Hach Sigma 900 User Manual page 53

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Example 2
You want to collect 48 samples over a 24-hour period on a 4–20 mA flow
proportional basis.
Average Flow Rate = 1.75 mgd (average flow rate over the 24-hour period)
Maximum Flow Rate = 3 mgd
a = 1440 minutes
1. Calculate Q.
Average Flow Rate
Q = ----------------------------------------------------- -
Maximum Flow Rate
2. Calculate t.
a 1440 min
t = -- - = ----------------------------- - =
n 48 samples
3. Multiply Q x t x 10.
×
0.583 mgd 30 min/sample
Therefore, the value entered for
Example 3
You want to collect 96 samples over a 24-hour period on a 4–20 mA flow
proportional basis.
Average Flow Rate = 0.52 mgd (average flow rate over the 24-hour period)
Maximum Flow Rate = 2 mgd
a = 1440 minutes
1. Calculate Q.
Average Flow Rate
Q = ----------------------------------------------------- -
Maximum Flow Rate
2. Calculate t.
a 1440 min
t = -- - = ------------------------------ - =
n 96 samples
3. Multiply Q x t x 10.
×
0.26 mgd 15 min/sample
Therefore, the value entered for
Example 4
You want to collect 32 samples over an 8-hour period.
Average Flow Rate = 70 gpm (average flow rate over the 8-hour period)
Maximum Flow Rate = 210 gpm
a = 480 minutes
1. Calculate Q.
Average Flow Rate
Q
= ----------------------------------------------------- -
Maximum Flow Rate
2. Calculate t.
a 480 min
t = -- - = ------------------------------ - =
n 32 samples
1.75 mgd
= ------------------------ - = 0.583 mgd
3 mgd
30 min/sample
×
10 = 174.9
INTV = _ _ _ _ CNTS
0.52 mgd
= ------------------------ - = 0.26 mgd
2.0 mgd
15 min/sample
×
10 = 39
INTV = _ _ _ _ CNTS
70 gpm
0.33 gpm
= ---------------------- - =
210 gpm
15 min/sample
Flow Proportional Operation
Section 5
is 175.
is 39.
Page 53