Hach SIGMA 900, User Manual

Page: 53 / 94

Section 5
Page 53
8837prg.fm
Flow Proportional Operation
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 .
2. Calculate t .
3. Multiply Q x t x 10 .
Therefore, the value entered for
INTV = _ _ _ _ CNTS
is 175.
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 .
2. Calculate t .
3. Multiply Q x t x 10 .
Therefore, the value entered for
INTV = _ _ _ _ CNTS
is 39.
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 .
Q
Average Flow Rate
Maximum Flow Rate
------------------------------------------------------
1.75 mgd
3 mgd
------------------------- 0.583 mgd = = =
t
a
n
---
1440 min
48 samples
------------------------------ 30 min/sample = = =
0.583 mgd 30 min/sample
×
10
×
174.9 =
Q
Average Flow Rate
Maximum Flow Rate
------------------------------------------------------
0.52 mgd
2.0 mgd
-------------------------
0.26 mgd
= = =
t
a
n
---
1440 min
96 samples
-------------------------------
15 min/sample
= = =
0.26 mgd 15 min/sample
×
10
×
39
=
Q
Average Flow Rate
Maximum Flow Rate
------------------------------------------------------
70 gpm
210 gpm
----------------------- 0.33 gpm = = =
t
a
n
---
480 min
32 samples
------------------------------- 15 min/sample = = =