speed and flow in a sample pipe connected to main pipe

[hayya]

Hi
i need a solution of this question,
An instrument is installed along a major water distribution pipe line to detect potential contamination.A 2.54 cm dia. pipe connects the instrument to the water distribution pipe.The connecting pipe is 20 m long.water from distribution pipe is pumped through the instrument and then discharged to a holding tank for verification analysis.If the flow rate of water in the sample line is 1L/min.how many minutes will it take a sample from distribution pipe to reach the instrument.Use the following relationship to determine speed in sample pipe
u = Q/A
u = speed of water in pipe in m/sec
Q =flow rate in pipe in cubic meter/ sec
A= area of the pipe in square meter
If the instrument uses 10L/min for sample analysis, how many liters of water must pass through the sampler before it detects the contamination in the pipe. thanx alot

[admin]

For the stated flow rate of 1L/min and pipe diameter d=25,4 mm I get v=1.97 m/min.
This means that 20 m will require 20/1,97 = 10,15 min.
You can use calculator at:
http://www.pipeflowcalculations.com/flowrate/index.htm
for this calculation.

If flow rate is 10 L/m than the time is 10 times shorter - 1,015 min

When will instrument detect contamination depends on its sensitivity I think.