Switching concentrating to rinsing

[Brent]

I was wondering how much sugar is in the membranes when we start the cycle from concentrate to rinse, so I started measuring the concentrate. There was a gradual decrease from about 8% to 2.9% and it took a full 15 minutes to get there. So at a flow of about 0.8 GPM we losing 4 gallons of say an average of 4.5% if you do a straight switch over and dump the concentrate. So for the last few days when I changed modes, I waited for the concentrate to go down to under 3%, sometimes closer to 2% before I set it to dump the concentate.
While its doing this I leave the pressure and flows the same as while concentrating. As the sugar goes down the perm flow rate goes up from 2 to about 3.5 GPM
Anything wrong with this idea.

Also, it seems to me that the purpose of the exercise is to flush the hell out of the concentrate side of the membranes to clean them. If I set the pressure lever to full open and adjust the concentrate flow to about mid scale 3ish, then gradually increase the pressure about 75 lb. The concentrate flow indicator goes straight up to the top. Again if the purpose is to clean the concentrate side, the better flow the better, so I leave it at 75 psi and open the flow wide open.

I'm new to this machine but this all seems logical.

The lousy manual that came with it does not even tell you which pumps to run when rinsing of washing. If you followed what they say, you wouldn't even turn on either pump. Through trial and error I found that if the high pressure pump is not on the temperature will never rise to 120 degrees.

Comments from experience would be appreciated.

[royalmaple]

I don't know what your RO is like but you should have a "bypass" valve and that should be open when you are washing as well as your concentrate valve and your high pressure valve. Everything wide open.

When you open the bypass you don't get the flow through the flow meter but it is still happening, you just aren't seeing it.

Your not suppose to wash under pressure.

[Brent]

Matt there is nothing on this Airablo that "they" call a bypass valve

What is it supposed to be bi-passing to and from. Maybe I can figure it out.

If I just run everything wide open the pressure on the concentrate is about 55 - 60 anyway. So I'm not increasing much at all but that bit sure increases the flow on the dirty - concentrate side,

[danno]

I can't speak to the rinse/wash cycle, cause I'm just learning that myself.

But one of the first things the old owner told me - when you have no more sap, push some permeate through the system to push the left over concentrate from your RO into your head tank until your concentrate levels drop.

With 4 4" membranes, I push about 15 gallons of concentrate before I start a wash/rinse cycle. If you RO 15-20 times a season, that's a few hundred gallons of concentrate.

[royalmaple]

Brent-

The bypass valve is a two way valve and a second route that concentrate can take on its path through the machine. So when concentrating you have it closed and all the concentrate flow has to go through the flowmeter and out of the machine.

If you open up the valve you allow the concentrate to exit both through the flow meter but also directly out the machine through this bypass route.

I guess the theory is to have totally unrestriced flow out of the concentrate side of the machine when washing but allow you to build some pressure when concentrating.

Hope this helps.

[Russell Lampron]

Brent,

If I leave my by pass valve in wash mode and try to concentrate it will peg the concentrate flow meter. If you have one that does that it is your by pass valve.

Always flush the concentrate out of your membranes when you are done concentrating. The amount of sugar that you are pumping on the ground will make alot of syrup in the course of a season. I taste mine and check it with a refractometer to make sure it is flushed before I change over to wash mode. The extra permeate in the feed tank doesn't make much difference to your concentrate percentage.

[Brent]

Russ I think we are talking about the same valve. My manual calls it "V1" concentrate pressure regulaing valve"

A bit at a time over this season this rig has been passing more and more sugar. Today, last run, it's reading 1 to 1.1%

I still have a lot to learn about these machines but it seems to me that once they start to pass sugar, it's new membrane time. One the other hand, reductions in ratio of permeate flow to concentrate flow, indicate a cleaning problem.

Two things I've done that I now question,
A few nights ago I put it into wash mode (alk solution) and let it run up to temp and shut off automatically while I got some sleep. That left the hot alk ( aka soap ) in the membranes for about 8 hours.

The other thing I've been doing is increasing the pressure a little bit on the rinse cycle. The feed pump puts about 55 psi on the concentrate guage. Tweeking the "bi-pass" valve just a bit and increasing that to 75 psi puts a much large amount of flow over the concentrate side of the membrane, and my thinking is that this would make a better rinse.

Could either of these actions have led to me screwing up the membranes ??

[sapman]

Actually, Brent, I think the bypass would be the stainless valve (V19 maybe, on my Airablo anyway) around on the left side of the machine. When closed, the machine whistles pretty good, open it's a lot quieter, and pressures fall way off. V1 is more like a needle valve, I'd say, gradually increasing or decreasing pressure.

[driske]

Brent,
Off the top of my head, a 120F wash temp seems real high. Got a spec. sheet on NF270 and Mark One's up @ the sugar house. I'll reread that info and update this post tomorrow. Never washed my Full Flow at over a 100F though and the membranes are still tight after many years.
Passing 1% sugar makes for bad numbers in the barrel at nights end.

[Russell Lampron]

Brent the valve that I am talking about doesn't regulate anything. It only changes the path of the wash solution through the machine. On my machine it is valve #3. Like on Tim's machine my valve #1 is the high pressure control valve.

[driske]

Brent,
A friend downloaded spec sheets for NF-270 and NF-90 from applied membranes website. In the very fine print is a statement"Maximum temperature for continuous operation above pH10 is 95F"(35C)."
What happens if this is exceeded?? Does a 30 minute wash cycle constitute the definition of "continuous operation"?? I don't know.
Cripes and a crotch rocket. The more I learn about R.O. tech, the less I know.
Seems to be alot of info undisclosed by the folks selling us this gear.:o :confused:

[Brent]

Yeh 120 is the automatic cut out temp. The book says 115 and then says to let it run at least to 115 and it came wired to cut out at 120. In another section is says to wash to 118 degrees. I'm going to open up the control box and see how 120 was set and see if I can reduce it.
All the mixtures for preparing the soap, acid and glycering solutions refer to rigs with 8" membranes. Nowhere do the recommend PH values.
Needless to say the book is all but useless. I contacted the factory for a new one, no response.

The membranes are Hydanautic PVD1 and have 6 seasons on them.

I'm going to get new membranes for next year. The last run I did this season it was passing a lot of sugars 0.3 to 0.6% The new tech membranes sound like they will run a lot more permeate through at lower pressure.

============
I have one bi-pas valve on the intake from the feed pump, that selectes the raw sap / permeate from an outside source, or to re-circulate from the wash tank. Up top there is a pair of bi-pass valves that direct the permeate and concentrate either out of the machine to tanks or back to the wash tank. In between is a ball valve that is use to regulate the pressure on the concentrate.

[Jonathan Temple]

Sorry I'm very new at this R.O. stuff and I'm trying to clean and store my RO untill next year , my sugar shack is un-heated so are there cleaners and antifreeze I can use ??? I have two DOW XLE 4040 mambraines and what is the procedure to take care of them untill next year????
Thanks in advavce for all your help Maple Trader is a Great thing!!

[brookledge]

If you are not going to have them professionally cleaned and get a report on the performance of it then just put it in your storage vessel with the SMBS preservative or the type your membrane needs and put it in a warm place in your house until next season.
keith