Specifications

4
Operation
In the trunnion-ported BPB, BMB and
BMC pumps, fluid enters the pump at
the outer drive gear side of the pump. A
passage has been drilled from the inlet
port up through the front plate into the
center plate gear pocket. Fluid flows into
the gear pocket and fills the gear tooth
volumes. As the gears rotate, the fluid is
transported around the outer diameter of
the gear pocket to the discharge side.
As the gears mesh together, the fluid is
displaced back down a passage drilled
into the rear plate and out the discharge
port at the rear side of the pump.
In rear-ported BPB, BLB and BXB
pumps, fluid enters the pump through a
port drilled into the rear side plate (the
side opposite the outer drive gear/shaft).
The fluid again fills the exposed gear
tooth volumes and is transported around
the outer diameter of the gear pocket.
As the gears mesh, the fluid is displaced
out through the discharge port that is
drilled alongside the inlet port in the rear
plate.
Since Zenith
®
pumps are not self-
priming, a flooded suction is usually the
minimum inlet pressure required. How-
ever, when high-viscosity fluids are
used, more time is required to fill the
tooth volumes. As a result, the inlet
pressure must be increased or the gears
must rotate at a slower speed to ensure
complete volume filling and to prevent
cavitation.
Zenith
®
pumps rely on the metered
fluid for lubrication of internal bearing
areas. The pump should never be
allowed to run dry or be allowed to run
with non-lubricating fluids such as water.
Because of close clearances in the
bearing areas, lack of sufficient lubrication
can cause pump seizure and possibly
catastrophic failure.
Under extreme conditions, slip may
occur across the face of the gears from
in between the high-pressure side to the
low-pressure side. Pump efficiency
depends on four factors: fluid viscosity,
pump speed, differential pressure and
gear clearances. Under reasonably
stable operating conditions, slip is
repeatable and predictable, and
pump operation can be adjusted to
compensate.
The Zenith
®
B-Series pumps are
designed for low-temperature operation.
As such, the maximum operating tem-
perature should not exceed 300° F.
When operating at temperatures above
ambient, heat jackets should be used,
and pumps should be heated slowly
and uniformly.
The 400-Series stainless steels used
in the construction of the B-Series
pumps provide sufficient corrosion
resistance for most standard chemical
processes. The material hardness will
provide a high degree of wear resistance
as well. However, processes involving
corrosive or abrasive fluids should
always be approved by Zenith
®
.