Hach-Lange Sigma SD900 Portable - Manual (Page 56)

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Advanced sampling
5.3.5 Collect first flush stormwater samples
The stormwater option collects first flush (FF) samples or initial
runoff during storm conditions when pollutants are typically at a
high concentration. The first flush samples are collected at timed
intervals and can be initiated by an external device. A stormwater
program can run at the same time as the main program. The
stormwater option has the following capabilities:
• Collection of grab samples at up to 24 different time intervals.
First flush and main program flow-weighted composite samples
are automatically segregated. The first flush sample volume
may be set independently of the sample volume for the
flow-weighted composite.
• Initiation by an external device. A dry contact closure across
pins B and D on the auxiliary connector, held closed for at least
61 seconds, is required.
• When sampling with multiple bottles, the sampler can be
programmed to collect one large “first flush” sample (or small
multiple samples) at timed interval(s). The number of bottles
segregated for the first flush sample is selectable. Concurrently,
flow-weighted samples are collected from the beginning of the
storm until all remaining bottle(s) are filled, or after a user
selected time has elapsed.
Procedure:
1. Select PROGRAM SETUP > MODIFY SELECTED > ADV SAMPLING
from the main menu.
2. Select STORMWATER > ENABLE .
3. Select whether the program will be started immediately or from
an external device:
• Immediate—program starts when RUN is pressed and
START is selected.
• External—program starts when signaled by an
external device.
4. If configured for a single bottle, enter the number of first flush
(FF) samples to collect.
5. If configured for multiple bottles, enter the number of bottles to
be used for first flush collection.
6. Enter the multi-bottle distribution mode ( Figure 20 on page 38 ):
• Samples per bottle: more than one sample is collected in
each bottle
• Bottles per sample: more than one bottle is used to collect
each sample.
7. Enter the number of samples per bottle or bottles per sample.
8. Enter the time interval between each first flush sample cycle.
Variable intervals may be entered, or the same time may be
entered for each interval. The sum of the intervals is equal to