Maximizing venturi vacuum pump

[William Burleson]

I have a venturi gas vacuum pump on the the end of an exhaust as an example. The exhaust spills out at 2.5cfm and 2 lbs. On a average of venturi efficiency, how much cfm at what pressure (or ratio alike) would be needed to eject the exhaust gas to near vacuem?
As a secondary question, what would evacuate the exhaust faster, a high pressure low cfm input, or a low pressure high cfm input?
As a third question (sorry for so many), how would the venturi effect the sound as the exhaust is lowered in temperature and pressure and then gained in pressure?

 

[nbryan5]

The answer to your first question depends on the exact requirements of your system. In general, a venturi pump's efficiency is dependent on the ratio of the inlet pressure to the outlet pressure. Generally, a higher pressure differential will result in a more efficient operation. The exact amount of CFM and pressure needed to achieve a near vacuum will also depend on the size of the exhaust pipe and the characteristics of the venturi pump.As for the second question, it depends on the characteristics of the venturi pump. Generally, a high pressure and low CFM input will result in a faster evacuation, but this may not always be the case depending on the design of the venturi pump.Finally, as the exhaust is lowered in temperature and pressure, the sound of the exhaust should be reduced due to the lower pressure. However, once the exhaust is increased in pressure, the sound should increase again.