2 replies to this topic

[kangas]

I have a storage of gas which is at 9 mbar. I have a diameter of 18mm pipe. When I measure flow at 9 mbar is at 9 m3/h. How to estimate what size of pipe I need to reduce at to get 1m3/h?

Is it realistic to just use Q= A x v? or do I need to take into account pressure also? Is there a correlation with pressure I can use? 

 

P.S. Pressure drops over time due to emptying of the storage thus flow rate changes.

[breizh]

Hi,

A sketch please.

Why don't you use a valve or a rotameter to manage the flow rate?

 

Breizh 

[snickster]

The continuity equation has nothing to do with it.  The flow is determined by the upstream pressure and pipe size.  The the greater the flow, the greater the pressure drop for a given line size, the greater the upstream pressure the greater the flow.  When overall pressure drop at flow equals upstream available pressure steady state constant flow occurs.  If you reduce the line size at some point you will  achieve the flow you want (but pipes are not available in continuously varying diameter so you can't get the exact flow/pressure drop you are looking for).  Also if both upstream and downstream pressures vary you 're not going to be able to maintain the flow you really want. Also as you go over 60 ft/sec in pipe there is a lot of noise generated so best to size gas flow pipe based on 60 ft/sec as is normally done.   Like Brieze said it is best to use rotometer with throllting valve such as a needle valve or globe valve, with same piping.

Edited by snickster, 23 June 2023 - 07:47 PM.