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Silt Density Index
Procedure
1) Before beginning the test, open
valves to allow flow through the SDI device to set the pressure
regulator for 30 psi.
2) Use tweezers to place a 0.45 micron filter in
the holder, top side toward the incoming water, and wet it
completely by slightly opening the vent valve on top as the
filter holder vent valve is opened. Close the vent valve.
3) Completely open the inlet valve and
immediately re-adjust the pressure regulator for 30 psi. Measure
the time in seconds required to fill the 500 mL graduated
cylinder (to).
[Empty the cylinder.]
4) Allow water to continue flowing for a
combined time of 5 minutes while maintaining the pressure at 30
psi. Again the measure the time required to fill the 500 mL
cylinder.
5) If possible, allow the water to flow for a
total time of 10 minutes and repeat the cylinder measurement.
6) If possible, allow the water to flow for
another 5 minutes and repeat the measurement. If any measurement
(in steps #5 or #6) is more than twice the initial measurement,
then it is invalid and the prior flow measurement (step #4 or
#5) should be used in the Silt Density Index calculation that
follows:
where:
t0 is the initial time
required for 500 mL of water to permeate the filter
tT is the time for the
500 mL of water to permeate after T minutes. T is the time in
minutes between the t0 and tT measurements, usually 5,
10, or 15 minutes
Download SDI procedures as a pdf file:
CEA_SDI_Procedures |
