One of the things I like about back pack blowers, is that unlike many other power
equipment products, their performance can be measured and compared. Never the less
it can still become confusing as manufacturers will often throw out irrelevant numbers
as will be explained below.
The measure. CFM (cubic feet per minute) and MPH (Miles per Hour) are the measures
of blower performance. Manufacturers can easily increase MPH by making the pipe
smaller but this will decrease CFM. And they can easily increase CFM by making the
pipe bigger but this will decrease MPH. It’s not unusual to see manufacturers list
CFM at the housing and MPH at the end of the pipe. But measuring CFM with the with
the blow pipe removed is a meaningless exercise, other than to have a big number
to write down on a spec sheet. What matters and what you are looking for is CFM
and MPH measured at the end of the pipe.
How do you measure performance with two different numbers. You can crate a blowing
performance index by multiplying the two together. For example: