Dear Yalakambedu,

Apply mass balance at the inlet and outlet of o your pipe.

By assuming diffusion to be negligible, you can get a rough estimate as

Time required will be = cross section area of the pipe*length*density of argon/mass flow rate of argon

Dear Yalakambedu, Syed is correct. There are a number of important factors which must be known to accurately estimate or produce a procedure for this purge. Argon is heavier than Nitrogen so this density difference can work for you or against you. If for example the pipe section is vertical and you can flow Ar in the bottom and vent out the top, and do it slowly so there is little turbulence, you can nearly achieve perfect displacement of the N2 with little loss of the more expensive Ar. If time is a factor then you may have to blow the Ar in and use a gas analyzer at the outlet to achieve a sufficiently high molar ratio of Ar to N2 to meet whatever your requirements are. Without knowing more it is difficult to make specific recommendations.

Thank you Syed and Stanley.

I wish to calculate theoretically, time required to flush out each gas from the pipe of 10 mm diameter and 10 m length. Please suggest any formula for calculating the same.

Actual scenario is, if pipe has already N2, if I want pass Ar in the same pipe with 6 bar pressure. Under this condition how much time would be required for the same.

Thanks in advance,

Bhargava

@ Syed

Please mention, unit of measurement to be considered for each of the parameter. It would be helpful if you can share any example calculation.