ASTM D4189-95

Standard Test Method for Silt Density Index (SDI) of Water

SCOPE
1.1 This test method covers the determination of the silt density index (SDI) of water. This test method can be used to indicate the quantity of particulate matter in water and is applicable to relatively low (∧lt;1.0 NTU) turbidity waters such as well water, filtered water, or clarified effluent samples. Since the size, shape, and nature of particulate matter in water may vary, this test method is not an absolute measurement of the quantity of particulate matter.  
1.2 This test method is not applicable for reagent grade water Types I, II, and III of Specification D1193, or effluents from most reverse osmosis and ultrafiltration systems.  
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use .

General Information

• Status: Historical
• Publication Date: 31-Dec-1994
• Technical Committee: D19 - Water
• Drafting Committee: D19.08 - Membranes and Ion Exchange Materials

Relations

• Replaced By: ASTM D4189-95(2002) - Standard Test Method for Silt Density Index (SDI) of Water
• Effective Date: 15-May-1995

Standards Content (Sample)

Designation: D 4189 – 95
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Test Method for
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Silt Density Index (SDI) of Water
This standard is issued under the fixed designation D 4189; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 5. Significance and Use
1.1 This test method covers the determination of the silt 5.1 The SDI can serve as a useful indication of the quantity
density index (SDI) of water. This test method can be used to of particulate matter in water.
indicate the quantity of particulate matter in water and is 5.2 The SDI can be used to determine effectiveness of
applicable to relatively low (<1.0 NTU) turbidity waters such various processes such as filtration or clarification used to
as well water, filtered water, or clarified effluent samples. Since remove particulate matter.
the size, shape, and nature of particulate matter in water may 5.3 The SDI has been empirically correlated with the
vary, this test method is not an absolute measurement of the fouling tendency of some water treatment equipment such as
quantity of particulate matter. reverse osmosis devices.
1.2 This test method is not applicable for reagent grade 5.4 The SDI may vary as a function of water temperature,
water Types I, II, and III of Specification D 1193, or effluents and values obtained at different temperatures may not neces-
from most reverse osmosis and ultrafiltration systems. sarily be comparable.
1.3 This standard does not purport to address all of the 5.5 The SDI will vary with the membrane filter manufac-
safety concerns, if any, associated with its use. It is the turer. Thus, SDI values obtained with filters from different
responsibility of the user of this standard to establish appro- membrane manufacturers cannot be comparable.
priate safety and health practices and determine the applica-
6. Apparatus
bility of regulatory limitations prior to use.
6.1 SDI Assembly, as schematically described in Fig. 1. All
2. Referenced Documents wetted parts should be made of high-quality stainless steel or
plastic to prevent contamination by corrosion products. Do not
2.1 ASTM Standards:
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use reactive materials such as carbon steel or cast iron. Suitable
D 1129 Terminology Relating to Water
2
filter holders, designed to withstand an operating gage pressure
D 1193 Specification for Reagent Water
of 350 kPa (50 psi) can be obtained from suppliers of
D 3370 Practices for Sampling Water from Closed Con-
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membrane filters.
duits
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6.2 Membrane Filter, 47 mm in diameter, gridded, and with
E 1 Specification for ASTM Thermometers
a mean pore size in the range 0.45 6 0.02 μm, inclusive. Use
only filters that are packaged in the same orientation.
3. Terminology
6.3 Graduated Cylinder, 500-mL capacity.
3.1 Definitions—For definitions of terms used in this test
6.4 Stopwatch, graduated in hundredths of a minute.
method, refer to Terminology D 1129.
6.5 Thermometer, liquid-in-glass, suitable for measuring the
3.2 Definitions of Terms Specific to This Standard:
temperature of the water sample; capable of being read to
3.2.1 silt density index (SDI)—an index calculated from the
within6 1°C and conforming to the requirements as prescribed
rate of plugging of a 0.45-μm membrane filter.
in Specification E 1.
4. Summary of Test Method
7. Procedure
4.1 Water is passed through a 0.45-μm membrane filter at a
7.1 Assemble the apparatus as shown in Fig. 1 and set the
constant applied gage pressure of 207 kPa (30 psi), and the rate
pressure regulator at 207 kPa (30 psi).
of plugging of the filter is measured.
7.2 Before installing the membrane filter, flush the water to
4.2 The SDI is calculated from the rate of plugging.
be tested through the apparatus to remove entrained contami-
nants. For sampling, follow the procedure given in Practices
1 D 3370. Discrete samples can be used with appropriate pres-
This test method is under the jurisdiction of ASTM Committee D-19 on Water
and is the direct responsibility of Subcommittee D19.08 on Membranes and Ion surizing apparatus such as a booster pump to obtain a feed
Exchange Materials.
supply gage pressure of >276 kPa (>40 psi).
Current edition approved May 15, 1995. Published July 1995. Originally
7.3 Measure the temperature of the water.
published as D 4189 – 82. Last previous edition D 4189 – 94.
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7.4 Open the membrane filter holder and place a 0.45-μm
Annual Book of ASTM Standards, Vol 11.01.
3
Annual Book of ASTM Standards, Vol 14.03. membrane filter (47 mm in diameter) on the support plate of
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D 4189
7.9 After completion of the test, the membrane filter may be
retained for future reference.
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