# Energy required to vacuum a cylinder

I'm trying to calculate the energy per unit length the vacuum pumps require to vacuum a cylinder with a diameter D. Which formulas should I use?

I used a typical formula for compressors and the result I got was that the air exited at 12,000 K at the end of the process! Also 500 kWh/km to vacuum a 3.3 m diameter cylinder (the initial pressure is 101,325 Pa and the end pressure is 99 Pa).

• What sort of brush head do you have? – Solar Mike Apr 13 at 18:10
• I don't know the energy head, I only have those data. – user20096 Apr 13 at 19:26
• "require to vacuum a cylinder" would be better as "require to create a vacuum in a cylinder"? – Solar Mike Apr 13 at 19:28
• Require to create a vacuum in a cylinder is certainly better, because there will be some aire left. At the beginning there are 10 tonnes of air and at the end 10 kg (using the ideal gas formula for air with a constant temperature of 292 K). – user20096 Apr 13 at 19:33
• Well, I first calculated the energy to create a vacuum in 1 m and I multiplied everything by 1,000. In 1 m here's what I have: 10 kg, 0.01 kg and 0.5 kWh/m. – user20096 Apr 13 at 19:35