Recirc without a pump

[bashworth]

I am planning to use an RO system for the first time this season. I have a single XLE 4040 membrane & am looking for some advice on setting up a recirc loop without using a pump - i.e. I have a feedpump to move the sap from my storage tank and a Procon Series 4 pump to pressurize the membrane. I am wondering if anyone has operated a recirc loop using just needle valves, check valves, rotometers and T's without the use of a third pump? Any advice or schematics would be appreciated.

[wiam]

That is how my old Memteck was made

[maple flats]

That's also how my Ray Gingerich RO is made. No check valves, just a recirc loop after the membranes, back to the HP pump inlet controlled by one needle valve.

[BreezyHill]

That is a valid design, I will dig out my old Memtek book to see if there is a schematic in it.
If you are looking to make a simple system with one membrane I would suggest to simply recirc using a batch system.

Batching is less costly, and easier to design and setup.
To run the evaporator while ROing the sap; simply pull off to the evap as needed while the rest of the sap is concentrating. When you have reached your desired concentrate level you are done.

My next system will be setup this way.
I have a retired bulk tank that has a functioning cooling system that will be my new evaporator tank.
Ro will be connected to collection tank to transfer to the evap tank and to the evap tank. Simple float valve connected to solenoid valves to concentrate the evap tank when the collect tank is not at risk of overflowing.

I have to have a system that will run on automatic so the wife or next generation does not have to babysit the RO. $200 of floats, valves and switches makes life so much easier. Plan to have the new system up for operation in two years... or when my Memtek decides to retire itself. It is a great unit but it is really noisy.

Best wishes!

[Clinkis]

I had the same question that I asked on the thread below. If you read through it there is an explanation as well as a photo with description of how it works.

http://mapletrader.com/community/showthread.php?22468-Single-XLE-4040-Build

[Wanabe1972]

The way I have my RO setup is plumbed with 2 manifolds. One manifold with valves from my permeate tank, my truck tank and my concentrate tank all running to the feed pump. the other manifold is after the feed pump and before the pressure pump. This manifold has valves to the head tank, wash tank and the HP pump and to waste outside. I did this so I could use the same feed pump to run the RO, feed the evaporator and get rid of any waste water. My plan for running the RO was to concentrate from the truck tank until everything is either into the concentrate or permeate tank then close the truck tank valve off and open the concentrate tank and run that right back through the RO to circulate from the tank through the RO and back to the tank. Will this work like this?

[bashworth]

Thanks to all who responded to this thread. Using your advice I went ahead and added the recirc loop to my single XLE 4040 system. Since winter refuses to back off yet in Eastern Ontario, where my sugar bush is located, I have not had the opportunity to test it with sap yet but I did run some water from my well through it and things seemed to work alright - except for the incideous leaks... I ended up with a similar setup to the one shown by Tunbridge Dave forwarded by Clinkis using a tee, check valve, needle valve and ball valve running back to the input side of my high pressure pump. In my test I had the pressure up to about 180 psi & was getting about 2.5 gallons per minute coming out of the concentrate hose. Since there was no sugar in the water I was only able to measure the before and after TDS and saw an increase of about 3 to 4 times in the concentrate. I will play with this more to fine tune the pressure setting when I finally get this thing running in my sugarbush.

Thanks for all the advice.

Happy sugaring!

[Clinkis]

Hey Bashworth. I'm doing research on building the exact RO (hence why I was asking questions on thread I forwarded to you). I'm also in Ontario. Just curious where you got your parts from. Suppliers seem to be few and far between in Canada compared to US. Also, if you don't kind me asking, what you figured you spent on it? Would love to see some pics of the finished product. Had originally planned on building it in time for this season but a broken ankle had me sidelined for a while so Its now in the plans for next year?