Hach SIGMA 900 - Manual (Page 31)

Section 4
Page 31
8544operations.fm Flow Proportional Operation
2. Calculate t.
3. Multiply Q x t.
Therefore, the value entered for INTV = _ _ _ _ CNTS is 4.
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.
2. Calculate t.
3. Multiply Q x t.
Therefore, the value entered for INTV = _ _ _ _ CNTS is 5.
Example 5
It is desired to collect 30 samples over a 2-day period.
Average Flow Rate = 0.25 cfs (average flow rate over the 48-hour period)
Maximum Flow Rate = 1 cfs
a = 2,880 minutes
1. Calculate Q.
2. Calculate t.
3. Multiply Q x t.
Therefore, the value entered for INTV = _ _ _ _ CNTS is 24.
You will notice from the previous five examples that the average and
maximum flow rate can be expressed in any units, i.e. mgd, gpm, cfs, etc.
However, express the average and maximum flow rate in the same units for
any given situation.
t
a
n
---
1440 min
96 samples
------------------------------- 15 min/sample = = =
0.26 mgd 15 min/sample
×
3.9 =
Q
Average Flow Rate
Maximum Flow Rate
------------------------------------------------------
70 gpm
210 gpm
----------------------- 0.33 gpm = = =
t
a
n
---
480 min
32 samples
------------------------------- 15 min/sample = = =
0.33 mgd 15 min/sample
×
4.9 =
Q
Average Flow Rate
Maximum Flow Rate
------------------------------------------------------
0.25 cfs
1 cfs
--------------------- 0.25 cfs = = =
t
a
n
---
2,880 min
30 samples
------------------------------- 96 min/sample = = =
0.25 cfs 96 min/sample
Ч
24 =