Gas Velocity in Branch

[ghamsa]

Hello

Please helpe to find out the right equation to solve the following problem:

There is a 16 in. line with 60 psig and 75 F gas (mathane) flowing in the line.
If I want to make a 3 in. branch from this 16 in. line, which disharges to the atmosphere how can I calculate the gas velocity in the 3 in. branch? ( Note: I do not know what the flowrate in the 16 in. is)

 

[MortenA]

the flowrate in the 16" is not very important - unless your new "consumer" will cause the pressure to go down as a consequence of increased overall flow in the main line.

If the pressure at the branch dosnt change then you can calculate it as a 3" line with dischage to atm. It will (most likely) choke at the exit.

Best regards

Morten

 

[ghamsa]

The operating condition of the 16" mathane line at the exist of 3" branch meet the "chocked" flow conditions. Therefore, I will use the relieve valve sizing cals at sonic velocity to find out the amount of flow through the 3".

Thanks Morten the hint.