Hach SIGMA 900 - Section 5 Programming - Flow Proportional Sampling Calculations; Calculating Intervals Using External Pulses

Section 5
Page 51
8837prg.fm Flow Proportional Operation
2. Multiply the flow increment between samples, f, by the pulse frequency
output of the flow meter (i.e. 1 pulse per 100 gallons, 1 pulse per 1,000
gallons, etc.). If the pulse frequency output of the flow meter is not known,
consult the flow meter manufacturer.
Note: The final result is not necessarily a whole number. You must round off the result
to the nearest whole number.
Example 1
You want to collect 35 samples over a 24-hour period. The total expected flow
over this period is 235,000 gallons. The flow meter pulse frequency is
one pulse for every 100 gallons.
1. Determine the flow increment between samples:
2. Multiply the flow increment, f, by the pulse frequency output of the flow
meter.
Therefore, the value for
INTV = _ _ _ _ CNTS is 67.
(67.14 is rounded off to 67.)
Example 2
You want to collect 24 samples over an 8-hour period. The total expected flow
over this 8-hour period is 85,000 gallons. The flow meter pulse frequency
output is one pulse for every 50 gallons.
1. Determine the flow increment between samples:
2. Multiply the flow increment, f, by the pulse frequency output of the flow
meter.
Therefore, the value for
INTV = _ _ _ _ CNTS is 71.
Example 3
You want to collect 48 samples over a 16-hour period. The total expected flow
over this period is 1,750,000 gallons. The flow meter pulse frequency output
is one pulse for every 1,000 gallons.
1. Determine the flow increment between samples:
2. Multiply the flow increment, f, by the pulse frequency output of the flow
meter.
Therefore, the value for
INTV = _ _ _ _ CNTS is 36.
f
Q
n
----
235,000 gallons
35 samples
------------------------------------------ 6,714 gallons/sample== =
6,714 gallons/sample
1 pulse
100 gallons
------------------------------
× 67.14 pulse/sample=
f
Q
n
----
85,000 gallons
24 samples
-------------------------------------- - 3,542 gallons/sample== =
3,542 gallons/sample
1 pulse
50 gallons
---------------------------
× 70.84 pulse/sample=
f
Q
n
----
1,750,000 gallons
48 samples
----------------------------------------------- 36,458 gallons/sample== =
36,458 gallons/sample
1 pulse
1,000 gallons
-----------------------------------
× 36.458 pulses/sample=