Pressure Drop In Vacuum Lines
Calculate the pressure losses as if the system is at Standard conditions and correct the result for the reduced pressure.
Michael Reid. ■
Vacuum Friction Loss
Hi jitenprocess,
Yes - of course you can - if you understand the basis of the formulae.
1 - Gases are compressible, or expandable - according to the Gas Laws. Depends on the pressure drop. You could get shock waves develop, which would limit flow to 'critical' velocity.
2 - Is there any vapour involved? That can change your Temperature effects with latent heat evaporation.
3 - If pressure losses are small, you can use Darcy formula and chart - or use the Churchill equation [see www.cospire.com / Engineering Tips / Bulk Gases http://www.cospire.com/koviewer.aspx?id=13884 ]
The spreadsheet is set up to do Darcy calculations for you - just check the units to make sure you get the correct numbers.
4 - I will post another spreadsheet on the www.cospire.com / Engineering Tips wiki site to allow you to take into account compression/expansion effects.
5 - Remember - there is no such thing as a 'Perfect Gas'. Each gas is unique, with properties to suit its application. While they follow the crude mathematics of the Gas Laws, there are differences in behaviour in detail.
Have fun - John.rz ■
Visit
You can visit www.jdvalves.com for details. ■
Pressure drop in vacuum lines
Dear all,
I need some information
how to calculate pressure drop for vacuum lines, for pressurised gas/liquid line we use darcy's equation, but can it be used for vacuum lines also?
can i use established 'K' values and equivanlant length values for calculation of pressure drop of fittings under vacuum?
Does pressure have any relation in pressure drop in line directly, i guess there is no relation of fluid pressure which is there in line on the pressure drop. (only inlet and outlet back pressure have relation)?
Awaiting reply..... ■