air evacuation flow rate help

[yoss]

I'm trying to do a calc to determine the flow velocity expected during evacuation of a dry laminate layup under vacuum bag prior to resin infusion.

i guess i can simplfy the problem down to... sealed chamber volume (0.32 m3) initialy at atmospheric pressure connected to a 200m3/hr pump via 25mm ID pipe.

any tips would be great - can i use benouli or does the flow choke (i have vague memory of this being an issue from uni dayz!)

 

[NCSUMAN]

That's tricky and will depend on what vacuum level you are drawing to. You have permability of the fabric, off gassing of materials, and other factors. Also as the level of vacuum increases it becomes more and more difficult to move the air molecules. A vacuum pump manufacturer such as Alcatel may have some information or resources.

Sounds like a noble project. Keep us posted.