hello members
i have a tubing problem regarding purging.
i have a series of tubes over 4kms long and i need to weld bundles together. once this butt is done the distance will increase to 8kms
i need to purge from one end 4km from the position of the butt. the tubes are 1" and 1/2" dia.
can someone familiar with the required calculations supply me with the time it will take to run at 30l/min from the purge end pushing the old gas out to the butt and then a further 150 metres.

also can someone give me a figure of approx pressure being expelled at the butt and also at the end of the 150 m point.

bear in mind that this is across undulating country, not flat.

ambient temp is around 30c and the gas is nitrogen

thanks vry much

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