[bhaskaran]

i want to design vacuum pump for my drying.How to select the followings
i)Pump capacity ? (Any formula is available)
ii)How to do line sizing for vauum application

[eugenedakin]

Hello bhaskaran,

Here are some formula's (fairly generic) for vacuum pump sizing:
http://www.liquidcontrol.com/etoolbox/vacuum.html

Each application for vacuum applications are usually quite unique (as most applications are). 

It is usually a blend of mathematics (supplied above) and experience (which usually has strengths and failures associated with it).  Do the best that you can.

Sincerely,

Eugene