I am in the hunt for an air compressor for air brushing my models - hope to see all the lastest hobby items at the Hobby Show in Chicago this weekend. I started thinking about my other hobby - air guns. I am also in the market for a carbon fibre tank to fill up my pre-charged air gun. (Scuba shops and in some cases Fire dept. will fill these tanks)
Here is the link to a carbon fibre tank - http://www.airhog.com/tanksets.htm - airhog.com also sells regulators and such. They are not cheap but I do need one for air gunning and I might as well see if it works for airbrushing.
Now a carbon fiber tank will hold a 4,500 psi charge - thats right 4,500 - and has a life span of 15 years. I would think a 88 cu. ft. tank with 4,500 PSI and the correct regular/moisture trap would not only take care of my air gun needs (air guns take 3,000 psi and this tank will fill it about 45 times) but also any air brushing needs.
Any thoughts on whether or not folks are using metal scuba tanks or carbon fibre tanks for this.
If you can get the correct fittings, it sounds as if it will work. The amount of spray time you get will vary depending on the demands placed upon the tank by your habits and the kit requirements. Filling tanks continuously at that pressure, you should ensure you have the tanks hydrostatically tested at least every 3 years.
As as side note, I’ve even heard of people using inner tubes and spare tires as air sources----but not at those pressures…
According to airhogs.com - the carbon fiber tank will work not only for filling the airguns but also as a source for airbrushing. Airhogs was not able to estimate how long a fully charged tank would last. Does anyone here have a calculation for figuring how long a “typical” gravity-fed double-action air brush would last if using a 88 cu. ft. tank filled at 4,500 PSI. An estimate would be great.
Don’t know if it helps but I think that when we use them in the fire service the pressure is reduced to about 70 psi and last 30 - 45 min. I may be wrong but Isuppose if you cut that pressure more than in half you could get over 2 hours use. like I said though, I could be wrong.To add to styrene’s comment about hydrostat testing it As per DOT regulations, 49 CFR 173.34(e), cylinder life on composite cylinders only is restricted to a fixed number of hydrostatic test dates. That number should be five times.
Do you have a tech sheet that tells the flow rate (volume) of air used? It would be measured in CFM (Cubic Feet per Minute). This will have a big impact on use time.
If you can post that I’ll dig around and see if I have a formula.
I’m one of those guys who at one time used a spare tire for an air souce. If I was lucky I got two colors on a small 1/72 scale aircraft done. My arms are still enlarged from pumping up that tire with a bicycle pump. And I can remember having worn out one pump and having to buy a new one. I was young then and that kind of exercise was no big deal. Thank God for air compressors.
claymore68- I will try to find that out. If I can’t find it on the net anywhere I’ll try to find out from the salesman who supplies our air packs. Might be able to contact Scott or ISI who make them and find out also. I’ll see what I can find though.
Don’t know if this applys, but I recently started using a CO2 tank and I love it. At this point, I’m not sure how long it will last, but a 20lb tank charged to 800+ psi I rekon will last awhile. I’ve seen several posts about the possibility of running out in the middle of painting, but the regulator I have (bought from a home-brew beer supply shop) has a guage for tank pressure as well as output pressure so I should be able to fill it (exchange, actually) at my local welding supply before it runs out. And CO2 is clean and dry so a water trap is unneccessary.
But, Yikes! 88 cu. ft. and 4500 psi? If you use it just for airbrushing, it should last forever!
Just for kicks and grins–and to try to answer the question:
I just went to the website posted and the volume of the tank is 550 cubic inches. 550 cubic inches divided by 144 cubic inches/cubic foot = 3.8 cubic feet–a LONG cry from the 88 listed (Most full-size compressed air bottles are less than 6 cu.ft.)
If you multiply the area (3.8 cu. ft.) X working pressure (4,500psi) and divide that by standard pressure (14.7psi at sea level), you get standard cubic feet of 1,163. Divide the standard cubic feet by the cfm of the airbrush (let’s say 10 cfm) and you get the total minutes of operating time at that pressure= about 116 minutes (almost 2 hours). That should give you enough time to spray a couple kits plus adequately clean your airbrush.
Hope this helps,
Gip Winecoff
PS. Airhogs needs to be corrected on their volumes for that particular tank.
Now that we’ve calculated the actual volume and the spray time based on a variable of 10 cfm, it would ceratainly seem that a compressor would be more cost effective than the tank advertised. BTW, if it was an actual 88 cubic feet, the spray time at 10 cfm would be a whopping 2,700 minutes (or thereabout). The only problem would be how to get it home, and where to put it once you got it there. The tank would be HUGE.
Gip Winecoff
I love your ‘formulas’. That’s the first time I’ve ever seen someone show how to calculate that. You know too much, my friend… I am saving this post because I KNOW that I’m going to want to figure that out some time again in the future… (of course, all credit will go to you…)
Thanks for the information on how much spray time to expect from a carbon fiber tank. I had a chance to visit the Iwata booth at the Model/Hobby show in Rosemont and I have to say the compressors are very quite and the double action air brush is a treat to work with.
Looks like I will be going the compressor and air brush route for the model hobby and sticking with the air gun pump for now. I like the power jet model in the case and all I have to decide is on the model of air brush.
It’s a .22 cal, bolt action pre-charged air gun with an 8-round rotary clip. The large tube below the barrel is charged to 3,000 psi or roughly 200 bars. At full setting I am getting 40 shots on a full charge and up to 945 fps. When I get down to 100 bars of pressure the shots are still around 625 fps. A standard compressor can not charge a pre-charged air gun to 3,000 psi
The air gun ammo is nice and cheap about 1¢ a round. For more expensive shooting I take out one of my 8 - M1 Garands from WWII - that fires a 30.06 150 grain FMJ round from an 8 round clip at 2,800 FPS.
Hey, Derek
That 7mm ought to be moving out closer to 2400fpm shouldn’t it? Unless you’re not putting very much powder in the shell… or you’re loading it with black powder…or the barrel’s about 38 inches long
Yes, I’ve been sniffing too much fulminated mercury.
Gip Winecoff
