I don't have the same kind of rotor mentioned in your protocol for concentrating virus, how do I know mine will work?

You do not have to use SW28 rotor or the tubes. Other rotor sizes will work. You just need to cross reference the g force and time of run for your rotor. You can use the following web sites to make the conversions: http://www.beckman.com/resourcecenter/labresources/centrifuges/rotorcalc.asp http://www.beckman.com/resourcecenter/labresources/centrifuges/runtimecon.asp Here is a paper that uses a SW32Ti rotor (19500 rpm for 2hr) to concentrate lentivirus which might be helpful: http://www.liebertonline.com/doi/abs/10.1089/hum.2006.138 There is a conversion for rpm to rcf at this website: http://insilico.ehu.es/mini_tools/rcf_rpm.php In our viral protocol to pellet the cells we recommend spinning at 3000rpm, which is equivalent to ~1000xg. For the viral concentration protocol we recommend spinning at 23,000rpm, which is equivalent to ~72,000xg.