Hach 900 manual Section

Section 4

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.
	Q = --Average------------------------Flow---------------Rate-------------	= 3.5----------mgd----------- = 0.35 mgd
	Maximum Flow Rate	10 mgd
2.	Calculate t.

a 1440 min

t = --= ------------------------------ = 60 min/sample

n24 samples

3.Multiply Q x t.

0.35mgd ⋅ 60 min/sample = 21

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.
	Q = --Average------------------------Flow---------------Rate-------------	= 1.75--------------mgd----------= 0.583 mgd
	Maximum Flow Rate	3 mgd
2.	Calculate t.

a 1440 min

t = --= ------------------------------ = 30 min/sample

n48 samples

3.Multiply Q x t.

0.583 mgd ⋅ 30 min/sample = 17.5

Therefore, the value entered for INTV = _ _ _ _ CNTS is 18.

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.

Q = --Average------------------------Flow---------------Rate-------------	= 0.52--------------mgd----------= 0.26 mgd
Maximum Flow Rate	2.0 mgd
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Flow Proportional Operation	8544operations.fm