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Old 26-12-2013, 09:58   #1
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Anyone installed generic membrane in SR Ultra Whisper 600 Modular watermaker?

Hello..

The factory supplied membrane for this unit is what Sea Recovery calls "C size", which I understand is 40" long by 3" diameter. Unfortunately there are no cheap "generic" membranes of this size (probably as arranged by SR with manufacturers!)

I am evaluating the possibility of replacing the membrane housing to enable the use of cheaper "generic" membranes. The question is what size of membrane?

40"x2.5" (as in Filmtec SW30-2540, rated at 700 gpd based on 800 psi and 8% recovery) would be a bit too small given that this unit has to run at lowish pressure because of the fixed 13% recovery implied in the ETD design.

I am wondering if the SW30-4021 (4" diameter x 21" length) membrane would work. It is rated at 800 gpd but this is based on 800 psi and 5% recovery. I am afraid I do not have the curves to get a gpd figure for 13% recover and 650 or so psi.

Does anyone have empirical or theoretical data as to whether the SW30-4021 would work fine in this unit?

Thanks in advance!

Charlie
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Old 26-12-2013, 11:08   #2
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Re: Anyone installed generic membrane in SR Ultra Whisper 600 Modular watermaker?

Hi Charlie

I have an HRO SEM-400 which is very similar to your Sea Recovery system. I replaced the HRO membrane housing with a standard 40x2.5 housing and the membrane with a Filmtec SW30-2540. It works fine.

The output of a watermaker with an ETD is determined by the gpm of the pump and the recovery rate built into the ETD. The size of the membrane will determine the resulting pressure. A larger membrane yields a lower pressure and a smaller membrane a higher pressure. The pressure went from 550psi to about 700psi when the membrane size was reduced from 3" to 2.5". If you went to a 4" membrane the pressure would drop below 500psi.

The flow rate per area of the membrane determines the TDS passed through. The low flow rate through the 4'' membrane would yield a TDS reading of 800. The TDS reading improved from about 500 to 300 with the change from a 3" to a 2.5" membrane.

The SW30-2540 is a perfect replacement for the custom 3" membrane. Pressure goes up, TDS goes down and production remains the same.

Chuck
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Old 26-12-2013, 11:35   #3
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Re: Anyone installed generic membrane in SR Ultra Whisper 600 Modular watermaker?

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Originally Posted by ChuckSK View Post
Hi Charlie


The SW30-2540 is a perfect replacement for the custom 3" membrane. Pressure goes up, TDS goes down and production remains the same.

Chuck
Chuck

Thank for your post. I am a bit concerned about the increase of presssure at the membrane because that drives a proportional increase of pressure into the ETD. Those ETDs are made out of plastic and they do not last long even before increasing the pressure.

Do you know what is the % increase in membrane pressure that would be required to compensate for the change from 3" to 2.5"?

I am afraid I do not have access to tehe surface area of the 2.5" membrane, which is one of the drivers of that difference. Hopefully someone will have that piece of data....

Charlie..
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Old 26-12-2013, 11:54   #4
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Re: Anyone installed generic membrane in SR Ultra Whisper 600 Modular watermaker?

The pressure went from 550 psi to 700 psi.
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Old 26-12-2013, 18:50   #5
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Re: Anyone installed generic membrane in SR Ultra Whisper 600 Modular watermaker?

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The pressure went from 550 psi to 700 psi.
Many thanks. That is very useful.

Charlie
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Old 27-12-2013, 10:47   #6
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Re: Anyone installed generic membrane in SR Ultra Whisper 600 Modular watermaker?

Hi Charlie

I managed to miss that your system is a 600 gpd, not a 400 gpd. That little fact nullifies my recommendation. The pressure with a single SW30-2540 would be 860 psi which is too high. I ran a series of calculations using Dow Chemical's ROSA program.

SW30-2540 860 psi 238 TDS
SW30-4040 560 psi 306 TDS
2 SW30-2540 in series 590 psi 426 TDS

These results were with inputs of 13% recovery and 25 GPH production.

The SW30-4040 study produced a low flow rate warning. The study with 2 SW30-2540 in series produced no warnings.

So, you have 2 choices, neither of which may be cheaper than the custom Sea Recovery membrane.

Chuck
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Old 27-12-2013, 11:45   #7
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Quote:
Originally Posted by ChuckSK View Post
Hi Charlie

I managed to miss that your system is a 600 gpd, not a 400 gpd. That little fact nullifies my recommendation. The pressure with a single SW30-2540 would be 860 psi which is too high. I ran a series of calculations using Dow Chemical's ROSA program.

SW30-2540 860 psi 238 TDS
SW30-4040 560 psi 306 TDS
2 SW30-2540 in series 590 psi 426 TDS

These results were with inputs of 13% recovery and 25 GPH production.

The SW30-4040 study produced a low flow rate warning. The study with 2 SW30-2540 in series produced no warnings.

So, you have 2 choices, neither of which may be cheaper than the custom Sea Recovery membrane.

Chuck
Chuck
Maaaany thanks! I was factoring up your 400GPD data but your "proper" analysis is much better. You have woken up the engineer in me and I will take some time to play with the Dow software.

On the bigger picture, hats off to the Sea Recovery for doing well their job of keeping customers "captive" with the combination of GPD ratings and ETD design that makes it difficult to "jump ship" at membrane replacement time... In a prior life marketing chemicals I used to work on that sort of thing and it is fun!

Back to watermakers, I take that an optimal long-term solution could entail changing GPD via rpm of the feed pump motor...... I am still awaiting prices of the 40x21 membrane....

Many thanks again
Charlie
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Old 27-12-2013, 13:03   #8
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Re: Anyone installed generic membrane in SR Ultra Whisper 600 Modular watermaker?

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I ran a series of calculations using Dow Chemical's ROSA program.

I would make a comment about using the DOW ROSA software for marine water maker (Batch) applications.

The ROSA software is designed for RO Membrane applications where the membrane is running 7 days a week, 365 Days a year. In these commercial applications maximizing membrane life is a key design criteria cost factor, much more important than the initial build cost. A marine RO Membrane application operating in a batch mode, you will have a hard time ever reaching the total operating hours found in a 365/7 days application. For a boat application, we care more about hourly fresh water production and power usage for the Hp pump. The RO Membrane is viewed as a long term consumable part.

Just to give you an example. Our 20 gallon per hour water maker using a 1.6GPM Hp pump and the SW30-2540 RO Membrane has close to a 23% recovery rate (TDS 150ppm). The DOW ROSA software would be flashing RED lights because you would never design a continuous operating RO System for a Municipality or chemical plate with a 23% recovery rate. The never ending O&M costs are what you focus on and that is where the 7% recovery rate number comes from, but it is somewhat meaningless for a marine batch process water maker. Lots of folks grab hold of the ROSA software without properly understanding its application or intent and it causes them to make bad membrane choices, giving up lots of fresh water production in the process.



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Old 27-12-2013, 13:21   #9
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Re: Anyone installed generic membrane in SR Ultra Whisper 600 Modular watermaker?

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Originally Posted by SV THIRD DAY View Post
I would make a comment about using the DOW ROSA software for marine water maker (Batch) applications.

The ROSA software is designed for RO Membrane applications where the membrane is running 7 days a week, 365 Days a year. In these commercial applications maximizing membrane life is a key design criteria cost factor, much more important than the initial build cost. A marine RO Membrane application operating in a batch mode, you will have a hard time ever reaching the total operating hours found in a 365/7 days application. For a boat application, we care more about hourly fresh water production and power usage for the Hp pump. The RO Membrane is viewed as a long term consumable part.

Just to give you an example. Our 20 gallon per hour water maker using a 1.6GPM Hp pump and the SW30-2540 RO Membrane has close to a 23% recovery rate (TDS 150ppm). The DOW ROSA software would be flashing RED lights because you would never design a continuous operating RO System for a Municipality or chemical plate with a 23% recovery rate. The never ending O&M costs are what you focus on and that is where the 7% recovery rate number comes from, but it is somewhat meaningless for a marine batch process water maker. Lots of folks grab hold of the ROSA software without properly understanding its application or intent and it causes them to make bad membrane choices, giving up lots of fresh water production in the process.


In this case the 13% recovery rate is fixed by the physical characteristics of the ETD and can not be changed. ROSA was being used to determine pressures for various alternatives and not for system design.

Chuck
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Old 27-12-2013, 18:47   #10
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Re: Anyone installed generic membrane in SR Ultra Whisper 600 Modular watermaker?

Hi Charlie

A little more information. The recent versions of ROSA do not include data for the SW30-4021. Version 6.1.5 (June 12,2007) does. Surprisingly, the SW30-4021 results in a pressure of 880 psi vs. 860 psi for the SW30-2540 even though the active area is greater, 33 sf vs 28 sf.

You can download it from the Dow Chemical ROSA site.

Chuck
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Old 27-12-2013, 19:01   #11
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Re: Anyone installed generic membrane in SR Ultra Whisper 600 Modular watermaker?

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In this case the 13% recovery rate is fixed by the physical characteristics of the ETD and can not be changed. ROSA was being used to determine pressures for various alternatives and not for system design.
Exactly Chuck, I just wanted to give the needed warning about the limitations of ROSA on conventional water makers operating with a simple back pressure generating devise. We sell water maker parts to cruisers building their own water makers weekly, and if they get ahold of the ROSA software from a chat room link without a proper understanding (especially if they are engineers or stayed at a Holiday Inn last night) they head down a path that will screw them out of valuable product water prodution.
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