vacuum pump selection

[aerospace2013]

Hello everyone

I'm willing to purchase a vacuum pump to use it for manufacturing composite panels using both resin infusion and vacuum bagging processes.

1. I have used a vacuum pump before from GAST and it gave me around 28inHg maximum vacuum. I don't know the model number or other specifications because I don't have it right now..etc

What should I look for in the vacuum pump? horse power? maximum vacuum? the flow rate cfm? the pressure? suitable flow rate ( delivery rate) at the maximum vacuum?
Can you please guide me how to select the appropriate vacuum pump ( with reasonable price)

for example is GAST 1023-101Q-SG608X a good option (please check attached file). but at 27inHg vacuum the cfm is almost zero, what does this mean?

2. Also, I'm confused about few terms, for example the relationship between the pressure and the vacuum in the vacuum pump ( for example a certain vacuum pump - diaphrgam vacuum pump KF manufacturing - N035AN.18 has the following specifications 4 bar pressure, 100mbar ultimate vacuum and 30l/m delivery rate)..is there any relation between the pressure and the vacuum ?

Appreciate your prompt response

 

[Compositepro]

There are vacuum bagging processes that that only require 27" or less vacuum but there are also cases, particularly non-autoclave cures that benefit from much higher vacuum levels. The pressure rating is not relevant for vacuum pump use. It just means the pump can also work as a compressor.

Higher CFM is always desirable to overcome bag leaks, and particularly to get the bag to seal initially. But large vacuum pumps a very expensive. A Shop-Vac is can be used to get most of the air volume out of a bag, then switch to the vacuum pump. If you have a very limited budget get a used pump. The best are the Duo-seal pumps. 1/2 hp, about 4 cfm should work fine. Habor Freight has new pumps that are inexpensive. Most of the less expensive, decent pumps are designed for refrgerator servicing.