Hach 900 manual You want to collect 32 samples over an 8-hour period

Section 4

2.Calculate t.

a 1440 min

t = --= ------------------------------= 15 min/sample

n96 samples

3.Multiply Q x t.

0.26mgd × 15 min/sample = 3.9

Therefore, the value entered for INTV = _ _ _ _ CNTS is 4.

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.
	Q = --Average------------------------Flow---------------Rate-------------	= --70--------gpm------------= 0.33 gpm
	Maximum Flow Rate	210 gpm
2.	Calculate t.

a 480 min

t = --= ------------------------------= 15 min/sample

n32 samples

3.Multiply Q x t.

0.33mgd × 15 min/sample = 4.9

Therefore, the value entered for INTV = _ _ _ _ CNTS is 5.

Example 5

It is desired to collect 30 samples over a 2-day period.

Average Flow Rate = 0.25 cfs (average flow rate over the 48-hour period) Maximum Flow Rate = 1 cfs

a = 2,880 minutes

1.	Calculate Q.
	Q = --Average------------------------Flow---------------Rate-------------	= 0.25--------------cfs------= 0.25 cfs
	Maximum Flow Rate	1 cfs
2.	Calculate t.

a 2,880 min

t = --= ------------------------------= 96 min/sample

n30 samples

3.Multiply Q x t.

0.25cfs × 96 min/sample = 24

Therefore, the value entered for INTV = _ _ _ _ CNTS is 24.

You will notice from the previous five examples that the average and maximum flow rate can be expressed in any units, i.e. mgd, gpm, cfs, etc. However, express the average and maximum flow rate in the same units for any given situation.

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8544operations.fm	Flow Proportional Operation