The A320 is a patented impeller by Lightnin. It has 3 blades and is called by Lightnin a
fluidfoil impeller. It is considered an down-pumping axial flow impeller, because under
turbulent conditions the discharge of the fluid is parallel to the shaft (0 degrees). As you
can see from the table below, as the Reynold's number decreases the flow discharges at a greater
Turbulent Power Number Np=0.64, Flow Number
The A320 was designed to operate in the turbulent and transitional ranges. The high solidity
of the blades makes it work even in very high viscosity. As the viscosity increases and the
Reynold's Number (Re) decreases, the starts to become more radial, as do all axial flow impellers.
The table below shows the discharge angle as a function of Re.
If you flip an A320 upside-down and rotate it counterclockwise, the flow pattern is upward.
If the A320 is built to be an up-pumper, but to operate in the clockwise direction, the
impeller is called the A340.
We think that the up-pumping flow pattern has many advantages. Some people call it and
up-draft or an up-flow pattern. The design of up-pumping is so different from down-pumping
or down-flow that most people will not be able to optimize it. We will be bringing articles
about this soon. In the meantime, look at our references and go to your library for those of
you that need to know now.