Rated gph for membranes?

[RO_Guy]

I'm trying to find the rated gph for NF270s and NF70s. I think I read somewhere that NF270s are 600 gph but I'm not certain. Might anybody know?

[Brent]

You should be able to get that from the DOW site.

That will be a warm water (77 Fdeg / 25 Cdeg) flow. Subtract 3% for each degree Centigrade you go below that. Final number for sap will be about 1/3 of the warm water rate.

[green4310]

Max flow on four inch is 16gpm/960gph.

[maple connection]

I think the NF270 8" membrane is rated at 550 to 600 GPH. Not sure on the NF70. Hope that helps.
My 4" membrane is rated at 80GPH. I just picked up the machine afew days ago So, I need to find out what membrane is in the machine. The owner was unsure.

[RO_Guy]

You should be able to get that from the DOW site.

That will be a warm water (77 deg) flow. Subtract 3% for each degree you go below that. Final number for sap will be about 1/3 of the warm water rate.The DOW website says the NF270-400 has a feed flow of 70 gpm. That's 4200 gph. And 1/3 of that for sap temperatures is roughly 1400 gph. Isn't that a long way from 600 gph? Am I missing something? :confused:


I think the NF270 8" membrane is rated at 550 to 600 GPH. Not sure on the NF70. Hope that helps.Do you have a source?

[Brent]

While digging into the tech papers on Dow's web site I found a document that said that the LP4040 was particularly well suited for running at colder temperatures. The XLE4040 was on the same spec sheet and did not have a comment about cold temperatue performance. So I asked Dow to clarify the situation and after several exchanges the following is what I got back from them.

============================
Mr. Roberts,

I received your request about getting more temperature specific information regarding performance differences with the XLE-4040 and LP-4040 elements. The general rule of thumb is that for every degree Celsius in temperature change from 25deg C (77F) one can expect a 3% change in flow due to the increased water viscosity. For the feed temperatures you have in mine that amounts to a 50-75% flow drop in the range you have. So 65% flow drop is not unreasonable.

Kind regards ,
Denise Haukkala
Dow Water & Process Solutions
Technical Service
1-703-765-0729 phone
DRHaukkala@dow.com
==================================

In another email they said the the XLE4040 was the highest flow available.

So I went ahead and gave Joe and order for the XLE4040 membranes. I may actually get to run them next week.

Hope this help clarify the somewhat muddy waters.

[Gary in NH]

The drop in flow rate will be for permeate flow only or the "water" side of the membrane. Add the flow of concentrate to the permeate flow to get the actual feed flow rate in GPM or GPH.