GE P&W AutoSDI User Manual

AutoSDI

Automated Silt Density Index Tester

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
AutoSDI from GE’s Water & Process Technologies!

AutoSDI 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.

Fact Sheet

Fouling membranes and compromising water qual­ity can be expensive. With the simple AutoSDI 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 AutoSDI kit or Silt Density Index Testing System,
as shown in Figure 1, 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
collodial 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.

Figure 1: AutoSDI

The AutoSDI 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.

How is SDI Calculated?

The AutoSDI calculates SDI based upon the decay in
flow rate during a 15-minute period across a new

0.45-micron filter installed in the built-in holding
fixture. Flow rate measurement accuracy is ensured

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FS1061EN.doc Feb-11

by automatically maintaining a constant 30 psi
(2.07 bar) in the feed stream to the filter.

Flow rates are measured during the collection of
500 mL samples at the start of the test and after 5,
10, and 15 minutes. SDI units (percent decay per
minute) represent the degree of plugging that may
occur due to the feedwater stream particulate and
colloidal levels. The 15-minute SDI (SDI 15) is defined
by ASTM D 4189-95 as the interval required for ac­curate and standardized testing. The 5- and 10­minute SDI values are only estimates of the 15­minute value.

In addition to calculating SDI 15, the measured
decay in flow rate is also converted from an SDI
value to plugging factor (PF) value, a number
between 1 and 100%. 100 percent means the filter
is completely plugged. This provides an under­standable point of reference for the potential of
your RO membranes to plug—the higher the per­centage, the faster your membranes may become
fouled with particulates.

Table 1 details the product characteristics and or­dering information.

Table 1: Product Characteristics/Ordering Information

Product Characteristics

Range, SDI (15 minutes) 0-6.7 SDI units

Range, Plugging Factor 1-100% plugged

Electrical Power Selection 110-120V 60Hz or

Water Supply ¼-inch OD tubing via

Water Pressure – psi (bar) 65-100 (4.5-6.9)

HxWxD – inches (mm) 6x14x10 (15x36x26)

Weight – lb (kg) 8.0 (3.6)

Ordering Information

AutoSDI Tester Kit, 115V 1227464

AutoSDI Tester Kit, 220V 1227473

AutoSDI User’s Manual 1227468

SDI Membrane Filters, Box of 100 1215281

SDI Booster Pump Assembly,
120/240 VAC

220-230V 50Hz

quick-connect, 0.8 gpm
(3.0 Lpm) flow

3052333

Features

• In-Field flow calibration

• Built to ASTM D 4189-95

• No special tools or skills required

• Push-button operation

• Turn it on and walk away

• Lightweight and portable

• Rugged carrying case

• Audible alert with silence mode

• Repeatability within 0.2 SDI units

• LCD display

• Results remain on screen until reset

• Continuous flow readout in mL/min

• Global voltage compatibility

• Membrane replacement availability on-line

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

1. Connect Water

2. Insert Filter

3. Press Button

4. Read Results

For more information

• Email: [e-mail]

• Tel: [phone] USA

• Canada Tel: [phone]

• Web: www.geosmolabstore.com

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