Introduction: Hydroxy Gas Generator
YES, you can melt rock, fuse glass and even boost an I.C.E. ... no Cyril not the ice in a fridge, an Internal Combustion Engine.
But first you'll have to toss out the schoolboy experiments with carbon rods and paper clips dipped in saline or baking soda solutions.
That was fine to demonstrate a concept with lighting the soapy bubbles, but thats pretty much all you're going to do.
If you want to move into the future, then....
Its time to build a better electrolyser.
Better than what you ask?.... well better than all the glass pickle jar and tupperware container contraptions out there.
Step 1: Safety First and Procedures
I cant stress strongly enough that pickle jars or glass jars of any type are not suitable containers to generate hydroxy gas. The slightest accident is going to turn that glass jar into a glass grenade with the unpleasant side effects that usually accompany such events.
To prevent flashbacks you will need a water trap otherwise known as a bubbler, which also has the added benefit of scrubbing the gas clean of caustic vapours. Dont rely on existing arrestors as used on oxy/acet gas welders, the flame front speed of hydroxy is way too fast for them to contain the flame.
The electrolyte I will be using is NaOh a.k.a. Caustic Soda a.k.a. Sodium Hydroxide. Not baking soda, it creates carbon monoxide and erodes the stainless steel electrodes.
I get mine as caustic soda flake from the hardware store, but it is also possible to get decent quality from other places in drain cleaner form. Make sure if going the drain cleaner route that it doesnt have additives or aluminium shavings added.
Caustic soda is as its name implies very caustic, and rubber gloves will be the order of the day if you dont want to see your skin start peeling away. Its probably also wise to add eye protection too.
Initially I start a cleansing cycle with very dilute 5% caustic soda in distilled water, and then the conditioning phase with full strength 23% NaOh in distilled water which is then the time to keep your wits about you.
Note, I dont use river water or tap water or melted Italian snow water or something sucked out of a rock layer far below the surface. I dont want spiders, bugs and chemicals in my 'lyzer, so its less hassle if I start with the good and clean and fresh stuff...trraaalala.
Dont use baking soda, it creates carbon monoxide and erodes the stainless steel electrodes.
Dont use salt, it gives off chlorine gas, very nasty stuff.
- I use the term Hydroxy in the loosest sense in that I infer it to mean a stoichiometric (2:1) mix of Hydrogen and Oxygen in a common duct electrolyzer, and not a gas consisting of mono-atomic Hydrogen.
Step 2: Design Stage
Electrolytic gas generators have been around since 1916 (US Pat. 1219966) as a quick search on google revealed, possibly even earlier.
That said the 2 main types are the parallel and series versions. Of the 2 the series version is the more efficient type while the parallel versions are usually easier to construct and maintain.
In the parallel type cells you can have parallel connected electrode plates or series connected plates.
More on the different types later.
My preferred choice of gas 'lyzer remains the series type cell because of efficiency.
However the construction is usually more tricky with the series flat plate versions and so I
decide to "roll my own" easier version.
This design was seeded by Nick Stone's "Newb Tube" on the Aquauto.com site. I decided to build my own Newb Tube instead of pointing out all the mods and tricks he should try....thanks Nick :)
My criteria were,
1.cheap S.S. electrodes (tubes),
This meant I needed 7 cells because rule of thumb says 2V drop across each cell, any more is wasted as heat buildup. However it would'nt be practical to have 8 tubes as it would start taking up space and be awkward to handle/install. A set of 8 nested tubes would also be prohibitively expensive.
Eventually after mulling it over I settled on 3 X 3 nested tube setups, series connected to give me the 2V voltage drop across each cell.
However, due to differing square area's of the different size tubes, it actually had a 1V drop across the Neg outer and the neutral inner with 3V across the pos washer stack and neutral tube. This was with 12V across the whole cell and 4V across each tube set.
Guess a Triple Newb Tube is a good a name as any.
I've also added two different CAD formats(DXF and DWG) of the design, all measurements are in cm.
Step 3: Series Cells
In the series type you have isolated cell electrolytes, with the electrolyte of each cell isolated from the next one, ie no water level equalisation holes drilled in the plates.
You can also have a series connected, common electrolyte (open bath) cell which isnt as efficient as the true series cell, being a lot closer to the parallel cells in operation efficiencies.
Examples below, the cell on its end is my big daddy 120 plate series job(119 cells) for running directly off rectified domestic 240 V AC. The negative connection is at the bottom already in the case with the pos awaiting its turn on the left. There are no equalisation holes drilled in the plates, so its a true series cell as long as the electrolyte level stays below the plate tops.
Step 4: Parallel Cells
This is a parallel connected open bath design by Shigeta Hasebe us pat 4747925.
Ignoring the magnet you will see that every alternate plate is either connected to a pos or the neg power bar. The plates are usually fully submerged in a parallel design.
A good example of 2 parallel groups of series connected plates in an open bath type cell is the Smacks Booster. Smacks home page
Step 5: Electrode Materials
The material of choice is Stainless steel 316L, failing that you could use 304L or even plain old 304 SS.
The plain 304 is cheaper, but will take longer with the conditioning phase due to the higher carbon content, more about conditioning later.
Seeing as Im using M6 threaded rod and M6 nuts and washers which are only available in 304 grade, I went with 304 tubing too.
The inner tubes are 125mm long, the threaded rod is 180mm long and the outer tubes are 200mm long giving me a 60mm working space for foam, sloshing and whatnot.
Step 6: Electrode Preparation
The steel will need to be prepped before decent efficiencies and gas rates are obtainable.
Typically the plates are cross hatch sanded, front and back of the entire plate.
It will be obvious to those skilled in the art that to cross hatch the outside of tubes could be tricky, as well as sandblasting the inside of the tubes. Therefore I blasted the outside and attacked the insides with the brake cylinder hone.
Then the plates are washed clean. The plates should NOT be touched with grubby paws after washing due to fingerprint oils contaminating the plates and reducing bubble formation in that area.
Once the grubby paws are covered in rubber gloves, then assemble and begin the cleansing stage ( 3 days - a week).
Then the conditioning stage also about 3 days to a week. In between the electrolyte will sludge and have to be flushed and replaced with some good and clean and fresh stuff......
For the very last word and finer details on plate prep, the excellent article by Bob Boyce who is legendary in Hydroxy circles is attached.
Step 7: Internal Parts
The Anode, (positive electrode) comprises a stack of SS washers and nuts. Next is the "neutral" electrically unconnected inner tube which is fastened down to the base with the inner spacer.
Last pic is a shot down the tubes to see how it fits together.
Step 8: Internal Spacer
Because this is my own design, the internal spacer needed to be custom built too.
Alas I dont have a lathe or plastic injection equipment, so I had to do it the hard way with a modified tank cutter.
1. cut out the disk from a square to match the inner diameter of the outer tube very closely.
this is to prevent the center anode (washer/nut stack) and the inner tube from moving around and shorting out and also to maintain a uniform distance between tubes and washers.
2. cut the inner gas holes, I used a 3mm bit but larger can also work.
3. cut the slots for the outer tube gas holes, I used a rotary file 6mm dia.
You can then assemble the spacers onto the anode stack which tightens down the stack onto the base plate.
Step 9: Overview
A sort of cut-away to illustrate how it all fits together.
The whole shebang is held together with 8 SS threaded rods.
Dont forget to clamp every hydroxy hose, helps prevent leaks.
Step 10: Perspex Caps
Here we do the perspex top and bottom caps. I went with perspex (Plexiglas®) because it can handle decent temps and resists NaOh.
These are 15mm thick pieces with 2 seat grooves "tank cut" on the bottom plate and 1 seat cut for the outer tube on the top plate.
Nitrile rubber O-rings, also known as Buna-N are then placed into the seats and the tubes then seat against the o-ring sealing the gap as well as insulating the perspex from direct heat.
The nitrile has good resistance to acids and bases. It also offers excellent resistance to petroleum-based oils and fuels, water and alcohols. The temp range is -55ºC to 120ºC.
The front perspex piece has been flame-polished with my favourite gas, hydroxy, the rear one which is the bottom cap has been left alone for comparision.
The top cap in the foreground still needs to have a water fill port drilled inside each tube seat, the threaded hole is a standard ¼in BSP compressor fitting.
The bottom cap has been drilled and tapped for stainless steel M6 threaded rod.
Don't forget to use teflon plumbers tape on all threaded connections, it helps greatly with leak prevention.
Step 11: Power Connections
Lugs were used to make power connections to the 'lyzer, and also 3 stainless steel hose clamps to make a connection to the outer tubes, I dont have a MIG welder and I also didnt want to heat the heck out of the tubes.
I used M6 type power connections seeing as I shouldnt be exceeding the design current of approx 8.5Amps.
Rule of thumb says not to exceed 0.5 amps per in², or face electrode erosion at an accelerated rate. That would equate to 0.0775A per cm², so taking the smallest tube area, the inside of the inner tube which is 111.57cm² X 0.0775A= 8.646A max.
I have seen figures of 0.1A / cm² for 304SS and 0.15A / cm² for 316SS on youtube, but felt more comfortable with figures from long-time experienced experimenters with this technology.
Step 12: The Bubbler
The bubbler can be made in any number of ways, for large gas flow rates I use an old water filter housing that I've modified.
The nylon sight tube is a necessary feature and I made mine in the top cap to indicate the highest water level. Safety dictates that the smaller the volume above the water, the smaller the explosion when you get a flashback.
This device has taken care of a few flashbacks without any problems
Other embodiments of bubblers include but are not limited to 20mm clear vinyl tube as in the pic below, and also Sch 40 PVC pipe with end caps can do serviceable duty as a bubbler.
Step 13: Show and Tell
Anyway heres a pic and the video of a hydroxy flame burning underwater.
The water has to be heated somewhat as cold water merely extinguishes the flame. Pictures of melted glass panes and glazed pebbles probably wont be that interesting, its one of those have to be there things :)
I've also included an excel spreadsheet to calculate millilitres per minute per watt which is a nice way of comparing different cells outputs.
Flat plate series cells are mostly 7MMW and up, I've never built a parallel cell so I cant say too much about them.
Some facts from me:
This tube version is 5.75MMW at the moment with probably another week of conditioning left, I expect it to easily get to 6.5MMW.
Flow rate is 600ml per minute which I expect to double seeing as it has double the square area of my flat plate series 7 cell which puts out 600ml at full chat.
Temp after 4hrs is 66ºC on the outer tube and 73ºC inside electrolyte.
Lastly a mod which appeared to drop the power requirements by ± 1A , is to apply shrink wrap to the inner spacer locknuts.
It appears that the open nuts contribute to current leakage which means additional unwanted heat
Pic attached for clarity.