RO Calculator?

[Aaron Stack]

I have permission to tap two neighboring properties to my borrowed trees with a few hundred tap potential each and trying to map out the next move or three.

Here’s a math problem I can’t figure out for now.

My stove is rated for “up to” 50 taps, and handles 33 just fine, running out a couple times a season. If I build an RO, what’s that like in a tap number I can try for? I want to get the hang of RO before spending real money, and want to grow gradually. I’ve had 50 without RO and that was tough to stay on top of. Broad question I know, but something like would 100 taps RO'd to say 5% be like running 75 taps?

[maple flats]

A very basic RO is typically able to remove about 50% of the excess water in 1 pass. Thus if you build an RO that does 5 gph flow, you would end up with 2.5 gph of concentrate. I have enough taps to get 50 gal of sap you will turn that into 25 gal concentrate. Then if you make the RO with the 5 gph flow in, ten hours later you have the 25 gal .
If you build a 10 gph RO you can do 2x as much sap.
The issue then is that you want to size the RO to your evaporator. Then start th RO first, and if the RO output equals the evaporation rate, about 1 hr later start boiling. The big thing to realize is that concentrate spoils faster, much faster, thus you don't want to get concentrate too far ahead.
For example, on my previous evaporator (a 3x8 wood fired) my evaporation was between 60-70 gph. My RO ran 250 gph input and that RO removed 75% of the excess water, thus the output was about 62-63 gph. I tried to fire the evaporator to match it. I started running the RO into my head tank, as soon as I had 20-25 gal in the head tank I lit the evaporator. On my feed line between my head tank and my preheater I had a 5/16" vinyl tube that teed off the feed line, went up and over the very top of the endwall (in my case 10' walls, then 6' more up the end wall less 5.5' height of the elevation of the feed line off the floor, so the tube ran up 10.5' high, then out side and back into the head tank. The reason for that much was because when I first filled the head tank and first opened the valve on the head tank I got a mix of concentrate and air, inrush in the sight tube and before I ran the tube up the 10.5' and back down I lost some concntrate. Routing the sight tube back to the head tank meant any concentrate that pushed up and out was not lost.
My ne evaporator will be near similar evaporation, likely 55-60 gph if I get it converted to oil, maybe 40-45 gph if it remains wood fired for 2025, but I'll just need to determin the evaporation. If I get to run a double pass I will, if the head tank gets to maybe 50 gal, I design the plumbing swo I only need to close one valve, open another valve and I'm pulling concentrate from the head tank and pushing it thru the RO a second pass. When I do that I need to turn the operation pressure back because my RO won't run 250 gph if the entering sugar is 8%, but you get the picture. Then as the head tank falls to about 10-15 gal, I turn the 2 valves back at run sap into the RO rather than concentrate. Then I turn the pressure back up. This took longer to explain than it takes to change from sap in to concentrate in and back again. I just need to keep my eye on everything and react as needed.
I however suggest you design an RO to handle 10 gph sap in and work from there. If you make an RO using a single 4" x 40" membrane you can very easily have a 50 or even a 100 gph sap gph inflow. Just use the right pump to get it.
An RO works simply by pushing sap under pressure thru the RO membrane, the higher the pressure the higher the % of concentrate you get out. If you can't justify a pump to get 50 gph flow in, get a smaller pump but a 4x40 membrane. You will sitll remove lots of water, then as your needs increase just take the smaller pump off and put a larger on. The pressure is generated by the pump pushing against a restricting valve, open the valve lower pressure, close it a little the pressure goes up.