Friday, May 9, 2008

Compressed Air as an Alternate Energy Source?

By A.R. Tinkerer

New Name
To start with, I have some minor bad news. I discovered that AirNergy is a registered trademark of Global Energy; WindPower, Inc.
Because of this, I will no longer be using AirNergy as the name for this blog. As of this post, the name will be PneumoNergy (pronounced nu-mon-r-je).

850 AirMagnum Conversion
For those who are waiting for another installment about the PCP conversion for the 850 AirMagnum, I made a face spanner wrench to open those stubborn valves. Find out more about what happened in the next post.

Gas Prices
The way gas prices are going, alternate sources of energy are looking better and better. What upsets me is that gas companies are making record profits while they continue to raise prices. This has gone on at least since 2005, if not earlier (see the MarketWatch graph)! Note that they claimed 2007 would be a more difficult year to follow up with record profits.

2005 profits
ABC News

2006 profits

2007 profits
International Herald Tribune
Daily Mail
San Francisco Chronicle

The New York Times

Practical Uses
There are companies currently working on using compressed air as an energy storage mechanism for small cars and trucks, see
Introducing AirNergy. Compressed air could also be used an energy storage system for other uses. Air engine generators could run off the compressed air to generate electricity, and pneumatic tools could run directly. Hydro, wind and solar sources (have you heard about the new solar panels that are 1/10 the cost of the old ones?) can be used to compress the air, and compressed air has an advantage over batteries because of the lack of chemicals!

Hobby Uses
Compressed air engines could be used to power R/C vehicles (with small batteries running the electronics).
Mike Smith's Compressed Air Engines web site shows his work with small compressed air engines. I intended to provide the link in the Introducing AirNergy post, but I couldn't find it. I have now added Mike Smith's link to the "Hands On" section of that post as well.

Problems and Solutions
Of course there are some problems associated with using compressed air for energy storage.
1) High pressure tanks need testing. This might be solved with new tank materials and manufacturing processes, but for now, testing has to be done. Battery banks also need to be replaced periodically. It might also be possible that larger, low pressure tanks would be a more practical solution.
2) The overall efficiency of the system may be low. I don't think this is a big problem if you are using natural sources to compress the air in the first place. Efficiency will also increase as the technology develops. The article, Advantages of compressed air as an energy vector, discusses the efficiency of using compressed air.
3) Tank space might limit the practicality of using compressed air.

Your Turn
If any of you have opinions, ideas, or other problems and solutions, etc., let me know what you think.

Thursday, February 21, 2008

RWS 850 AirMagnum PCP Conversion - Part 3

By A.R. Tinkerer

Part 1
Part 2

I can't believe it has been a month since my last post! Sorry about that, I hadn't planned on taking so long!

When I see a DIY project, I often wish that I could find out more about what went on in the design and build process. What options were rejected? Why? Why was a certain material used? Where are the parts available? How were the problems solved, etc.? So today, I will look at the design criteria I originally used for the RWS 850 AirMagnum conversion and explain the reasons for each. After that I will discuss some modifications made to the valve and the results. If you have any questions or suggestions, please let me know.

I started out with five design criteria. Each one is listed below with the reasons for it.

1 - Use off-the-shelf parts
The main reason to use off-the-shelf parts is to keep things simple. The only equipment I had for working with metal were a drill press, Dremel tool, hand tools and welding equipment. That limited what I could do.

Another reason is safety. If you make your own parts, you have to figure out what materials to use, how to calculate part strength, how working the material will change its properties, etc. This was more involved than I wanted to get since the pressures involved are high.

I used paintball parts for everything in the air path. Paintball parts are made for the high pressures. I did modify some of the off-the-shelf parts in the setup shown last time.

2, 3 - Air supply on/off; Removable air tank
These two items are related. I wanted to remove the air tank and the air must be turned off to remove the tank. There are two reasons for removing the tank. The first reason was to make it safer around kids.

The second reason is related to travel. I went to a friend's house for the weekend and drove to work on Monday. After arriving at work, I realized there was an almost full CO2 tank connected to the RWS 850 in the trunk! I had three options. Leave it in the trunk, get permission to bring it inside or empty the tank. Leaving it in the trunk was not an option since it was a warm day. It was in a locked gun case, but getting permission to bring it inside could be a problem. Fortunately, permission was granted. With a removable air tank, I could have brought the tank inside and left the airgun in the trunk - no problems.

4 - Speed of at least 650 fps
The reason for this is explained in Part 1. Basically I needed more power for my specific use.

5 - Price under $150
This one is pretty obvious. The original cost of the RWS 850 was $240 and adding $150 for a conversion would put the total cost at $390. The cheapest multi-shot, PCP rifle at Pyramyd Air was around $390 at that time. I didn't want to pay that much when I could have bought a PCP in the first place!

Valve Modifications
After the disappointing speed of 619 fps @ 1050 PSI last time, I figured it was time to open up the valve. I found an adjustable face spanner wrench (or pin spanner wrench) at TrueValue hardware, ground the pin diameter down so they fit and opened the valve. I used a pin punch to tap out the puncture pin and a filter screen fell out with it. After the puncture pin was out, it was easy to see that it was pressure fit into the valve. Originally I was only going to remove the puncture pin. However, I decided to do a little more. I used a hand reamer to ream away the puncture pin seat and to taper the exit hole slightly. I then polished both the entrance and exit holes. Here is a link with pictures of an unmodified, disassembled valve.

The disassembled and modified RWS 850 valve

When I put the valve back together, I used threadlocker to lock the threads and seal it. I tried both blue threadlocker gel and regular blue threadlocker from Permatex, but neither worked. It would leak air when pressure was applied. Thinking back to when I took the valve apart, I remembered I had seen something that looked like dried white glue on the threads. White glue is similar to wood glue, but wood glue is supposed to be more flexible when dry, so I tried wood glue. That worked. In fact, I've tried to open the valve again and haven't been able to.

Trying the modified valve
The valve was back together, it wasn't leaking, so time to try it out! I put together the same setup as last time, loaded the gun and fired. Psssssssss.... where was that sound coming from? I turned off the air and checked. It was coming from inside the valve! I unloaded the gun, shot the pressure down, removed the valve and took a look at it. There was a small piece of spiral shaped aluminum stuck in the valve! Apparently the extra air flow had caused the Cooper-T adapter to let go of some aluminum debris left from the machining process!

Once the debris was cleared, I set up to record velocities starting at 1000 PSI down to 850 PSI at 50 PSI increments. I shot two shots at 1000 PSI and turned off the air so I could adjust down. Psssssssss... what now!!! The on/off on the regulator had failed!!! I frantically played with everything to try to stop it! Finally it stopped after losing 1000 PSI of pressure. At this point I had the output pressure set to 850 PSI and wasn't going to get a nice table at 50 PSI increments! Oh well, I might as well record the speed at 850 PSI!

Here is the "table" using .22 caliber JSB Exact Jumbo pellets.
1000 PSI: 685 fps
850 PSI: 660 fps

That works out to 15.29 foot pounds @ 660 fps and 16.47 foot pounds @ 685 fps. The advertised weight of 15.8 grains was assumed for the pellets. The same setup with an unmodified valve recorded a speed of 619 fps @ 1050 PSI, so that is a nice step up in speed! If you are interested in speed/energy calculations, there is an article and calculator at the Pyramyd Air web site.

Things Learned
-Plan ahead when travelling with guns.
-Machined parts may have debris in them.
-Using a lot of wood glue worked to lock and seal the valve closed. It worked too good for taking it apart again! I filled the threads with glue, screwed it together, wiped off the excess, unscrewed it, wiped off the excess and screwed it back together.
-There are potential problems with an on/off air source.
-There is restricted air flow in the standard RWS 850 valve. There are a couple of possibilities for where this exists. One possibility is that the valve volume may not be large enough. When I enlarged the entrance to the valve, the extra pressure and air flow could have compensated for this. Another possibility is that the valve and/or hammer springs need to be changed to allow all the air in the valve to be used. It could also be a combination of the two.

There are more parts to come about this conversion, but next time I will probably discuss the possible applications for air power and some problems with it.

Monday, January 21, 2008

RWS 850 AirMagnum PCP Conversion - Part 2

By A.R. Tinkerer

Part 1

Last time we looked at the performance of a .22 caliber RWS 850 AirMagnum using air (actually nitrogen) instead of CO2. It was connect to the nitrogen source using a paintball remote setup. Today we will look at a different setup. This time the tank was filled with air, but that shouldn't make much difference.

I was puzzled by the results from my first test so I began to figure out why the results weren't better. The first thing I did was to set up a pressure gauge on the paintball tank to check its output pressure. It read 800 PSI. Pressure for CO2 at room temperature is about 850 PSI, so that could explain at least part of it.

Next Step
At this point I decided that if the project was worth continuing, I might as well convert my 850 AirMagnum into a true PCP (Pre-Charged Pneumatic). I began to look for small tanks that would fit under the barrel and a paintball regulator that would put out higher pressure. I found a 13 ci (cubic inch) tank, a Smart Parts Max Flow Inline regulator, and put together the setup below. Finding the parts to connect everything was a challenge since I used only off the shelf parts. I did have to drill and tap one part.

RWS 850 AirMagnum PCP

The tank and regulator are connected to the adapter via paintball macro line. The Smart Parts Max Flow Inline regulator is great because it is adjustable and has an on/off built-in. Not only that, but it has a tank pressure gauge and an output pressure gauge!

Tank, regulator & adapter closeup

The adapter includes the Cooper-T AirSource to ASA adapter discussed last time plus a customized adapter with a burst disk, macro line connector and bleed plug. The customized part is a Palmer's Pursuit adapter that has been drilled and tapped for the burst disk and macro line fitting.


The mount is made out of a Daisy scope mount. Rubber gasket material protects the barrel and a Lucky Paintball drop forward mounts to the regulator.


Testing the new setup
I planned to test the new setup by setting the regulator to around 800 PSI, shooting a couple of shots, then increasing the pressure by 50 PSI. I would continue until I reached 1000 PSI. That would give me a nice set of results for 800, 850, 900, 950 and 1000 PSI. With that spread I should be able to see what pressure the AirMagnum liked best. Things didn't go as planned. I set everything up, turned on the regulator, and the output pressure was lower than I wanted. I tried to adjust it and found that it wasn't easy to adjust the pressure with the air on! Ok, I figured I'll go to the maximum pressure and try to adjust down. Maybe that would be easier. I turned off the air, adjusted to maximum and was pleased to find the regulator put out about 1050 PSI. I shot a couple of shots and tried to adjust the pressure down. It was just as hard to adjust down as to adjust up! So I shot the rest of the tank at 1050 PSI and did some testing with the RWS compensator I had just purchased.

This time I was shooting with a friend who owned a commercial chronograph. Unfortunately the light wasn't right or something else was wrong and we were only able to record the speed of one shot. That shot was 619 fps. At first I thought even that reading must be wrong, but after posting my comment on the Pyramyd Air blog, BB Pelletier commented that I might be experiencing valve lock at that pressure (1050 PSI).

Going futher
I didn't like the look of this new version and it was difficult to adjust, so instead of trying to test further, I decide to go back to the drawing board once more. At this point I am going to go backwards and explain the original design criteria. Then I will fast forward to the next design and the search for components to fit those criteria. Don't worry, I will post some intermediate results next time.

Friday, January 18, 2008

RWS 850 AirMagnum PCP Conversion - Part 1

by A.R. Tinkerer

My start in airguns came in about 2005 with the purchase of a Crosman 781AK kit. I was unfamiliar with airguns and three of its features clinched the sale. The 781 is a single pump, multi-shot, BB and pellet gun. I don't remember why the dual ammo attracted me, but it did. I intended to use it for pest control and since I didn't shoot much, I wanted to be able to take a quick follow-up shot. I figured the multi-shot and single pump features fit this bill. This was also a spur of the moment purchase.

Fortunately, about that time, I came across the Pyramyd Air blog. After doing some reading, I began to realize the 781 was not powerful enough for pest control. So began my search for the perfect airgun. The RWS 850 AirMagnum had recently been introduced and seemed to be a good choice. If the Benjamin Discovery had been available at the time, I would have bought it (even though it wasn't a repeater)! This post also wouldn't be here (and probably not this blog). Anyway, I ordered the .22 caliber AirMagnum and couldn't wait to use it after sighting it in. Soon I had a chance.

To make a long story shot, I shot a pest that we had problems with. However, it wasn't a quick kill, so I decided I needed more power. I had read that using air in a CO2 airgun would increase the power, so I began to research a conversion for my gun. Later I discovered that one problem was that I should have taken a head shot.

The First Conversion
I did quite a bit of research on the web to figure out how to convert to air. What I found is that paintball is a great resource! My requirements for the conversion were to keep it simple and use off the shelf parts, and most of these were available from paintball stores. But I had one problem. I couldn't find an adapter to convert the AirMagnum's Crosman AirSource connection to a paintball ASA.

Some Paintball Terms
ASA - Air Source Adapter, the adapter a paintball tank screws into
HPA - High Pressure Air; high pressure air is sometimes used instead of CO2 (carbon dioxide)
Marker - official term for a paintball "gun"
Remote - setup that connects the paintball tank to a paintball marker

One problem I had with finding an adapter was that I didn't know exactly what I was looking for. I started thinking about how I could cut off the threaded part of the AirSource bottle, drill it, thread it and other creative ideas. It all seemed like a lot of work to me!

Crosman AirSource cut open

Finally I ran across an AirSource to Paintball adapter from Cooper-T. That was the ticket! It was a Crosman AirSource to ASA adapter with a check valve. After buying the adapter, I also bought a relatively inexpensive HPA tank and remote. I had everything I needed!

Remote quick disconnect; Cooper-T adapter (red)

Remote with Cooper-T adapter

A note about Cooper-T
Unfortunately the man who ran Cooper-T passed away. The Cooper-T web site is still up, apparently to clear out inventory. There are some complaints on the web about long waits getting Cooper-T parts now, but that may be understandable given the circumstances. Other sources for AirSource to ASA adapters have become available recently. My condolences to Cooper-T's family.

Now that I had my conversion, I was anxious to try it. I found instructions for a DIY chronograph and set up my own. For my setup, my first paper was 5 feet from the gun and the second paper was 10 feet from the first paper (15 feet from the gun). I set the microphone recording volume to 50% (but NO microphone +20dB boost) and started recording.

The conversion of the .22 caliber 850 AirMagnum performed as follows with Nitrogen. I used Nitrogen for this test because the paintball store I filled at only filled with Nitrogen. JSB Exact Jumbos were used for the test and velocities ranged from 591fps up to 602fps with an average of 594fps (12.38 average foot pounds). That makes this setup about the same as CO2 on an 80 - 90 degree day. (The CO2 results for comparison came from comments on the Pyramyd Air blog.) It was 73 degrees Fahrenheit the day I tested.

Disappointing Results?
Was I disappointed with the results? Yes. I was hoping for better than CO2 performance, not just the same as CO2 at higher temperatures. The tank and remote setup is also kind of clumsy.

Things Learned
-Know what power level you need for hunting different size pests.
-Know where to aim to be humane when hunting. This may be different than where you would aim with a firearm.
-Quite a bit about paintball, high pressure air and air fittings.

What Now?
I have gone through a couple more versions of the conversion that I will describe in future posts. When I am done with my latest version, I will also post that. Following are a few projects/discussions I am planning for the future.
-Discussion on air power feasibility: problems and some solutions
-Discussion on possible uses of air power
-More installments on the RWS 850 AirMagnum conversion
-Air powered R/C plane
-DIY chronograph (using phototransistors)

Wednesday, January 16, 2008

Introducing AirNergy

by A.R. Tinkerer

Welcome to the AirNergy blog (note that the blog name has changed to PneumoNergy since AirNergy is a registered trademark of Global Energy; WindPower, Inc.)! This blog is to document building or modifying devices that use air as their energy source. For each project, I will try to include the original idea, the design, construction, tools used, problems encountered and things learned. Projects may get sidetracked to describe making or modifying something needed to complete a project.

This blog will not be updated daily. I don't know how often I will post, and it will vary.

I like to tinker. Look up "tinkerer" at and that describes me. I like to fiddle with, adjust, repair and make things in an experimental manner (and hopefully not entirely in an unskilled way).

I was fortunate enough to be able to take metal shop in high school. The main things I remember from the class are arc welding and the metal lathe. However, that was a long time ago and I discover how little I remember each time I do something! I usually have a vague idea from those memories of how to be safe and where to start, but I make mistakes. I hope I learn from them and by exposing my mistakes here, you can avoid them. I hope you learn something and I look forward to learning from you.

Where Credit is Due
I must stop here and credit two sources which peaked my interest in what compressed air could do. Those sources would be the MDI air car and airguns. But that isn't the end of the story. Tom Gaylord, AKA B.B. Pelletier (Pyramyd Air blog), was the one source that is probably most responsible for feeding my interest. Thank you Tom!

I also must give HUGE credit to all of you who post information about your projects! These have been a great resource for me. I will try to post links to any web references I use in my projects, and list books, magazines, etc. that I use for reference.

Finally, I must thank God who gave all of us the ability to think, reason and create.

Lets get started
To kick things off, here are a few links I found interesting that relate to using compressed air for an energy source. There is one other link I wanted to include under the "Hands On" section, but I couldn't find it. I will post it when I do.

Compressed Air Engines

Hands On

Air Car

Jay Leno's Green Garage (note the link to the wind turbine)

The next post will introduce a project to convert an RWS 850 AirMagnum CO2 (Carbon Dioxide) airgun to use HPA (High Pressure Air). I will explain why I started the project and its humble beginnings.

And finally I must make a disclaimer.

DISCLAIMER: This is not a how-to blog, it is informational only. Working with power machinery is dangerous and some of the things I build can be dangerous. WHATEVER YOU DO IS AT YOUR OWN RISK.