Basically any fan at a given RPM will produce the same flow. There may be somedifferences, but nothing significant.
In addition most fans will produce the exact same noise at a given RPM/Flowrate. Some are slightly louder (YS Tech) while others are slightly quieter (Papst, Panaflo), but basically a fan is a fan. I just get the fastest one and drop a resistor/rheostat onto it until it performs how I need.
Badly_Wired :
Check below that line, the last digit in that series indicates which type you have. L, M, H, U for Low, Medium, High, Ultra.
http://www.panasonic.com/industrial/...aflo_axial.htm