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SDI Testing Made Easy

If you thought performing a silt density index (SDI) test to predict membrane fouling potential was too tedious, costly and time consuming, welcome to Auto SDI.

Auto SDI eliminates the need for stopwatches, graduated cylinders, calculators and tedious labor. In less than twenty minutes you will know 5, 10, and 15 minute SDI results as well as Plugging Factor.

Fouling membranes and compromising water quality can be expensive. With the simple Auto SDI kit and a water source of 65 psi (4.5 bar) and at least 0.8 gpm (3.0 Lpm), membrane particulate fouling can be avoided and system performance optimized.

The Auto SDI kit or Silt Density Index Testing System, as shown above, includes the tester, carrying case, 12 VDC Power Supply, pressure guage, inline prefilter, SDI membrane filters (box of 100), and a user's manual.

What is the Silt Density Index

Silt Density Index (SDI) testing quantifies the amount of particulate contamination in a water source. SDI is widely accepted for estimating the rate at which colloidal and particulate fouling will occur in water purification systems – especially in applications using reverse osmosis (RO) membranes. Water sources often change their water quality and this test often needs to be done weekly or monthly.

The Auto SDI tester automatically calculates a relative value for the amount of suspended matter in feedwater streams. Measured values reflect the rate at which a 0.45-micron membrane filter will plug with particulate material when feedwater is flowing through it. The ASTM chose the 0.45 micron filter because it is more likely to clog from colloidal matter than from hard particles such as sand or scale. SDI testing is commonly used as an “early alert” to ensure that particulates in feedwater do not plug the micropores in RO membranes.

The Fast, User-Friendly, and Accurate Way of Measuring Silt Density Index

1. Connect Water
2. Insert Filter
3. Press Button
4. Read Results

Product Characteristics

• Range, SDI (15 minutes): 0–6.7 SDI units
• Range, Plugging Factor: 1-100% plugged
• Electrical Power Selection: 110-120V 60Hz or 220-230V 50 Hz
• Water Supply: 1/4-inch OD tubing via quick-connect, 0.8 gpm (3.0 Lpm) flow
• Water Pressure - psi (bar): 65-100 (4.5-6.9)
• HxWxD - inches (mm): 6x14x10 (15x36x26)
• Weight - lb (kg): 8.0 (3.6)