Customers in today’s combination sewer cleaner market have two choices with which to generate vacuum: centrifugal fan or positive displacement blower. This column is not intended to sway, discount or condemn either method, but rather dispel the myths long associated with both vacuum methods and components. Neither fans nor PDs were originally intended for the sewer cleaner market, but both were designed to convey. To better understand how they ended up in this market you must first learn a little history.
Positive displacement
The positive displacement machine was invented around 1860 as a “more efficient” water wheel. Made of wood, it was
