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To whom it may concern. Regarding: Building a Pneumatic Launcher

Question: How can I use a CO2 cartridge for propellsion, attached to a valve & trigger that is linked directly to the barrel without the use of a air chamber tank? Any ideas of how to engineer this is much apppreciated. Thank you, Gerald J. Wygladalski President & CEO SafeBrella Co.

Question    |  last reply


UV De-chlorination for a fish tank? Answered

I did some research and saw other instructables that showed how to possibly create a UV sterilization. I read that UV light in the 230 and 360 range can break down Chlorine and Chloramines. I was curious if someone could share how to create a UV de-chlorinating chamber (2-5 gallons) with the use of UV LEDs. For safety purposes I was thinking of a plastic 5 gal bin, where placing the top on the bin completes the circuit to expose the water to the UV light in a safe manner. how many would be needed? how long would water need to be exposed?

Question by jc.021286    |  last reply


is it possible to use a chamber capable of firing multiple shots before having to re-fill?

Is it possible to use a chamber capable of firing multiple shots before having to re-fill? cause the way i picture it you could use an attachment to the chamber connecting a independent pressure valve which in turn would be connected to the air tank. the fact that its self regulating would spare you having to fill up the chamber with the turn of a valve after each shot...but even so I'd need a independent pressure valve/regulator (small enough) that would shut the airflow at 100psi. and i prefer the pvc not blow up on me. i'd really like to try it but how and where could i find that type of valve that works similar to scuba equipment??

Question by DIYtheKid    |  last reply


Tennis Ball Cannon

Alright, so ive been into making all sorts of cannons whether they are pneumatic or hairspray, and recently I've been wanting to build a pneumatic tennisball cannon. i came across halve a dozen empty fire extinguishers, i am still deciding if i should use one as the chamber. i am using an electronic sprinkler valve and a 2 1/2" barrel i am also getting a 12 volt (dc) car air compressor (125 psi) and i am going to incorporate this somewhere in the cannon, the air compressor is really small so i could make it built in. i really want to make this cannon portable but i am concerned about the weight of it with the fire extinguisher tank, Any Ideas?

Topic by struckbyanarrow    |  last reply


Can someone help me with my fatal flaw in my spudgun design?

So i have built spudguns in the past and with every new gun i make it gets bigger and better. So i just found pressure rated 3" pvc and im going to use it for a new air chamber. Its a simple end around gun with a piloted sprinkler valve so yea the design is good. Except for one thing. I am enthusiastic enough of a spudgunner to use an air compressor to power it when im at home. but when im at a park or some open feild i bring along a bike pump to pump it up. But with each size up for the air chamber it takes longer and longer and longer to pump. Im not enthusiastic enough to buy a compressed air tank for $60. so what should i do to power it up. i dont have enough room at my house for a distance or height shot and it will take forever to use a bike pump so what should i do. PLESE HELP ME  i will try to post pics of it soon  HELP ME

Question by ostomesto    |  last reply


Designing a better "non-electric" espresso-maker

For people who want a reasonably portable non-electric espresso-making solution that's also affordable, there are a few alternatives. A few examples: Pneumatic: https://www.instructables.com/id/Hand-held-Espresso-maker/ http://www.handpresso.com/ http://mypressi.com/ Brute force: http://unmodifiedpresso.blogspot.se/ Results are--of course--variable with all of these solutions. From what I've gathered, apart from issues with bad coffee, with grind setting/quality or with tamping, the major issues have to do with temperature and pressure. Then there're the issues of convenience/comfort. How would you like to address such issues? Re. temperature, there's the time-honoured method of preheating all the parts by rinsing with just-boiled water. I like the idea in principle but I'd like a way to ensure that the water used for extraction stays in the right temperature range for as long as possible. Possible solutions: 1. Phase change metals such as the ones used in Joulies: http://www.joulies.com/pages/frontpage (different temperature target of course; not DIY-friendly) 2. A large reservoir of hot water. Make the machine hollow so that it can hold a lot more hot water and ensure that this large volume can stay in contact with the extraction chamber. May make the machine more pleasant to hold and use :) a possibility may be to have a water container encircling the existing water chamber in the Presso. Or just pour a lot of near-boiling water in a tank from which only enough water for one or two shots is released into the extraction chamber. Eg. make the Presso's water-reservoir much larger but design it so that only enough for one or two shots is released when the handles are raised to the appropriate position. 3. Insulation. Design as a thermos in such a way that metal parts won't rapidly transfer heat away from the water. What're your ideas?

Topic by Aimless  


Distribution of Solar Heated Water and Any Other Heated or Cooled Water

I started this project about a week ago after seeing the Instructable – https://www.instructables.com/id/How-to-build-a-strikeheliostatstrike-paraboliI made mine out of cardboard and then coated the cardboard – front and back – with fiberglass resin for stiffness. I covered the inside with tinfoil to test it out and find the focal point. It worked great with the focal point at the center of the dish even with the lip of the curve. I then removed the tinfoil and replaced the tinfoil with mirrored Plexiglas. Now it works awesome. I have a 30� parabolic mirror that can ignite wood almost instantaneously at the focal point of the light.Next I constructed the heating coil to run water through. This is made from a large 1 Kg coffee can, 16’ of ¼� copper tubing with end fittings, and the glass lid of a small sauce pan (handle removed). The outside of the coffee can is painted flat black as is the copper pipe. The copper pipe is coiled to a coil 4� in diameter and 6� in length and inserted inside the can with the ends extending from the side of the can through two drilled holes. The inside of the can is not painted, but left shiny. The glass lid is then taped over the hole with aluminum metal tape covering a minimum amount of the glass – about 1/4� around the edge.The coffee can is then suspended over the mouth of the parabolic mirror by a three point 6� chimney pipe stand-off. The can’s mouth is centered at the focal point of the mirror so all of the light being reflected by the mirror must enter the coffee can. Hoses are hooked up to the copper pipe fittings and these lines go to the feed/storage tank.The problem with the conventional set up from here is that the speed the water moves at (slow) to be heated to a great degree causes such great loses through convection, this system is not really feasible. I propose a new idea – or a new twist on an old idea.I noticed that the solar heat generating station use a black water pipe inside a glass vacuum tube to generate heat from the sun for heating water. I said to myself that this is a great idea and plan on building the next heating coil in a vacuum chamber. But, I also came up with the idea that the if the water is heated in this manner, why can’t it be transferred to the storage tank in a similar manner.If the feed lines were suspended inside a larger outer line and the outer line sealed tight and vacuumed the heat transfer due to convection would be almost nil. I estimated that with a total convective area at 100% the use of plastic stand-offs (8 @1/8� thick over 12’) the convective area would be reduced to 0.6%. Unbelievable! Even if this rose to 5% it is far beyond anything in use today by the home owner. Stretches of pipe going 100s of meters would no longer be un-heard of. You could place the dish in a close by field away from the trees and house and pump the heat back without losing it to the ground.This would also work for outdoor wood furnaces if use today. An outer pipe could be added over the existing pipe work, sealed, and vacuumed – almost all heat lose would be gone. And much larger stretches of pipe could be used here also. They would no longer need one furnace for the barn and another for the house. With this system, the pipes could even be run above ground, if desired, in some cases.This could also be used to replace insulation on cooling lines also.The key to the system is minimal contact between the inside and outside lines, and the vacuum between the two lines. Remember, there is no transfer of heat through convention within a vacuum, because there is no air for the heat to transfer through.As with all the new ideas this could get costly depending on the scale of piping you are dealing with – but the savings from reduced heat lose will far out way these cost in the near future.I may get an Instructable out for the Energy efficiency contest, but will be hard pressed.

Topic by strmrnnr    |  last reply


Advice needed on nearly complete instructable

Sorry this is a bit long, but there is an actual question at the end, honest! Every morning at work I walk past a table at the end of our mailboxes that people put give away items on. Its usually a catalog of some form but for a long time now there's been a stack of empty CD spindles and a sign beside them that reads "free to good home." I could have taken them and sorted the mountain of CDs in my office or used them for small parts bins, but to make it areally Good use of empty CD spindles I had to ask myself "IS there an instructable in this?" There are some good ideas for using CDs and a few for the spindles, but at the moment what interests me is hydroponics. So using CD spindles or more exactly the plastic covers they come with I built the basic part of this excellent instructable: http://alturl.com/oa2qt    and I learned a lot of stuff about water pressure and such and once I had built the 2liter bottle method described above I decided to try sealing one of the CD cases and use it for the water container at the bottom of the stack. That took about 4 sticks of hot glue and a couple of burnt knuckles to get a good seal. Turns out there's holes in the center spindle too but I didn't notice them till I had hot glued the container closed. Also ignore the bit of blue air hose inside the container, I was up way too late and flipped the CD spindle 'right side up' which caused me to attach the air hose to the wrong outlet and basically made it useless. I thought I'd need a lot more water in the system than I do so I chose to use a 100ct CD spindle instead of the 50 ct spindles you see on top. (Thanks to all for the ideas on how I could have done it easier!) So far this part of the project was just overlaying the ideas in the excellent instructable above onto the materials at hand. So what I ended up with is an air pump from a fish tank pumping air into the bottom chamber. (the clear hose in center of picture.) This builds up enough pressure to push water thru the blue hose and up to the top CD spindle. I've cut holes the diameter of the air hose into the base of the spindle and this lets water slowly trickle into the Perlite growth medium. When the water reaches the bottom it goes out similar holes in the clear plastic CD cover and starts to pool up a bit to start the process all over again. There is just enough lip on the lid and the bottom of the next spindle to keep it from spilling down the side before this happens. It helps to use the same brand CD spindle all the way up. The clever part of this instructable is that each CD spindle easily stacks in place and you can remove it or change the order without having to dig up or harm the other plants. The base is very stable with several ounces of water in it and I'd imagine you could put 4 of these in a stack and happily swap plants in and out all summer long. The height of the stack depends on how strong your air pump is. I tested two different ones and both were capable of lifting water over 4 feet  up the air hose. Caveat: I haven't actually grown any plants in this yet, so your mileage may vary. Using the stack of CDs for use as apartment planters or sprouting medium would have satisfied the original curiosity for what to do with all those left over CD cases, but in absence of glowing blue LEDs or CO2 lasers I thought Hydroponics would be a great way to sex up the overall idea. I imagine you could use spanish moss or bedding in place of the Perlite, or even soil if you used a coffee filter to cover the holes till you were ready to stick a seedling thru it. This Instructable isn't quite finished as presented. There's a small problem. As you can see in the photo there's a half height (25ct) CD spindle between the water container and the stack of planting modules. Remember that hole I mentioned in the end of the CD spindle? I closed that with a bit of plastic and hot glue, but it made me wonder, COULD I put some sort of check valve here to allow unused water to trickle back into the holding tank YET not lose the hard fought air pressure that's pushing the water to the top of the column in the first place? Since I'm re-using all this old aquarium tech I thought I'd try one of those tiny check valves that keep water from backwashing into the air pump when its off. I'm not sure if it will work in this application or even how much air pressure it will tolerate. This will require some disassembly of the CD hydroponics tower and I thought I'd ask here for suggestions before heating up the glue gun again. So what do you guys think? This has been a lot of fun to think about and I can't wait to bring the media guy  around into my office to see how I've re-purposed the spindles. Just this one last step away…. cheers, flashj  

Topic by flashj  


Idea for a non-ideal Carnot cycle based engine.

Initial Stirling engine conceptFor some time I was contemplating an idea for a Stirling engine that would work quite differently than the other designs that I came across. Whole internal volume of an engine may be viewed as a closed-loop pipe, trombone-like slide mechanism allows this pipe to change its length. Electrical fan replaces displacer and pumps working fluid throughout the engine constantly and in one direction. Some portion of the pipe is replaced with branching structure that consist of two heat exchangers (hot and cold) and regenerator. On both ends of this structure special valves are located that connect one of the structure’s parts to the main pipe, so that whole engine forms one closed-loop. While this happens, both of the unused parts are completely bypassed.This design should have many advantages. Working gas is in constant motion and little energy is wasted on accelerating it. Gas may pass many times through heat exchangers, allowing for much better approximation of isothermal processes. Disconnecting unused heat exchangers from the rest of the engine should minimize volume of dead spaces.There are some drawbacks to. Slide mechanism allows only very small changes of total volume (compression ratio is low), and that limits engine’s ability to operate with higher temperature differences. Piston, which is part of the slide mechanism, and especially valves, are heavy and this makes them unsuited for high speed operation, making the whole engine bulky. I also except that an area of all surfaces that are sliding against each other and produce friction would be higher than in traditional Stirlings.Problems with Stirling cycleIdeal Stirling cycle (Fig. 4) consist of two isothermal processes (constant temperature) during which work is performed, and two isochoric processes (constant volume, no work performed). Isochoric processes function is only to change temperature of the working gas, and this takes a lot of energy to do so (especially if gas with high heat capacity is used). Regular Stirling engines try to minimize this inefficiency with regenerator. But when I tried to analyze this process mathematically, I noticed that even regenerator with very high heat capacity cannot store more than half the energy needed to perform next isochoric process (see lower left part of the spreadsheets for more details).Fig. 5 represents heat pump (or refrigerator) working in a modified Stirling cycle. Isochoric processes represent transfers of heat to and from the regenerator. Rest of the temperature change is performed by polytropic processes, during which heat flows to or from the heat exchangers and also work is performed. I chose to represent heat pump, instead of a engine because engine working with this modified cycle wold require isochoric processes to be performed midstroke (or transfers of heat to regenerator would have to be performed during polytropic processes, when working gas changes its temperature also due to work being performed).Note that I am using word polytropic to indicate processes where gas changes its energy both due to heat transfers and work performed. When special cases of polytropic process are mentioned (isothermal, adiabatic, isochoric) I use their specific names.Solving those problems with Carnot cycleLegendary Carnot cycle consist of two isothermal processes (just like Stirling cycle), but changes of temperature are accomplished by the adiabatic processes (no heat transfers with the surroundings), instead of isochoric ones. This has huge advantage, because when energy is added to the working gas during adiabatic compression, all of it can be later recovered during adiabatic expansion.Design I previously mentioned can easily be adapted to work as a Carnot engine. Only change that is necessary, is replacement of regenerator with the empty pipe (ADIABATIC PIPE in Fig. 2). When valves connect this empty pipe to the rest of the engine, there is no heat transfer between working fluid and thermal reservoirs. Any changes of engine volume modify temperature and pressure in a approximately adiabatic fashion. To model what happens with the engine I used slightly modified Carnot cycle (Fig.3). Just before adiabatic process end, short polytropic process begins. It is done so that loses associated with valves connecting both adiabatic pipe and heat exchanger to the main part of the engine for a short period of time can be better simulated. Heat pump working in this cycle is shown in Fig. 6.Design detailsEngine uses special valves, which external shape resemble truncated cone. Smaller base of this cone faces main part of the engine, larger one heat exchangers. Inside there is a pipe, with one opening right in the center of smaller base. The other opening is located off-center on the larger base, so it can connect to the one of the heat exchangers or adiabatic pipe (which are situated just like chambers of a revolver’s cylinder in respect to each other). As this engine engine will most likely operate under low RPMs, flywheel will have to be connected through a transmission with very high gear ratio. The flywheel will have to be quite bulky as well. This poses another challenge, as the pressure inside engine’s tubing will be higher than atmospheric, and at least space around the other side of the “piston” will have to be pressurized as well. If only the immediate surroundings will be pressurized, and gears, flywheel, electric motor/generator will be outside of the container, then very inefficient seal will have to be employed. If everything will be located inside the pressurized container, then fast moving parts will be working against dense gas. Pressure in this area ideally should have such a value, so that on every piston stroke energy is both added to the flywheel and extracted from it as to make energy storage requirements more manageable. This requirements may also be further reduced by employing some other energy storage form. And of course exchange of heat between main part of the engine and this pressurized section must be taken into consideration.Then, there is problem of heat exchangers. They can be either large diameter pipes with fins, or smaller diameter ones that are densely packed (this seems to be must popular configuration in Stirling engines). As heat transfer with the outside of the engine takes around half of the piston stroke, it might be a good idea to employ two pumps of heat transfer fluid per each of the two heat exhangers. One would work constantly to transfer heat from some large heat reservoir, the other would transfer heat to the working fluid only when it is necessary. Some another heat exchanger would have to be placed between those two circuits.And there is also a question of the piston. Basic trombone-like version could be replaced by the something similar to the design drawn in Fig. 7, where two parallel tubes, connected by U-shaped piston, are replaced by the coaxial pipes with volute on the outer section that allows connection another parallel pipe. Piston itself has then small tubular part attached which allows working fluid to pass from outer section to the inner section. This design has only one high pressure seal, is possibly lighter, but fan that pumps working fluid will probably need to be more powerful. Problem of sideways motion of the piston must also be analyzed, and it can be either resolved with piston skirts or the crosshead. Interesting aspect of this problem is that while most frictional forces in the engine are mostly independent of the engine speed, forces associated with this sideways motion of the piston increase with engine rotational speed.Another possible improvement would be making adiabatic pipe shorter than the heat exchangers, which would reduce volume of dead spaces.Engine parametersIn case of a engine that uses helium as a working fluid, has minimum volume of 46.7 liters, maximum volume of 70 liters, operates at temperatures of -5°C and 37°C with the speed of 15 RPM you can expect that it will produce 1138W of power at 8.13% efficiency.In the case of heat pump that operates at the same parameters you can expect that it will require 2300W of power and achieve COP 4.95You can find calculations, diagrams and the detailed descriptions inside non-ideal_carnot_engine.zip (it is unfortunate that Instructables do not support uploading .zip files and other file formats any more, and I have to use another website just to upload few spreadsheets).Possible applicationsI started thinking about this concept when considering applications of thermal energy storage. In more northern latitudes largest factor in domestic energy consumption is heating. So, at least in my opinion, any movement toward replacing fossil fuels with renewables should focus on this largest contributing factor. And this actually is quite fine because storing 1 kWh in a tank filled with water, rocks/concrete or simply in the ground is much cheaper than storing it inside lithium-ion batteries. And general idea behind this low temperature engine, was that some part of this large amount of energy stored to be later used to heat buildings, could be converted into electricity.It should also be able to work in reverse as a heat pump or refrigerator.

Topic by rarinn