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Quick question on "old" ano method......

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  • #31
    Yes, the distance does effect the circuit conductance, which is what the PS sees. Do what you can do.


    • #32
      Regarding my combination agitation / cooling system:

      Rereading the threads by Neilfj and NeoMoses on the subject (agitation system) will help. Do a search.

      The pump is a Little Giant 3-MDX, go look on their website These are acid rated smaller industrial models, they will hold up to constant use. These are not self priming. I dealt with this by holding the tank off of the floor about 2 feet with an aluminum stand, and cutting a drain hole in the bottom of the tank. The drain is set up with 1/2 NPT PVC bulkhead fittings. This goes to a polypropylene barbed fitting for the 5/8" ID plastic tubing that both the pump and chiller use. The "Tank" is a 7 gal. plastic office waste paper basket from Staples, its cheap and the form factor is perfect for my purposes. Draining from the bottom and placing the tank above the pump solves the self priming issue by use of gravity.

      The plumbing is like this; electrolyte is sucked out of the tank from the bottom drain, and routed to the intake on the pump. The pump output goes to the chiller input. The chiller output goes back into the tank via a Tee, which splits its input to both ends of a 3/8" ID PVC pipe with the agitation holes drilled in it. Like in NeoMoses' method, tank corners are turned with PVC elbows.

      The chiller is a 1/4 HP unit purchased from Its an ordinary aquarium chiller for salt water tanks. Mine has its thermostat modified to go down to 32 deg. F.. If you don't intend to do Hardcoat, you don't need 32 degree F. electrolyte, and you can get these chillers from numerous suppliers, shop around. You do want one with a titanium heat exchanger. Sid's setup is probably too big for a 1/4 HP unit, he may need a 1/2 or 1 HP unit.

      I did add some niceties like quick release connectors between units, and a 2 way valve before the Tee. The valve allows me to quickly and neatly pump the electrolyte out of the tank into another container, since I don't anodize on a routine basis. It also makes flushing the system out with water easy to do.

      You may have trouble finding some of the plumbing fittings, McMaster-Carr has most everything.

      I was paranoid at first about something failing and squirting electrolyte all over. It didn't happen. I'm a crappy plumber, if I could make this thing liquid tight without undue effort anyone can. Do your testing with plain water first, of course.


      • #33
        so nothing in those pumps or chillers are anything but Ti or plastic(that the fluid contacts)? Where is that pump located on the little giant site?

        I remember that somebody had a problem with grease coming out of the pump and then I believe the pump burned up.......was that just a fluke?


        • #34
          Look under magnetic drive pumps. There is a chemical resistance chart, and all components and what they're made of is listed in the data sheets.
          The 10% sulfuric acid line on the chart will cover all usable concentrations of anodizing electrolyte.

          I think it was M_D (?) who initially had some problems, I believe he now has things sorted out. These pumps can be quickly disassembled without tools for cleaning. There was some silicone (?) grease inside as a preservative, I cleaned it out with a paper towel. You are not supposed to run these pumps dry for any length of time, that will damage them.


          • #35
            The first pump I used was one just like NeoMoses used. I ran it for a little while, and had problems with the anodizing that I assumed was from the grease. So I cleaned it all out, and it ate itself up shortly after that.

            Then I bought a Little Giant Pump similar to the one Fibergeek mentioned. I cleaned the grease out of it before the first use and it has run hundreds of hour so far. I haven't inspected it for a while, but last time I did it looked good and didn't appear to be wearing excessively.


            • #36
              looks like the orings in those little giant pumps will be effected by the acid, and the ceramagnet isnt listed under the 0-10% sulfuric acid micture, but has a low rating under the higher acid mixture.

              My ano tank is 15 gallon, will that pump be enough?


              • #37
                This is the one I have, and it works well in a 55 gallong tank.

                Little Giant Chemical pump
                3-MD-HC series
                1/12 HP Open Fan cooled
                Intermittent Liquid Temp: 200F
                Specific gravity: 1.1
                Intake: 3/4 FNPT
                Discharge: 1/2 MNPT
                Glass-filled Ryton Magnet Housing
                Glass-filled Ryton Volute
                Glass-filled Ryton Impeller
                Viton O-ring
                Ceramic Thrust Washers
                Ceramic Shaft
                Weight (lbs) 8.8

                They have several grades, you need one for high corrosives. I think I paid about $150 each at Grainer. I found a cheaper place the other day, about $135-$140 if I remember correctly, but I can't seem to find it now.


                • #38
                  I imagine that would be a touch much for my tank then, dont you think? They make so many models.....guess ill have to read up and see what the differences are


                  • #39
                    I forgot to mention that I used it in a 15 gallon tank and it worked fine.


                    • #40
                      So it wasnt too much for the 15gallon? I dont really want acid splashin everywhere.

                      Fibergeek- You have any examples of 2000 series ano curve? How will it act when it hits PAR, start to rise?


                      • #41
                        You find that its not hard to set the angle of the holes so that the jets of electrolyte don't break the surface. I'm recirculating 5 gallons at 420 GPH that's 7 GPM, it takes 43 seconds to cycle all of my electrolyte. The surface looks dead calm, but 1 inch below and to the bottom its really moving. I have no bubbles sticking to the work or the cathode ever.

                        I have many anodization curves for 1100, 2024, 6061, and 7075, at ASFs from LCD through 21 ASF. I'm not at liberty to share them until early July.

                        I'll cheat a little and just verbally describe a few.

                        These were 90 minute anodizations to grow "Type II 1/2" coatings up to 3 mils. thick, not what you would want.

                        18 ASF, 70.4 deg. F. 1:1 electrolyte, very accurately instrumented.

                        2024 started (+3 minutes) at 1.22 Ohms/sq,ft., and gently sloped downward to 1.05 Ohms/ sq.ft. at +90 minutes. The final coating thickness was 17um (0.7 mils) there were signs of dissolution (chalky residue) but dyeing was fine.

                        Contrast this to 6061; same ASF, temp., time, and electrolyte:

                        This rose rapidly to 1.10 Ohms/sq.ft. at +5 min. they continued to rise at a slower rate to 1.62 Ohms/sq.ft at +90 min. The thickness was 70um (2.75 mils.) no dissolution signs, dyeing also excellent.

                        I didn't provide voltages as these would be meaningless since the size of your work is so different than mine. You can calculate what the voltages would be for a given surface area.

                        PAR was not evident, I have found out with a lot of testing that it only works with weak electrolyte, and is most visible at LCD ASF ranges, it will not be visible at all with racking.


                        • #42
                          Re: Acid Concentrations

                          Can some one please translate the 1:3 or 10% or grams per litre acid measurements to something I can easily measure like specific gravity. I have used my acid bath for quite some time and I know I've lost a lot of water through evaporation. Knowing that the original mixture was 3:1 "battery acid" - which I assume is a variable itself - doesn't help me now and I don't have any sofisticated equipment to measure grams/litre. Can someone relate these measurements to specific gravity which anyone can measure with a simple $3.00 car battery hydrometer? If there is a conversion formula I'd appreciate knowing it since I'd like to experiment with diffferent concentrations in my process in the future.



                          • #43
                            Re: Quick question on "old" ano method......

                            The easiest cheapest way is to measure out your electrolyte and bring the volume back to the original level mixed with distilled or RO water. The only other way to check acid concentration is titration or mix a fresh batch. I know it's not what you wanted to hear but I don't know of any other ways.


                            • #44
                              Re: Quick question on "old" ano method......

                              Actually this wasn't difficult at all. Sorry I asked.

                              I made two very small new batches of acid to the 3:1 and 2:1 ratios specified by Caswell for thier old and new LCD processes. "Battery acid" as I find out now is pretty standard at 19.2% by volume, 35% by weight H2SO4.

                              I then measured the specific gravity (s.g.) of the two samples with a cheap Hydrometer available at any auto supply place.

                              Just so eveyone is aware, the Caswell LCD solution which is a 3:1 mixture of battery acid and water and is apparently 4.8% by volume H2SO4 measures about 1075 s.g..
                              The original Caswell solution which I gather was 6.4% H2SO4 by volume and a 2:1 water acid measures 1100 s.g.

                              To back up these test results I found the data on the internet for sulphuric acid from Sulco Chemicals, an acid manufacturer. They listed various acid percentages against their s.g. The s.g measurements I made coresponed pretty closely to the percentages I new I had and their data.

                              Now it was a simple matter of returning my acid to the 1075 s.g by adding water which means it is back to the LCD spec of 4.8% by volume and 3:1 mixture.

                              Simple and cheap.



                              • #45
                                Re: Quick question on "old" ano method......

                                I didn't mean to offend. I had asked the same question when I first started and was told it wasn't an accurate way to check acid concentration. I am fixing to mix more acid for a larger tank and I'll have to check out the s.g. of different ratios.