Hach SIGMA 900 - Section 5 Programming - 4-20 mA Flow Signal Calculations (Part 2); 4-20 mA Signal to Pulse Conversion Calculations

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== =