Pressure Keeps Climbing

[SeanD]

Yesterday was my first time RO-ing sap with my Deer Run 125. The only trouble I had was the pressure wouldn't hold steady and kept wanting to climb. If I let it go, the high pressure shut off kicked in each time. I had to back it off every five minutes or so.

It was mostly a lot of fiddling around opening and closing the valves on my part. I didn't really have a plan for rates. I just tried to keep the pressure somewhere between 250-275 psi.

Should I leave the recirc. valve closed for a certain amount of time at start up? Should I leave it alone entirely? I'd appreciate any strategies others are using.

Thanks,
Sean

[Mark-NH]

Hi Sean,

I have a 250 Ray RO. I start mine at 200 PSI and let it climb from there. It will climb and I may have too reduce pressure several times until it levels out. For me, I have not chased PSI level to be maxed out. At 200 + I am taking sap from 2% to between 6-7%. That is not maxing maching or filters and removing an amazing amount of water.

[SeanD]

Thanks for the input. That's good to know. I've had better luck the last couple of times aiming for 255 PSI. It seems when I aim for anything higher, it spikes more easily and kicks off.

Are you using the recirculation valve? I'm getting 6.5%, but only if I open the recirc valve 1.5 to 1.75 turns.

[maple flats]

I have a Ray Gingerich 250. I run mine at 270-275 and if running sap I open the re-circulation valve. In fact, once running I mostly use that valve to adjust the pressure. I've never had it climb that fast except on first start up, once it settles in I check and adjust if needed every fueling of the fire or 2 (9-18 minutes). Once running it generally does not need to be adjusted more than every 30-45 minutes or more, but I check anyway.
When I run a second pass, I leave the re-circulate valve closed and I start at about 200 PSI. After just a few minutes it climbs as the concentrate gets in the membranes and I turn it down to about 225. Then I check every time I add wood and once it settles in I set it to about 250-260. Second pass seems to need closer attention to the pressure. If it gets too slow on second pass, I have mine plumbed so I simply open the sap valve as I close the re-concentrate valve and then the pressure falls as the membrane gets cleaned somewhat by the new sap and I adjust the pressure back up to 270-275. Then for 2-3 times adding wood I again turn the pressure back up until it stabilizes more and then I return to the longer times between adjustments.