SPIRAL MEMBRANES REVERSE OSMOSIS 2

[Shanzon]

Hi...

I am starting to work using R.O. Spiral membranes, I would like to understand when manufacturer provide information as 80 mil, 43 mil...what is exactly part of the membrane use to have this kind of measurement?
If I am intending to calculate filtration area have I to consider this number?
Please, feel free to comments and advise....

Thanks in advance,

Araujo

 

[aspearin1]

"mil" is generally a thickness measurement. 1 "mil" is 0.001 inches. Filtration area is not directly correlated to thickness, but you can take the (OD-ID)/thickness. This will give you the relative number of wraps of the membrane. If you assume equal spacing of these wraps, you can find the (quasi-)circumference of each one, and add them up. Multiply that by the length and you have your total area. There may be a more standard method. But this is one way I can see where a thickness measurement may come into play. Be sure, though, that the thickness measurements include the open layers of webbing sandwiched between the spirals.

ChemE, M.E. EIT
"The only constant in life is change." -Bruce Lee

 

[Shanzon]

aspearin1

Thank you...I am gonna try this way.....
Sorry, I have a question about spiral membranes..usually
this is the layer configuration....Membrane/Feed Spacer/Membrane and between this some kind of plastic mesh...I saw a scheme in website Osmonics..
When I am using a Membrane 43 mil versus 80 mil..is it correct to predict 80 mil will show better flow performance?
According to your helpful information, it is possible to have a 43 mil and 80 mil with the same filtration area. is this measurements regarding to feed spacer? is this can be parallel or diamond? am I on the right way..
As I told before, I am a begginer...feel free to advise..

Araujo

 

[cub3bead]

Araujo,

The thickness of the feed spacer, while important, is not the parameter of primary concern in designing an RO system. The thinner feed spacers allow the manufacturers to put more membrane area within the fixed 2.5, 4 or 8 inch standard cartridge diameters. Generally, the cartridges are 40" long though 1 manufacturer makes 60" long cartridges. This one also makes 17" dia X 60 long cartridges for very large systems.

The problem you encounter with thinner feed spacers is the feed must be very, very clean to minimize fouling of the feed spacer.

The more important parameter to look at is the membrane flux rate.

Hope this helps.

 

[Shanzon]

OK...so I was undertanding....thinking about a simple membrane sheet to prepare a spiral.

a) Membrane Sheet/Feed Spacer Sheet/Membrane Sheet using epoxi glue...ok? Feed spacer in spiral wound stays betwen two membrane sheets, this Feed Spacer can be paralell or diamond, corrugated..ok? I do not understand, what is nomenclature for that "plastic" screen among layers?
I am a little bit confuse about these details....

Maybe I am complicating simple things...in Perry book I saw as 1 stack...for example: 1 membrane sheet==corrugated feed spacer===1 membrane sheet...usually only 3 sheets?

b) As you told....if I am using the same cartridge size...and if I am intending to compare filtration area 43 x 80 mil..it is expected a difference.

 

[aspearin1]

If you have a cartridge of the same diameter (ID and OD) and the same thickness of the spacer, then the 80 mil membrane will result in a lower number of wraps than the 43 mil membrane. This will translate to a higher filtration area for the 43 mil membrane because there is more membrane put into the same alloted space. The above assumptions are critical, though. The spacer needs to be the same thickness, as does the ID and OD of the cartridges.

ChemE, M.E. EIT
"The only constant in life is change." -Bruce Lee

 

[Shanzon]

OK...I going to read some papers about R.O...to understand your conclusion...I do not be a troublemaker..haha
Only to be short...what is the sequence starck in a R.O. membrane...?

membrane...feed spacer....membrane??

In RO membranes there are, membrane; feed spacer; membrane; and mesh spacer?

Araujo

 

[fd74]

Well, a simple answer to your first question: if you are looking for filtration area just browse into a manufacturer's (Osmonics, Dow, Koch, ...)technical documentation, and you'll find that.

Maybe this is not what you mean...

Salute,

fd74