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Thread: Prototype system

  1. #16
    DIYer, not in the trades LLigetfa's Avatar
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    I know you stated that this thread is for "people in here that have extensive field knowledge" and I am far from fitting that description but humor me if you will cuz I want to understand. Why would not the underbedding have kept the resin out of the bottom screen?

  2. #17
    That's all folks! Gary Slusser's Avatar
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    My guess is that he didn't have any underbedding in the softener.
    Gary Slusser Retired (= out of business)
    Click Here to learn how to correctly size or program a water softener.
    CAUTION, as of Nov 12 2013 all YouTube videos showing how to rebuild a Clack valve have an error in them that can cause damage.

  3. #18
    Water systems designer, R&D ditttohead's Avatar
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    Quote Originally Posted by LLigetfa View Post
    I know you stated that this thread is for "people in here that have extensive field knowledge" and I am far from fitting that description but humor me if you will cuz I want to understand. Why would not the underbedding have kept the resin out of the bottom screen?
    Perfect question. The spider distributor cracked right at the top, and the underbedding was loaded to just barely cover the screen. When it cracked, it sucked in some garnet, and resin. I used the large spider distributor which is over 7" tall, plus the fact that it sits high in the bottom dome, it sits almost 9" hig, almost triple the height of a standard bottom screen. I designed the system to handle only 2 Cu. ft. of resin so I thought the additional height of the spider distributor would be fine especially since I was planning on a higher backwash rate than normal.

    The spider distributor is a great concept, but the percieved benefit and potential problems, and the extreme price make it difficult to recommend in a downflow system.

  4. #19
    Water systems designer, R&D ditttohead's Avatar
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    I finally fixed the picture, the final design has been working since January without a problem. I added in waste diversion based on TDS. The RO waste shares the same drain line which goes to irigation as well. I replaced my waste TDS monitor with a digital unit from HM Digital, and I added a 2 Cu. Ft. Post RO DI tank for my carwash and test sink. I have also added some more pressure gauges to see if there is any loss of flow through the system, so far, it is flawless. Obviously this is not exactly a marketable system but it does prove a few design ideas. It has no noticeable loss of flow through the medias with flow rates in excess of 15 PSI, and the backwash rate sharing through the different sized tanks works great with no loss of flow. The salt dilution is no issue condidering it only goes through an additional 10x22 tank prior to entering the softener tank.
    All in all, I like the design, and the water it produces is great.

  5. #20
    DIY Member ByteMe's Avatar
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    Hey Dittohead,

    You are doing what I have been thinking. I just moved into a rental, after I build a custom house (less than a year away) I want a water filtration system much like this. Would you be interested in helping/sharing with me to design such a system. I do not know yet what my water will be like (well/city,etc). I have just recently become interested in water filtration technology, so I am way behind your knowledge, but I love this topic from an engineering perspective.

    Feel free to post different systems/pictures of experimental systems you are involved with. Makes very interesting reading/learning.

    FYI; I am a corrosion engineer for a super major oil company.

  6. #21
    DIY Member ByteMe's Avatar
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    How much shipped to zip 79707 ? Really.

    Quote Originally Posted by ditttohead View Post
    Attachment 15371

    Here it is, installed and operational.

    Final equipment specifications:

    Stage 1: 10x22 with Garnet underbedding, 1/2 cu. ft. Turbidex. Reason, to eliminate the need for pre sediment filtration on my Reverse osmosis system. Turbidex filters down to 3-5 microns, more than adequate for any standard reverse osmosis.

    Stage 2: 14x47 with garnet underbedding, 2 cubic feet of softening resin, 10% crosslink. I also used a spider distributor for 14" tanks for better backwashing and distribution. I am not a fan of the spider distributors, but for this application I thought I would give them another try. I also slightly underfilled this tank since the backwash will slightly exceed the recommended 5 GPM per Sq. Ft. rating.

    Stage 3: 7x13 Garnet underbedding and 30# of KDF55, reason: Removal of heavy metals, and pre treatment of the GAC bed.

    Stage 4: 12x44 tank, garnet underbedding, 1.75 Cu. Ft. of CarbSorb. This GAC has been an amazing product, other than the difficulty in getting it to rinse down, this stuff is the nastiest, dirtiest carbon I have ever seen, it also works better than any we have tested.


    Ok, so who wants to order one?

  7. #22
    DIY Member ByteMe's Avatar
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    Thinking again after a Whataburger recharge. How are you figuring the tank diameter? The manufacturers seem to give a backwash rating of GPM as per cubic foot of resin? Are you using a cubic foot to mean a 12"x12" surface area or 144 square inches? Using the formula of pi times r squared to determine the surface area, a 10" diameter tank = 5" * 5" * 3.142 = 78.55 square inches. So 78.55" / 144" = 55% of the surface area. 55%* 15GPM = 8.25GPM.

    But then, does converting a cubic foot to surface area the correct way to figure this? It seems to me the only correct way to figure this is by contact time. You need the water in contact with the media a long enough time to let the media do its job. So now we would need to figure the flow rate of the water in a given amount of volume. I just don't understand how you would convert a 3D volume to a 2D area.


    Quote Originally Posted by ditttohead View Post
    Excellent observations for the backwash rates of the different media. This is more of an experiment on what can be done. I have adjusted all the tank diameters to "balance" tyhe backwash rates to their manufaturers recommended levels. The only one I am slightly off on is the water softener, I am slightly higher than the recommended 5 gpm per sq. ft. level, but I am also running a slightly higher than normal freeboard.

    The backwash rates are based on surafec areas.
    Micro-Z/turbidex requires 15 GPM per sq. ft, thus the 10" diameter tank 6-8 gpm
    Softeing resin requires 5 gpm per sq. ft, thus the 14" tank with a slightly lower resin level. 6 gpm
    KDF requires a 20-25 gpm per sq. ft backwash rate, thus the 7" tank. 6-7 gpm
    8x30 catalytic GAC requires a 8-10 GPM bsackwash rate, thus the 12 inch tank 6-8 gpm
    I will probalby use an 8 GPM flow control allowing the KDF to have the best possible chance of backwashing effectively. KDF only expands 10% at a 25 GPM per sq ft backwash rate. Most other medias have a 20-30% expansion rate You are definetly right about KDF being a pain.

    I feel KDF and Pyrolox are the 2 best modern medias available, they are also the two most difficult yo get to work right. They must be set up correctly to work as advertised and to last. The old blue system you see in the pictures above go for ten years and over 2 million gallons of water between KDF changeouts.

    The system will be designed with a downflow brine so excessive dilution of the brine will not occer going through just the Micr-Z tank. We regularly build units with a full 2 cubic feet of resin prior to the resin with no noticable or caculable changes in brine efficiency. If I move the softener tank to the end of the design which would be a more proper way to build this unit, I would definetly go upflow brining. Unfortunatel, I have been unable to come up with a good way to do that. The "off the shelf" tanks are not available with the proper openings.

    I really apreciate the input. It is helping me tremendously to find any bugs prior to building this unit.

  8. #23
    DIY Member ByteMe's Avatar
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    My next brainstorm. Why as cheap as microprocessors are, there is no excuse for not using them.

    My first question is where is the water meter turbine meter located? Is it able to measure all the water coming into the softener? If it can, why not use this to determine exactly how much water to put into the brine tank. I would think it would then also be possible to use a ratio from this to determine the same amount then pulled from the brine tank. This would eliminate unneeded time during these cycles. You could than also control the other steps (fast rinse, etc.) exactly. Why hasn't this been done?

    I also need to find out would much salt can be dissolved in potable water. I expect a number of factors such as temperature, TDS, etc. will effect this. Anyone got a formula for me?

    Is there an amount of contact time needed for the brine water to regenerate the resin? Many of the same factors would apply.

    It also seems this process NEEDS to be controlled by a microprocessor (to get anything close to being called efficient) , even if you had to add a few inputs such as TDS, ORP and temperature. I think I might have a new hobby project.
    Last edited by ByteMe; 11-11-2012 at 06:22 PM.

  9. #24
    Aspiring Old Fart, EE, computer & networking geek Mikey's Avatar
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    From Wikipedia, for pure water, for starters:
    Substance Formula 0C 10C 20C 30C 40C 50C 60C 70C 80C 90C 100C
    Sodium chloride NaCl 35.65 35.72 35.89 36.09 36.37 36.69 37.04 37.46 37.93 38.47 38.99
    Units of solubility are given in grams per 100 grams of water (g/100g). Conversion to pounds/gallon is left as an exercise for the student . Sorry about the formatting; the forum doesn't allow pretty formatting.

  10. #25
    Water systems designer, R&D ditttohead's Avatar
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    Some great questions and comments. First off, the backwash rates of most medias is determined by area, not volume. We calculate the square footage of a given bed area to determine the correct backwash rates. Density of media, specific gravity, surface area, water temperature etc all must be considered, but for the most part, the manufacturers of the media give us some fairly easy guidelines to follow.

    Example,

    Standard resin should be backwashed with 30% expansion. This would require approximately 10 GPM per square foot. Notice the chart below, it gives the temperature / bed expansion information allowing installers to easily adjust the system to the proper rates for the water temperature. Many problems have been caused over the years by companies not considering water temperatures in their equations. One of the largest restaurant supply companies hired me as a consultant about 20 years ago due to the high failure rate of their equipment, it was simply a lack of temperature compensation for their equipment. In the end we save them 100X my consulting fees in the first year.

    As to volumetric calculations, we do that for some media, but not most. It is done typically to simplify the equations, but... surface area and bed depth are the preferred equations.

    Example:

    Activated Alumina, it has a recommended flow rate of... we simplify that to no ore than 3 GPM per Cu. Ft, that is assuming a bed depth of 30-36".

    So many of these calculations rely on understanding the application. For a residential application, GAC and softening can typically be run at much higher flow rates than what the medias are technically supposed to be run at. On paper, GAC should not exceed 5 GPM per sq. ft., but we all run it at much higher flow rates, even when we are using poorly designed chlorine pellet systems. GAC can easily handle large quantities of Chlorine at high flow rates. On papaer, a common size 10x54 1.5 Cu. Ft. GAC system would have a manufacturer recommended maximum flow rate of 5 x 5 x 3.14 / 144 x 5 = 2.73 GPM. So a residential application that could see up to 10 GPM would technically need a 21" diameter tank system, or a 6 cu. ft. system. This is obviously not reasonable but on papaer it is the correct way to do it. We do many larger systems like this but they are for applications that require certifications to meet certain standards and the manufacturers literature must be followed.

    This is where field experience and expertise become very important. Softeners exceeding their maximum recommended flow rate on an rare occassion has no real long term negative affect, otherwise every house that has four bathrooms would require a 5 Cu. Ft. softener.

    I can definetly offer this system through one of our customers, we do not sell direct but we work with companies all over the world so it is definetly doable. I have had the best of luck with this design so far. Other than the failed Spider distributer, it is full proof so far.

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    Last edited by ditttohead; 11-12-2012 at 09:17 AM.

  11. #26
    DIY Member ByteMe's Avatar
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    Quote Originally Posted by ditttohead View Post
    Mixed media inside the same tank do not work well, no matter what people try to tell me. We have virtually every design and mnufacturers units here in house on our test benches and they all suffer similar issues. Media contact time is critical for the medias to remove contaminants from water to desired levels. The multi level systems with and without internal dividers are a very inexpensive way to get some of the affect of each media. GAC has a rated flow of 5 GPM per square foot with a minimum bed depth of 28 inches. This translates out to a service flow rate of less than 5 GPM for a 10x54 tank with the standard carbon load of 1.5 Cu. Ft. this is more of a technical issue than the real world. Medias tendto be massively underated as anybody who does chlorine injection will state that a 1 cubic foot carbon tank will remove virtually all of the chlorine even up to 10 gpm. This is true, but the carbon is being used for much more than just chlorine removal, it is being used for the removal of dissolved organic chemicals, etc.
    The KDF is also a contact time dependent media to function as it is rated. Even my 28 pound KDF tank has a technical rating of only 3 GPM. it will flow at over 20, but is it doing what it is rated to do? Of course not.

    My original design has the resin last, but that creates some problems with the lack of off the shelf parts to build it. my lat prototype is shown below, the tanks used for this system used to be reaidly available, the manufacturing has since moved to India and the cost and lead times make it prohibitive.

    I have substituted 10% resin to minimize the damage to the resin from Chlorine and Chloramine. I agree with you that the KDF and GAC should go first, but for this design, I had to sacrafice the order.
    What is your experience with that KDF canister that is retro fitted in a softener tank?

    In your above prototype, would it be a good idea to use a taller KDF tank and more resin (to increase contact time)?

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