Hach 900 MAX Instrument Manual page 137

8990apdx_pulsecounts.fm
Use the following examples to help you determine the value that you need to
enter when programming for sampling based on counts.
Example 1
You want to collect 24 samples over a 24-hour period on a 4–20 mA flow
proportional basis.
Average Flow Rate = 3.5 mgd (average flow rate over the 24-hour period)
Maximum Flow Rate = 10 mgd
a = 1440 minutes
1. Calculate Q.
Average Flow Rate
Q = ----------------------------------------------------- -
Maximum Flow Rate
2. Calculate t.
a 1440 min
t = -- - = ----------------------------- - =
n 24 samples
3. Multiply Q x t x 10.
×
0.35 mgd 60 min/sample
Therefore, the value entered for
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
3.5 mgd
= -------------------- - = 0.35 mgd
10 mgd
60 min/sample
×
10 = 210
INTV = _ _ _ _ CNTS
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
How to Calculate Pulses/Counts
Appendix D
is 210.
is 175.
Page 135