Additional filter pack (SDI-045) for use with the Silt Density Index Kit SDI-2000. Comes as a pack of 100 Filter Paper

Silt Density Index Meter Filter Paper


In stock (can be backordered)



Silt Density Index Meter Filter Paper is a specialized filter paper that is used in the SDI test. The filter paper is designed to remove all particles larger than 0.45 microns from the water sample. The water sample is then forced through the filter paper at a constant pressure, and the rate at which the water flows through the filter paper is measured. The resulting value is expressed in SDI units and is used to determine the quality of the water.

Overview : Silt Density Index Filters

  • SDI filters to perform Silt Density Index Testing for water
  • Package of 100 Filters – Good for 100 SDI Tests
  • Compatible with Applied Membranes SDI-2000 and SIMPLE SDI Test Kits
  • Applied Membranes SDI-045
  • 47mm 0.45M MF white disc hydrophilic membrane filters

What is the silt density index?

Silt is composed by suspended particulates of all types that accumulate on the membrane surface. Sources of silt are organic colloids, iron corrosion products, precipitated iron hydroxide, algae, and fine particulates. Silt Density Index testing is a widely accepted method for estimating the rate at which colloidal and particle fouling will occur in water purification systems, especially using reverse osmosis (RO) or Nanofiltration membranes.

SDI is a measurement of the fouling potential of suspended solids. It’s not measuring the quantity of particular matter, since the size and shape  can vary. Turbidity is a measurement of the amount of suspended solids. They are not the same and there is no direct correlation between them. In practical terms however, the membranes show very little fouling when the feed water has a turbidity of < 1 NTU. Correspondingly the membranes show very low fouling at a feed SDI of less than 5.

The SDI test is used to predict and then prevent the particulate fouling on the membrane surface. Other names for it are the Kolloid-Index (KI) or the Fouling-Index (FI). The test is defined in ASTM Standard D4189, the American Standard for Testing Material.

It measures the time required to filter a fixed volume of water through a standard 0.45µm pore size microfiltration membrane with a constant given pressure of 30 psi (2,07 bar). The difference between the initial time and the time of a second measurement after normally 15 minutes (after silt-built up) represents the SDI value.

The Silt Density Index (SDI) is a test that is commonly used in the water treatment industry to measure the quality of water. The test measures the ability of water to flow through a filter paper and is expressed in SDI units. Silt Density Index Meter Filter Paper is a key component of the SDI test, and in this article, we will provide an overview of how it works and outline the many benefits of using it.

Benefits of Using Silt Density Index Meter Filter Paper

  1. Accurate Results: This filter paper is designed to remove all particles larger than 0.45 microns, ensuring that the results of the SDI test are accurate and reliable.
  2. Consistency: The filter paper is manufactured to a high standard, ensuring that each batch of filter paper provides consistent results. This is important when conducting the SDI test, as consistent results are essential for accurate water quality measurements.
  3. Easy to Use: It is easy to use, with clear instructions provided with each pack. This makes it an ideal choice for operators who are new to the SDI test.
  4. Cost-Effective: This filter paper is a cost-effective way to conduct the SDI test. The filter paper is available in a range of sizes and quantities, making it easy to purchase the exact amount required for each test.
  5. Widely Used: It is a widely used and trusted product in the water treatment industry. It is used by water treatment plants, laboratories, and other organizations to ensure that water quality is maintained at the highest possible standard.

In conclusion, Silt Density Index Meter Filter Paper is a reliable and cost-effective product that is essential for conducting the SDI test. Its accuracy, consistency, ease of use, and wide usage make it an ideal choice for anyone who needs to test water quality.

Additional information

Weight 1 kg
Dimensions 20 x 30 x 15