barzn Posted March 15, 2015 Posted March 15, 2015 "I've been told a mesh provides approximately the same area as a plate would." - I actually thought that it will most likely be that way.. and for a small anode (not industrial scale) this assumption seems o.k to relay on for me. so thank both you and WSM for confirming this! "The anode will determine the max you can put in to the cell. It will simply fall apart from overheating if you push to hard. Different types of anodes, different mA's as max. I've been hearing 300mA as a rule of thumb, a lot, but where the number comes from.... No idea.At the same time the cell will overheat if you have a small volume in relation to what your anode can deal with. Your better of with "to large" a volume, and insulating the cell slightly to get the working temperature you need / want. Which also is dependent on the anode, with LD i hear the limit is lower then you'd really want the cell at, 50-55c as an absolute max." - really helpful information, sure i'll keep that in mind as i would use the TSLD soon enough "You and me both. I think i want a stainless steel cell, with a rod in the center, and a round, mesh LD anode around the rod. Using the cell as cathode, and using wishful thinking to control the temperature. But the anode for something like that would be fairly large, and more then likely, custom made, making it quite expensive." - great idea! i did thought about a similar setup but quickly abandoned it afterwards hehe.. seems to much sophisticated for a starting point. One thing to mention here - If you'd like, i have a friend that works in a factory that produces all types of industrial electrodes, from which i obtained my anodes for a rediculous price, i can ask him for some setup as such.. If you'd like, just let me know. "Thats what so great with WSM's bloggposts. They actually make (well, some) sense. I'm using a lot of "wait and see", and hope that he gets around to them LD anodes at some point." - No doubt! well, that makes us both eagerly wait for these anodes as well as the Platinum ones to be tested by him! WSM - No mean to rush.. Hi barzn, "The biggest difficulty is calculating the surface area of the anode mesh. Fortunately, with the MMO and to some degree the LD, one can assume the surface area to be the same as flat sheet anodes due to the increased surface area of the coatings on a microscopic level. With platinized titanium, smooth surfaces have less surface area than a dull (uneven) surface." - as i wrote for MrB, i figured it will be similar to a solid plate. Thanks! "The 2" by 3" anode equals 38.7 cm2 (multiply each square inch by 6.45 to get square centimeters) and if only one cathode is used at 0.3A per cm2 then the current demand is 11.61A maximum (and double that if two cathodes surround the anode). If lower current is used, less stresses on the anode will result. Also, regarding platinized anodes, lower temperatures (30oC) give higher CE's (90%+) than higher temperatures do. Industry uses cooling water running through cathode plates to keep the cell temperature in the desired range." - This is what i was missing about the anodes, most helpful information so far, Thanks alot! I've found that solid plate, CP titanium cathodes work best in my experiments, rather than mesh. It's also less expensive than mesh." - i actually have them as solid plates and not as mesh, in the same size as my anodes. I'm not sure what CP grade i have, but it's unalloyed, so it's somewhere between grade 1 to 4. "Also, the voltage is usually between 6.2-6.8 Vdc in industrial setups using platinum anodes." - that is regarding electrolysis of chlorate or perchlorate? I was told that optimal voltage for producing chlorate ranges in between 3-5Vdc while for perchlorate at about 7Vdc. Also, What is the changes needed for the making of the perchlorate ion, rather than chlorate, in terms of electricity (Voltage & Amps)? WSM I guess i'm left with two more questions.. How to calculate the volume of electrolyte to be used, and what are the changes for the making of perchlorate, especially in terms of voltage and amps, but also regarding other elements of the cell. Thank you both for the very usefull help! Keep it up!
WSM Posted March 15, 2015 Posted March 15, 2015 (edited) An interesting discovery in my perchlorate research is that a properly running perchlorate cell doesn't pump out ozone! Most amateurs treat a perchlorate cell like a chlorate cell and overload the anode with too much current. My suspicion is that a lightly loaded LD anode will make the perchlorate without the ozone production (platinum, too). We'll see... WSM Edited March 15, 2015 by WSM
WSM Posted March 15, 2015 Posted March 15, 2015 I've found that solid plate, CP titanium cathodes work best in my experiments, rather than mesh. It's also less expensive than mesh." - i actually have them as solid plates and not as mesh, in the same size as my anodes. I'm not sure what CP grade i have, but it's unalloyed, so it's somewhere between grade 1 to 4. "Also, the voltage is usually between 6.2-6.8 Vdc in industrial setups using platinum anodes." - that is regarding electrolysis of chlorate or perchlorate? I was told that optimal voltage for producing chlorate ranges in between 3-5Vdc while for perchlorate at about 7Vdc. Also, What is the changes needed for the making of the perchlorate ion, rather than chlorate, in terms of electricity (Voltage & Amps)? I guess i'm left with two more questions.. How to calculate the volume of electrolyte to be used, and what are the changes for the making of perchlorate, especially in terms of voltage and amps, but also regarding other elements of the cell. Thank you both for the very usefull help! Keep it up! Any of the CP grades will work for us and avoid unwanted ions in the cell. 6.2-6.8 Vdc is for platinum anodes in perchlorate cells. Chlorate cells in industry use 3.6 Vdc, but anywhere from 2.5-5.5 Vdc seems to work in chlorate cells using MMO anodes. Current usage is determined by the surface area of the anode and depends on the particular anode and cell parameters. The volume of the cell depends on how you set it up. Smaller cells are easier to deal with and run in shorter time periods; larger cells are more difficult to deal with due to the sheer amounts of toxic materials you're dealing with. As a rule of thumb, fill the cell tank about 80% and leave an air gap above the cell electrolyte to allow the hydrogen bubbles to pop without encouraging the "salt creep" problem which tries to eat your electrical connections. I suspect a 5.0-6.0 Vdc perchlorate cell using an LD anode would work well with 0.2A/cm2 of anode area will work well and I need to prove this for myself before I can state it as fact. WSM
barzn Posted March 19, 2015 Posted March 19, 2015 Any of the CP grades will work for us and avoid unwanted ions in the cell. 6.2-6.8 Vdc is for platinum anodes in perchlorate cells. Chlorate cells in industry use 3.6 Vdc, but anywhere from 2.5-5.5 Vdc seems to work in chlorate cells using MMO anodes. Current usage is determined by the surface area of the anode and depends on the particular anode and cell parameters. The volume of the cell depends on how you set it up. Smaller cells are easier to deal with and run in shorter time periods; larger cells are more difficult to deal with due to the sheer amounts of toxic materials you're dealing with. As a rule of thumb, fill the cell tank about 80% and leave an air gap above the cell electrolyte to allow the hydrogen bubbles to pop without encouraging the "salt creep" problem which tries to eat your electrical connections. I suspect a 5.0-6.0 Vdc perchlorate cell using an LD anode would work well with 0.2A/cm2 of anode area will work well and I need to prove this for myself before I can state it as fact. WSM This is just all the information i was missing regarding voltage and current, best explained!WSM - You just have an answer for every sort of question! You have such a great knowledege and it's a great to have you here!I'm going to set up my cell(s) soon and start from scratch all the way to K Chlorate and Perchlorate.I will document and film the whole process thoroughly, Regarding all the principles of the process that i can implement, with different setups.I can say in advance that It's more of a learning and experiment for myself, Rather than making points for others, but i hope someone could find use for it.I will post it here for anyone's reference, in about a month or so.I'm looking forward for your experiments results, it surely will give me and everyone here an inspiration.Thanks for all your help!
carbonhalo Posted March 19, 2015 Posted March 19, 2015 I'd like to make some chlorate cells but my house batteries wouldn't cope. I have a number of spare solar panels but I'll have to rig a circuit so my old set of house batteries would run a low current through the cells at night to prevent electrode destruction.I wonder how little night current I could get away with.
Arthur Posted March 20, 2015 Posted March 20, 2015 Having thought solar might be a free means of making chlorate for a while. You could use solar to make 5v during daylight hours , and remove the electrodes at dusk, repeating daily. OR you could use a cell above a dump tank and get the liquor into the cell by solar (so at first light) and let it fall back after sundown. The big issue being keeping the liquor warm -the chlorate reaction is better done at 40+C Certainly look at the sodium salts, they stay in solution when cool. Potassium salts will precipitate out when cool and will clog pipes
carbonhalo Posted March 21, 2015 Posted March 21, 2015 I had thought of the dump tank/pump solution...a shallow cell and leak rate similar to the pump...and having a fluid level switch for the pump. ..or spring loaded electrodes with a motor drive to push them into the liquor (seemed very hard to proof against corrosion)I thought having a maintenance current would be the easiest solution. I was thinking 10mA would be a good starting point.I suppose there would need to be a heating element to return the cell to operating temperature in the morning.
WSM Posted March 21, 2015 Posted March 21, 2015 (edited) I had thought of the dump tank/pump solution...a shallow cell and leak rate similar to the pump...and having a fluid level switch for the pump. ..or spring loaded electrodes with a motor drive to push them into the liquor (seemed very hard to proof against corrosion)I thought having a maintenance current would be the easiest solution. I was thinking 10mA would be a good starting point.I suppose there would need to be a heating element to return the cell to operating temperature in the morning. The simplest system like this that I've heard of involved pumping the electrolyte solution from a low level reservoir up to a reaction chamber with the electrodes, and back again. If the power failed, the electrolyte drained back into the reservoir and the electrodes were left "high and dry". When the power came back on, everything returned to normal. The idea of heating the electrolyte may be unnecessary because after restarting, the system will come back up to temperature on its own (probably in fairly short order). WSM Edited March 21, 2015 by WSM
WSM Posted March 21, 2015 Posted March 21, 2015 (edited) Speaking of my perchlorate experiments, I unearthed my oldest concept cell this morning. A lucky find at an industrial surplus store years ago, is a Pyrex "battery jar" which measures about 6" diameter by 12" tall (150mm x 300mm) with a flat bottom. Several years ago I made a PVC base and lid for this piece of glassware to protect it from damage. I've used soft silcone tubing as a gasket for the lid and I hope it helps keep things secure and protected. I still need to drill and tap threads into the lid for some compatible fittings for the anode, cathode, vent and thermal sensor. I hope to run my initial tests very soon. I plan to try the 2" wide by 6" long LD anode with matching CP titanium cathodes in this cell. I'm still scrambling to gather the required amount of lab grade sodium chlorate for the electrolyte in these initial tests. I'll post the results as soon as I have something to share. WSM Edited March 21, 2015 by WSM
MrB Posted March 22, 2015 Posted March 22, 2015 The simplest system like this that I've heard of involved pumping the electrolyte solution from a low level reservoir up to a reaction chamber with the electrodes, and back again. Sounds simple enough, but... What sort of pump would manage the flow needed, and not be a contaminant in the system?B!
Arthur Posted March 22, 2015 Posted March 22, 2015 Pump up to a cell(with an overflow) with a magnetically coupled pump, when the pump goes off the liquor falls back into the reservoir through the stationary pump.
MrB Posted March 22, 2015 Posted March 22, 2015 Pump up to a cell(with an overflow) with a magnetically coupled pump, when the pump goes off the liquor falls back into the reservoir through the stationary pump. This describes most common pumps, but i'm quite certain some materials are less then ideal to include in our systems. I'm thinking the steel housing ones are a lost cause. So were looking at "plastic" ones. Something like an aquarium pump, might get a shorter lifespan from the heat, but can be had with ceramic "bearing" surfaces. But the magnet still remains in the system, and i'm not sure if they are up for that...Aquarium pumps would be a good choice for the range of flow as well, but... What good is that if the carbon rich plastic cant deal with the environment.B!
carbonhalo Posted March 22, 2015 Posted March 22, 2015 what about a peristaltic pump?... then you can choose the tubing material.
WSM Posted March 22, 2015 Posted March 22, 2015 (edited) This describes most common pumps, but i'm quite certain some materials are less then ideal to include in our systems. I'm thinking the steel housing ones are a lost cause. So were looking at "plastic" ones. Something like an aquarium pump, might get a shorter lifespan from the heat, but can be had with ceramic "bearing" surfaces. But the magnet still remains in the system, and i'm not sure if they are up for that...Aquarium pumps would be a good choice for the range of flow as well, but... What good is that if the carbon rich plastic cant deal with the environment.B! Arthur was describing the Iwaki magnetically coupled, chemical handling pumps. They're made to handle a wide variety of materials and run efficiently. All the moving parts are protected (in reinforced polymers) and the pumps move a lot of material, BUT, they are not self priming. WSM Edited March 22, 2015 by WSM
WSM Posted March 22, 2015 Posted March 22, 2015 (edited) what about a peristaltic pump?... then you can choose the tubing material. Paristaltic pumps are positive displacement and won't allow backflow. The variable options of pump speed, tubing material and size will allow excellent material handling and flow rate control. They are also self priming. WSM Edited March 22, 2015 by WSM
MrB Posted March 22, 2015 Posted March 22, 2015 Arthur was describing the Iwaki magnetically coupled, chemical handling pumps. They're made to handle a wide variety of materials and run efficiently. All the moving parts are protected (in reinforced polymers) and the pumps move a lot of material, BUT, they are not self priming. So the WMD, or MD series pumps. I have experience from those with... Aquarium use. They are a good choice for reliability even if not from a cost perspective. The glass filled polypropylene should be fairly inert, but what about the ceramic, and carbon filled plastic that makes up the bearing assembly?And these things really don't like solids. After the cell have been running for a day, and the flow shuts down, letting the liquor drain back through the pump, it will pull the days product with it back down in to the pump, and fill the housing. I'm not sure it will restart gently after that.B!
Arthur Posted March 22, 2015 Posted March 22, 2015 IN a sodium cell there is a better power efficiency, and very low chance of crystals forming (the chloride is least soluble, chlorate and perchlorate more and more soluble). If you can locate a breaker of photoprocessing equipment in your locality then Iwaki bellows pumps for topup and acid dosing should come cheaply and should handle any chem you are likely to need to use. There are also magnetically coupled recirculation pumps which are resistant enough to use on a "bucket cell basis" (last long enough to be useful but cheap enough to replace if needed). Remember that magnetically coupled pump is NOT normal (most are shaft driven and the shaft gland leaks) A Magnetic pump couples the motor and the rotor through a plastic wall by magnets. so choosing the ceramic bearing inner and the plastics of the rotor you can select it's cost and chemical resistances. If you are in the USA then WSM may share his contacts for ex-photolab parts.
MrB Posted March 22, 2015 Posted March 22, 2015 Remember that magnetically coupled pump is NOT normal (most are shaft driven and the shaft gland leaks) A Magnetic pump couples the motor and the rotor through a plastic wall by magnets. so choosing the ceramic bearing inner and the plastics of the rotor you can select it's cost and chemical resistances. Every pump i ever get in contact with is like this. The only exception i can come up with is pumps that have to be self priming, hydrofor pumps providing wellwater for houses. (And the self priming never works anyway.)Everything else, central heating circulation pumps, aquarium tech, pool equipment, and lab tech, is decoupled. Most of them use a stainless steel rod for the "bearing" and as such is unfit for these uses. I could check up on some Grundfos pumps, suited for saltwater applications, they might be stainless steel of a grade thats good enough for these purposes, but i have a feeling the flow-rates are a bit to much. And the housing / impeller is still some plastic with high carbon content. I guess we are side-tracking. The tip for photo-processing equipment as a source for a pump could come useful. Thanks.B!
Arthur Posted March 22, 2015 Posted March 22, 2015 Bellows pumps and mag coupled pumps from the photo industry can be suitable small enough for chlorate cells and suitably corrosion resistant, usually they have ceramic parts. As film processing is collapsing to zero there should be lots of used pumps on the market around most major towns.
WSM Posted March 22, 2015 Posted March 22, 2015 (edited) IN a sodium cell there is a better power efficiency, and very low chance of crystals forming (the chloride is least soluble, chlorate and perchlorate more and more soluble). If you can locate a breaker of photoprocessing equipment in your locality then Iwaki bellows pumps for topup and acid dosing should come cheaply and should handle any chem you are likely to need to use. There are also magnetically coupled recirculation pumps which are resistant enough to use on a "bucket cell basis" (last long enough to be useful but cheap enough to replace if needed). Remember that magnetically coupled pump is NOT normal (most are shaft driven and the shaft gland leaks) A Magnetic pump couples the motor and the rotor through a plastic wall by magnets. so choosing the ceramic bearing inner and the plastics of the rotor you can select it's cost and chemical resistances. If you are in the USA then WSM may share his contacts for ex-photolab parts. I'm not certain if, by the use of the word "breaker", Arthur means a "dismantler" of photofinishing equipment, or a typographical error for the word "broker" of used photofinishing equipment. Either way, photofinising is quickly going away (if it hasn't altogether disappeared), and a LOT of surplus materials from those machines are on the market (even new replacement parts). I found both types of the pumps Arthur is describing on eBay from a local supplier (so shipping was minimal). WSM Edited March 22, 2015 by WSM
WSM Posted March 22, 2015 Posted March 22, 2015 (edited) Every pump i ever get in contact with is like this. The only exception i can come up with is pumps that have to be self priming, hydrofor pumps providing wellwater for houses. (And the self priming never works anyway.)Everything else, central heating circulation pumps, aquarium tech, pool equipment, and lab tech, is decoupled. Most of them use a stainless steel rod for the "bearing" and as such is unfit for these uses. I could check up on some Grundfos pumps, suited for saltwater applications, they might be stainless steel of a grade thats good enough for these purposes, but i have a feeling the flow-rates are a bit to much. And the housing / impeller is still some plastic with high carbon content.I guess we are side-tracking. The tip for photo-processing equipment as a source for a pump could come useful. Thanks.B! If eveything else in such a pump will work for our purposes, the stainless steel could be replaced with titanium components. If you have a metal lathe or access to a machinist, CP grades of titanium machine similarly to mild steel. With careful attention to detail you could upgrade the pump to work in the harsher environment of a sodium chlorate or perchlorate system. The tougher part would be upgrading the polymer parts to compatible alternatives. Off the top of my head; PVC, CPVC, PVDF and PTFE are some that should hold up (in ascending order of cost). The best thing might be to research surplus chemical handling pumps and look for a good new or used one on eBay or some similar source (and shop for a reasonable price, too). I've collected many of the things I'm using over many years (if not decades) where patience and diligence are paying off. Unfortunately, my workshop area is a cluttered mess. I'm sure I'll have an amazing "virtual garage sale" one day in the future, but for now it's my collection of "really cool stuff". I'll switch gears when my age and health won't allow me to continue working on these types of projects. Then I'll start getting rid of it so my family won't have to deal with it. WSM Edited March 22, 2015 by WSM
Arthur Posted March 22, 2015 Posted March 22, 2015 I've just looked on ebay and found a twin iwaki bellows pump for $0,99 -ideal for pumping acid into a cell or pumping more brine into a continuous system. The reason for looking for pumps ex the photo processing industry is that they are suitable for strong acids, alkali and bleaching agents, so with some care should last the duration of a personal pyro hobby. (Especially if left washed out and dry between uses).
WSM Posted March 22, 2015 Posted March 22, 2015 (edited) I've just looked on ebay and found a twin iwaki bellows pump for $0,99 -ideal for pumping acid into a cell or pumping more brine into a continuous system. The reason for looking for pumps ex the photo processing industry is that they are suitable for strong acids, alkali and bleaching agents, so with some care should last the duration of a personal pyro hobby. (Especially if left washed out and dry between uses). When I received my Iwaki magnetically coupled pumps (the bellows pumps too, for that matter) from eBay purchases, they were contaminated with photofinishing chemicals. To test them I connected them to electrical power (120 Vac, 60 Hz), and ran fresh water through them into a bucket till they were cleaned out (and smelled better). I then dried them and stored them for future use. They look very useful and I'm glad to have them. WSM Edited March 22, 2015 by WSM
MrB Posted March 22, 2015 Posted March 22, 2015 Bellows pumps seams to be low flow membrane pumps, with a pair of 1-way valves. Didn't investigate it, it's just what i understand from a glance on the pictures.Should work fine as long as the valves doesn't get messed up by solids. For a system that needs to drain when the power shuts of, thats not ideal. But the life-expectancy of iwaki pumps in general is next to legendary, so i think they would outlive most hobby users.B!
WSM Posted March 22, 2015 Posted March 22, 2015 (edited) Bellows pumps seams to be (1) low flow membrane pumps, with a pair of 1-way valves. Didn't investigate it, it's just what i understand from a glance on the pictures.Should work fine (2) as long as the valves doesn't get messed up by solids. For a system that needs to drain when the power shuts of, thats not ideal. But the life-expectancy of iwaki pumps in general is next to legendary, so i think they would outlive most hobby users.B! Notes: 1) Pretty much. The main downside is they pulse during operation (the flow is in spurts rather than continuous). 2) With sodium solutions and KCl solution, no problem. With potassium chlorate electrolyte, yes; there may be crystallizing problems. These pumps are not the type to use for a self-draining system (during power outages). Iwaki pumps are amazing, and astoundingly quiet in operation. WSM Edited March 22, 2015 by WSM
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