Home Made RO

[twobears1224]

TEUCHTAR:could you give us some info on running your ro?? like,i've said before i,am new to them and i,am curious.
i,am wondering how you get one going,what pressures should be/run,ect.
i,ve looked at both membranes.the ones you used and the merlins.pricewise your better off going your way..those merlins are pricy in my opinion and alot smaller.
i have a fairly new submerible water pump.the waterline connection got busted because the pump wasn,t put in the casing right.i,am wondering if i could use it some how as the recirulation pump?? i read that CDL?? had theres inside the membrane casing and guys liked it that way.

delbert

[DanE.]

thanks for the pic's and info.last night i got on the membrane website which tube did you use?? i see they have a bunch of diffrent ones.

delbert

Hi, Would you be able to share this information. thanks Dan...

[KenWP]

there's no free lunch

if you need to pump the sap up 700 feet to get the pressure in the column,
forget about plumping up the hill because you'll already have the 300 psi pump to make it go up.

Would be hard pressed to find a hill around here anyways. Flat as a table around my place. You couldn't even run garvity lines here without being way up a tree on the far end.
I guess I need to invent a freezer unit and RO sap by freezeing it.

[twobears1224]

DAN:IS THIS WHAT YOUR LOOKING FOR?? formembranes.com

delbert

[DanE.]

Thanks. I'm going to have lot of RO operations quesitions in the next few weeks.


Dane

[Teuchtar]

Twobears:
To operate my RO, its just about like any other....
Connect the inlet hoses (one to sap tank, one to permeate). Use 3-way valve to select which tank.
Connect the discharge hoses (one to concentrate tank, one to permeate). Don't let the concentrate hose fall on the ground (another stupid mistake I made)
Back off the membrane pressure valve
Start the feed pump and flush out mostly all the air until the concentrate line is running "solid" water. Membranes don't like to RO bubbly sap.
Start the recirc pump to flush the membranes even more.
Close down the feed valve to limit the boost pump pressure surge
Start the HP boost pump and open the feed valve to allow it to prime (usually it starts up airlocked)
Close down the membrane pressure valve to raise pressure in the membranes up to 340 psi. Adjust as necessary to maintain concentrate/permeate balance the way you like.
Let 'er rip for four hours, then flush with permeate for 15 min or so, then back to concentrate.
Its less complicated than it sounds.

For the soap wash, I reconnect the sap line to a separate 15g tank. Set up about 10 gal of warm water at pH-11 using RO soap. Connect the concentrate hose back to that tank. Run the circ pumps to circulate the soap solution for 15 minutes at no pressure or until it feels warm. The pumps heat the soap, no need for additional heater elements. Then dump the hydroxide soap and rinse with plenty of permeate.

That recirc pump is exposed to the full 340 psi casing pressure. A common submersible pump might not like that kind of abuse, since the casing is intended to normally run between 0psi and 30-50 psi. The high pressure coming off the boost pump might rupture the casing, or fail the seal from high impeller thrust.
Not saying it won't work, but you'd need to evaluate the risk etc. Don't run the machine in your kitchen ! For the recirc pump I chose a really brutal dayton-grainger stainless process pump which I got as a new orphaned discontinued model. I chose a high flow (16 gpm if I remember) and 75 foot shutoff head, then a throttle valve to control the pressure drop down to 16psi differential, which Dow says is the max delta-p to get maximum flow through the membrane. Goulds make really nice pumps, and have models suitable for both the multistage boost, and the recirc. Grudfos also. Both are a bit spendy, but publish lots of good application help, and their dealers are very helpful with questions. Lowes/Homedepot/TSC are not in the same league.
Choosing the right pumps is a tricky process and it took me months to iterate the design. This machine uses 3 pumps back to back. The first pump is a procon gear pump who's flow doesn't vary much with pressure. The second pump is a multistage centrifugal pump whose flow is set by the first pump, and whose discharge pressure is a function of its flow-head curve. You need to obtain the flow head curve for each pump you use, make sure they're matched to the job. The Dow Filmtec application manual tells you the feed flow and pressure limits for the membrane you've chose. Then you need to make sure that the feed/discharge pressure of each pump steadily builds and doesn't drop below atmospheric when you start the pump, otherwise it gets airbound, and draws in all kinds of air at the seal. I put a throttle valve after the second pump to control its discharge pressure, and be able to bring the suction back above atmospheric to allow it to prime. The pressure gauge at each pump helps too understand whats going on, but not really necessary.
If I was to build RO's commercially (tempting !) I'd replace pressure gauges and valves with a couple of flow control orifices, and make the machine easier to use.

I think you're right about CDL, they put a whopper big pump in the RO tower to drive the recirc flow. There's another one that uses the last few stages of the HP Boost pump to drive the recirc. You can usually glean info from their Patents, just do a google search and shazzam --- full disclosure !


Ken, I didn't realize your place was so flat. I'm at the bottom of Sutton mountain. No flat land for miles around me.

T

[Teuchtar]

Here's some better quality photos.

http://www.flickr.com/photos/duncan_kathy/

[Teuchtar]

Dan:
Those are the 4040 Stainless pressure vessels from Atlantic.
http://formembranes.com/PV.pdf

[Sugarmaker]

Teuchtar,
Wow, nice job on the homemade R.O.! You have done a lot of research.
More taps in the future?

Regards,
Chris

[twobears1224]

TEUCHTAR:thanks for the writeup..i,am new to ro,s and it helped alot.one question.i noticed some small copper lines on your ro..what are those for?? pressure guages??

delbert