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Time Unit
seconds (cfs, m
minutes (gpm, l/m, etc.)
3
hours (gph, m
h, etc.)
3
days (mgd, m
d, etc.)
3. Divide the sample interval (I
The final value is the number of pulses you enter in this
screen.
The steps can be summarized in the equation below.
÷ (Q
÷ K
) = Number of pulses
I
samp
max
time
Note
The equation requires similar units for Q
the volume and flow rate units must use the same basic unit
(cubic feet and cubic feet per second, gallons and gallons per
minute, etc.). If they are dissimilar, convert the units before
applying them to the equation.
Example 1 – Consider a flow meter programmed to output 20 mA
at 1,000 liters per minute, the peak flow rate of the channel. If
you are required to collect a sample every 10,000 liters, you
would enter 50 flow pulses according the equation.
10000 liters ÷ (1000 liters per minute ÷ 5) = 50 pulses
Example 2 – Consider a flow meter programmed to output 20 mA
at 20 cubic feet per second. If you are required to collect a sample
every 2400 cubic feet, you would enter 10 flow pulses according
the equation.
2400 cubic feet ÷ (20 cubic feet per second ÷ 0.08333) = 10 pulses
Example 3 – Consider a flow meter programmed to output 20 mA
at 8 mgd (million gallons per day) and you are required to collect
a sample every 10,000 gallons. Because the base units are dis-
similar, you first must convert either the flow rate to gallons per
day or your sample interval to millions of gallons. (The example
below shows the flow rate converted to gallons per day.) After
completing the equation you would enter 9 flow pulses.
10000 gallons ÷ (8000000 gallons per day ÷ 7200) = 9 pulses
Isco 4700 Refrigerated Sampler
Section 3 Programming
F
Factor
time
3
s, etc.)
0.08333
5
300
7200
) by the result of step 2.
samp
and I
max
. That is,
samp
3-15
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