Talk:Silt density index

Seawater
This article is insufficient; it is very important to give a more complete discussion of the typical SDI values around the world. MANY Reverse Osmosis plants ("watermakers") suffer constant problems because vendors/fabricators fail to take into account the true SDI value for the available seawater, with damages to the expensive Reverse Osmosis Permeators. — Preceding unsigned comment added by 192.100.181.87 (talk) 00:47, 7 April 2009


 * Much of the text was a copyright violation. I've rewritten the article and added some souced info about high SDI values for seawater in the Arabian Gulf.  I had difficulty tracking down a free-to-access papers, and the ones I did read dealt with a specific location.  However, all the ones I did read, talked of the high SDI of seawater or the almost acceptable SDI of "pretreated seawater" without saying what pretreatment was carried out.  Even so, I am unsure whether a "...complete discussion of the typical SDI values around the world" is necessary, or whether such info is freely available.  Astronaut (talk) 14:56, 9 April 2009 (UTC)


 * Manufacturers or vendors are not sufficient reference sources, although in some cases they may be appropriate as external links. See WP:SOURCE. ASTM is an acceptable "third party" type of organization. Citing ASTM publications is fine, as long as they are not plagiarized and are accurately cited (e.g. full title of document, date, page no., etc.). It is preferable, of course, to cite documents which are online and available to the public at no cost. Moreau1 (talk) 18:30, 9 April 2009 (UTC)

SDI is a common test used in the water industry. However it's not limited to SDI15 used for filtered water (typically after dual media filter or micro/ultra filtration). The calculation has to be explained to get a good understanding of the limitation of this test and the significance of the result.

SDI (T) = 100 * (1 - (t0/t1))/T

t0= initial time to filter 500mL through the 0.45um membrane at 30psi

t1= time to filter 500mL through the 0.45um membrane at 30psi after T minutes

for T=3, the typical range of value for the sea water is 15-25. theoritical maximum result is 33.333, anything above 32 would be irrelevant.

for T=15, the typical range of value for the filtered sea water is 0-5. Anything above 5 is meaningless as the maximum value is 6.666666 by calculation. It is commonly agreed to overlook result above 5. — Preceding unsigned comment added by Pavard.jp (talk • contribs) 00:18, 9 December 2011 (UTC)