Hach Sigma 1600, Instrument Manual

Page: 27 / 50

Section 3
Page 27
6507programming.fm
Sampler Programming Options
1. Calculate Q , where Q is the average flow rate (during the sampling
program) divided by the maximum flow rate. (The maximum flow rate
corresponds to the 20 mA output of the flow meter.)
2. Calculate t , where t is defined as a/n ; n is the total number of samples
collected over a given period of time; and a represents time in minutes,
over which n samples are collected.
3. Multiply Q x t . Enter the result in the programming step:
INTV = _ _ _ _ CNTS
.
Note: The product of Q x t is not necessarily a whole number. You must round off the
result to the nearest whole number.
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 .
2. Calculate t .
3. Multiply Q x t .
Therefore, the value entered for
INTV = _ _ _ _ CNTS
is 21.
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 .
Therefore, the value entered for
INTV = _ _ _ _ CNTS
is 18.
Q
Average Flow Rate
Maximum Flow Rate
------------------------------------------------------
3.5 mgd
10 mgd
--------------------- 0.35 mgd = = =
t
a
n
---
1440 min
24 samples
------------------------------ 60 min/sample = = =
0.35 mgd 60 min/sample
×
21
=
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
×
17.49
=