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Better to start with a needle valve, or a flow restrictor? I'm planning on using a single 100gpd membrane to start since I only have 10 taps right now. How to size the restrictor?
I found this site... http://www.purewaterproducts.com/art...ow-restrictors
But I'm sure that's for normal tap water temperatures, and not near freezing temperature sap. That will reduce the flow rate, and then how to calculate the proper restrictor? I'm liking the idea of the restrictor vs babysitting a needle valve.
Also, can you adjust the needle valve by monitoring pressures in the system somewhere, or are you always measuring flow rates instead?
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Brett:
Thanks for an excellent overview of a small scale RO system.
I'm pondering something like this for next year.
Can you provide the type of membrane and membrane housing you are using and where they can be found?
thanks
Mark
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Quote:
Originally Posted by
troynh
Thanks Tim.
Mark
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This was very helpful. Thanks guys. Wish I found this thread before I started one of my own.
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Wobbletop:
With 10 taps a single membrane will do fine. You will just keep recirculating it back into your feed tank and will eventually get up to a 6+ concentrate level. You will try for a 1 part permeate to 3 or 4 parts concentrate. This will keep the membrane from fouling and work much better. You can use a needle valve it will be fine since you will not be creating much back pressure or a flow restrictor. The smallest I found was a 150ml size you might want to go a little larger for recirculating though.
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Hodorskib, I built an RO to your specks , I was getting 10 gph . My sap was mostly 1 1/2 % with some from sugar maples at 2 1/2%. On the 1 1/2 % I was getting 6% concentrate , the 2 1/2 %was higher. I used a 150 gph flow restrictor. Would I get a higher % concentrate with a pressure flow valve. Also I am a little confused about the soap to clean the membranes. Or do you just use the Peroxide ?
I greatly appreciate all the information you provided. It was an easy build and saved a ton of time and wood.
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Glad it worked out for you. The flow restrictor I tried this year gave me the same results around 6% so I went back to the needle valve. However, another guy who built a system a few years ago sent me a link for a pressure bypass valve and after using it for the last week or so of my season it was worth the extra money. Here is a link for it:
http://www.sprayerdepot.com/Shop-by-...ves/AA11014300
This allows for much better control and the ability to go to 8% and unlike a needle valve once you set it you don't need to keep adjusting.
As for cleaning I will be updating the website as soon as I get a chance but this year I plugged my membranes really bad and needed to think about a better way of keeping them clean. Here is what I came up with after talking to others with similar systems: I will be doing this once a week
1. Change your water filter
2. Open the membrane housings and dump out any liquid in the top - there is usually some slime and gunk especially toward the end of the season
3. Flush with permeate for 20-30 minutes
4. Fill a 5 gallon bucket with warm water and put 1 quart of hydrogen peroxide in
5. Run that through the system recirculating it back into the bucket (just take your concentrate and permeate lines and put in the bucket) and let run for 1 hour
6. Replace the water filter and flush with permeate for 20-30 minutes (leave the water filter in place you will use it for the next run)
This is also what I did at the end of my season then wrapped the membranes in plastic wrap put in a zip lock bag and they are in my beer fridge for next year.
Let me know if you have any other questions: huu133@gmail.com
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hi..can you explain the relationship between the pressure valve and the % of the concentrate? How does one affect the other?
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You need to install something to create back pressure on the concentrate line. It can be a needle valve, flow restrictor or by-pass valve. This is what forces the water through the membranes. The more back pressure the more water is removed which gives you a higher concentrate. However, the higher the concentrate the less gallons per hour you can process so you have to play around a little to see what works for you. For me the balance this year was between 7 and 7.5% and with 6 membranes I was able to process 10 gallons per hour when the sap was around 50 degrees and 6-7 when below 40 degrees. Hope this makes sense.
