 and Propane gases are well documented (because of their refrigeration and cooking utility) and are composed of, respectively, CHF2CHF2 and C3H8. Clearly, CH2 FCF3 CH3 (green gas) is not equivalent to C3H8 (propane).
What’s wrong here, then? As Carlton points out, CH2FCF3CH3 doesn’t actually exist (for a marketable amount of time, at least). And he’s right. Under octet rule, such a molecule would be unstable because carbon does not have enough bond sites for all the Hydrogen and Fluorine. Even with my lack of education in deeper matters, this much is certainly crystal clear.
So, I corresponded with Carlton to find out the specifics of his tests. It would seem that he’s been quite thorough. He writes of conducting three tests himself with Coleman propane and at least three types of green gas: Jet Gas, “Shooting Air” and “Green Power”. He compared the flames of the various green gases with the propane and tested for pressure at various temperatures and the density at room temperature. All tests were successful to degrees of relative certainty. Let’s take a look at the tests. The flame test is a good test for exclusion since some gases produce vastly contrasting flame colors. That the flames were similar is not an indication that the tested gases are the same, since dissimilar gases can also produce comparable flame colors. There’s a video of this test on the Airsoft Innovations article on his tests – it’s pretty darn cool. By testing for pressure, I think that he’s measuring the saturated vapor pressure of the gases are various temperatures. That is, for a specific substance at a given temperature, the saturated vapor pressure is the pressure at which the vapor of that substance is in equilibrium with the liquid. Density is mass over volume, so figuring that out wouldn’t be very hard at all. However, I don’t think that density tells us so much, since oderants and lubricants must be considered, not to mention that many things may have similar density. For instance, Ethane (C2H6) is only 2% less dense than propane, which was the same limits of the difference measured between the green gas and propane. But I’m being a little unfair. The various comon chemicals which share similar properties have more tangibly different densities. Butane, for instance, is somewhat more than 2% more dense, while HFC-134 (unless I’m horribly miscalculating) is more than twice as dense. The vapor pressure test is more revealing and helpful in arguing that the tested green gas and propane are one and the same, I think. However, it contradicts some of my practical experimentation. We’ll get to that in a bit.
The icing on the cake though, is the result from tests run on the GC-MS. Carlton has apparently sent in samples of various green gases to be analysed by at Analest Laboratory at the University of Toronto on their gas chromatograph / mass spectrometer. This is now totally out of my field, since the best I can claim is to have been about 3 feet away from one of these at UTD. The Airsoft Innovations site has a good explanation of it, which will be much better than I could do. I also can’t really comment on the validity of the results further than the standard “oh, those graphs look really similar!” Just in case anyone was wondering, I do know that GC-MS is a legitimate scientific instrument which typically produces good results. I can understand that to someone who knows how to read a chromatogram, these results could probably instill a high degree of confidence.
TehLlama adds -- this is quite seconded, the GC and MS check out fully, I've even asked Carl for added data

There has been an unsubstantiated internet claim that “green gas” is actually a fluoropropene rather than straight propane. This claim was found without justification, but I believe that it may have validity. I talked with my local chemistry PhD and verified that it is possible that with the additional fluorine atoms, the final gas would be somewhat less flammable or produce slightly different pressures. However, Carlton’s argument that since the green gas has already certainly been misrepresented there seems to seems to be little incentive to use a more expensive fluoropropene rather than straight vanilla propane is difficult to argue with. For the time being, I would think this claim to be somewhat specious.

Performance

http://www.airsoftretreat.com/gallery/data/561/AIPA_4.JPG

Well, how does it shoot? The answer seems to be: great! It was late at night when my friend James and I got back with the propane. Since, we wanted to prepare for any possibility (i.e. my bursting into flames and running about as a human torch), we locked his dogs (see picture) inside the house and readied the fire extinguisher. Installation took the requisite 15 seconds, and then we were ready to go. I used one of my KSC Glock 19s for this first run, since it was equipped with a metal slide. Results were highly satisfactory. In fact, I felt that the propane was producing greater blowback than my green-and-white camo green gas. I was using the one G19 mag whose fill valve leaked slightly with green gas. With propane, the leak was tangibly greater. I noticed the same with my G26 short mag. This goes to indicate that the propane perhaps produces more pressure. Without a chronograph, I could not measure muzzle velocity, but results from coke can tests were similar to those with green gas. The propane also seems more resilient to the effects of cooldown when compared with green gas. However, the differences in these characteristics can probably be attributed to differences in purity, odorants, and lubricants.

Conclusion

With all the available evidence presented on the Airsoft Innovations site as well as my own experimentation and email discussions with Carlton, I cannot really find fault in his assertion that many green gases are, in fact, simply propane. I believe that he is right.
Given this caveat, the green gas adapter is simply an evolutionary step for the western GBB enthusiast community. The sudden availability this alternative power source is certain to expand the accessibility of gas guns by a significant margin. I would highly recommend it.

Disclaimer #2
Propane is highly flammable. I mean, it’s propane. The Coleman MSDS sheet for propane lists it as the highest of 4 levels of flammability - “Extreme.” So, don’t smoke while you’re filling up. Propane is also a simple asphyxiant. Clearly, don’t have 8 people at a time filling up their entire gas gun collection inside a parked car with the windows rolled up. And of course, it’ll cause frostbite with prolonged skin contact. And don’t get it in your eyes. All this is of course the same as with regular green gas. On the plus side, you can't really accidently injest it. And it doesn't cause cancer (at least not very quickly).

Additional Materials

Links
Airsoft-Innovations.com
AI article documenting green gas / propane testing

Material Safety Data Sheets (MSDS)
In any chemistry lab, you should be able to find a collection of MSDS sheets containing one for just about every chemical that can be expected to be encountered. This sheet typically has important chemical and physical properties, as well as warnings and immediate protocol in the event of an accident (eye/skin contact, injestion, etc). Here are two MSDS sheets from Coleman and Shell on their Propane.

Coleman/Ferrellgas Propane MSDS
Shell Canada Ltd. Propane MSDS

MEDIA SOON TO COME!!!