Help me Design our RO

[BRL]

So we finished up our season last night and we are looking ahead to next year. I would like to build an RO and want to build it big enough so we don't out grow it to quickly. Right now we have 315 taps most on buckets and our best day was 275 gallons. Next year we are going to add 3/16" tubing and we should 300-350 on tubing and 50-60 on buckets. We have good slope for the tubing so we should get the most out of it. Now for the RO, do we go with 2 4" membranes in series with a high GPH pump or 1 8" membrane with a high GPH pump. Which one will get us a high % concentrate and would one burn through 500-600 gallons a day quicker then the other. If you have pump, parts, membrane suggestions I'm all ears. Thanks Brian

[bowhunter]

Your question depends on three things: How fast you want to run up 600 gallons of sap, How much money you have and how much above 600 gallons a day you think you'll get. An 8 inch is larger than two 4 inches so the 8 inch has more capacity, but the pump, motor, membrane and membrane housing for an 8 inch are pretty expensive relative to a 4 inch.

You can build a system with one 4 x 40 inch Axeon NF3 or Filmtech NF270 membrane, a 5 micron sediment filter and a 1 Hp ProCon pump (no relief valve) capable of 265 GPH. The unit will be capable of removing 70% of the water from cold 2% sap at 80 GPH and anywhere from 175 psi to 250 psi depending on how dirty the member gets. It will make about 24 GPH of concentrate which is 6.5 -7.5% sugar. This size unit is simple to build and operate. You may not need a booster pump for the 265 GPH Procon if you can elevate the sap feed tank a foot or so about the level of the pump to make sure it's flooded. You use a needle valve to control the pressure on the unit by recirculating concentrate back to the pump suction and a second needle valve to control the flow of concentrate. You will need a pressure gauge and two flow meters: one for the net concentrate out of the unit after the recirculation take off and one on the permeate. The unit can be expanded about 30% by adding a second membrane of the same size in series.

[mellondome]

A quick search of this site and the other one will give you lots of step by step builds for a 4x40 ro ( plenty big enough for 400 taps).

As a side note, Always use a supply pump to push through your 5micron filter to the pressure pump. It is a small investment that will save lots of headaches and additional money down the road when you cavitate and destroy the procon because the filter restricted the flow.

[Flat Lander Sugaring]

Tech at fluid o tech told me i could gravity feed their pump, they fixed it for free after it grenaded and filled the feed side of my XLE full of small graphite particles.
like mellondome said use a feed pump from TSC/Homedepot 160 dollars no worries

[bowhunter]

While I agree a booster pump may be a good idea in some cases, I'm not a big fan for these homemade units when you can elevate the sap tank. It is no guarantee that you will have good flow to your pressure pump. The filter can still plug, the booster pump can fail or the supply tank can go dry and the booster pump won't prevent these things from happening. If you're concerned add a pressure switch to the pump suction and add low pressure pressure gauges before and after the filter. That way the filter can be changed when it gets dirty. The ProCon pump is probably less expensive than the booster pump and motor so you could afford to keep a spare pump. And you don't have to run the additional motor. You want these systems to be as simple as possible.

[Flat Lander Sugaring]

While I agree a booster pump may be a good idea in some cases, I'm not a big fan for these homemade units when you can elevate the sap tank. It is no guarantee that you will have good flow to your pressure pump. The filter can still plug, the booster pump can fail or the supply tank can go dry and the booster pump won't prevent these things from happening. If you're concerned add a pressure switch to the pump suction and add low pressure pressure gauges before and after the filter. That way the filter can be changed when it gets dirty. The ProCon pump is probably less expensive than the booster pump and motor so you could afford to keep a spare pump. And you don't have to run the additional motor. You want these systems to be as simple as possible.

new pressure pump from Fluid o tech $135

most definitely add pressure switches like Bowhunter says, I have one each for my pumps, the HP pump shuts down around 30 psi and the feed pump shuts down around 15

[BRL]

Thanks for the replys everyone. I think i have decided to go with 2 4x40 membranes. I will run a booster pump (probably a 1hp Grunfos). Next question do I run the membranes parallel with a 330 GPH procon pump or in series with a 480 GPH pump? How do the big guys pipe there recirc? I have looked at build threads but can't find anything on recirc piping. I'm going to start collecting parts. I have also decided to control it with a PLC. So in the future I'll be able to start the RO from work so when I get home I can start boiling. There will be built in safety's so if something goes wrong it will shut down. Thanks Brian

[bowhunter]

I'll try to answer several of your questions from my perspective and you can take it for what it's worth. You really need to decide how much sap you want to process, how fast and what sugar concentration before you decide on pump and membrane size. Otherwise you could be very disappointed in the performance. Not many people on the forum run this way, but I really like to run the RO at the same rate as the evaporator so I don't have to store concentrate and I don't have to run concentrate through my feed filter. Stored concentrate gets slimy in a hurry and will foul you filter and membrane quickly.

If you run the 2 4X40's in parallel the 330 GPH ProCon really isn't big enough to meet the minimum flow requirements for the membrane. All membranes have maximum and minimum flows required for concentrate and total sap. In sap service a 4 inch membrane requires about 4 GPM of concentrate flow out to achieve optimum life and performance. For two 4 inch membranes that's about 480 gallons per hour. If you run at the recommended target of 15% recovery or removing 15% of the water in the membrane that means you need a pump capable of 565 GPH or 9.5 GPM.

The recirculation is simple. Don't make it complicated. On the concentrate flow out of the membrane(s) install a tee. The each leg of the tee goes to a needle valve. One controls the flow of concentrate out of the unit. The other needle valve controls the recirculation flow. The recirculation ties into the pump suction between the sediment filter and the pump inlet. After the concentrate flow out needle valve install a flow meter so you know how much concentrate you're making for the evaporator. If you send me a private message with your e-mail address I'll send you a very simple sketch showing the relationship among the components.

You really don't need to start your RO more than 5 minutes before you light off the evaporator unless the evaporator is empty. Your RO will come right up to operating conditions in just a minute or two.