Pump Technology Details

External Gear – Cavity Style

Consists of two or more rotating gears which mesh together. One of the gears is turned by a power source and drives the other gear(s). The spaces between the gear teeth carry the fluid from the inlet to the outlet. The gear mesh point prevents the fluid from returning to the inlet. Gear pumps are available in cavity and suction shoe styles, both of which provide pulseless delivery.

 

External Gear - Suction Shoe Style

Our trademark suction shoe pressure-loaded gear pump design features a “suction shoe” that allows the pump to self-compensate for wear. Suction shoe pumps maintain high-volumetric efficiency, even at elevated pressures. Additional benefits include near-zero slip for accurate metering, long life, and more stable performance as pump components wear or thermally expand.

 

Centrifugal

Centrifugal pumps offer a reliable, simple, long-lasting design for higher flow applications. Using the unique magnetic drive technology, centrifugal pumps provide excellent chemical resistance and energy-efficient fluid delivery. Integrated impeller and magnet assemblies reduce the number of rotating parts to maximize pump life.

Centrifugal pumps consist of an impeller rotating within a casing. Liquid directed into the center of the rotating impeller is picked up by the impeller vanes and accelerated to a high velocity. When the liquid in the impeller is forced away from the center of the impeller, a reduced pressure is produced and consequently more liquid flows forward. There is no closed volume, as in a positive displacement pump, therefore producing a steady flow through the impeller. The pump basically increases the Bernoulli head of the flow between the eye and the exit of the pump.

 

Pumps Technology Summary

Advantages & Limitations External Gear Pumps Centrifugal Pumps
Maximum Flow Rate 42 L/min
(11.1 gpm)
(higher possible)
27 L/min
(7.1 gpm)
Volume Displacement per Revolution .017 ml 3 ml
Drive Speed rpm (maximum) 6000 10000
Maximum
Differential
Pressure
8.6 bar
(125 psi)
(higher possible)
~14 meters
head
(~46 ft head)
Accuracy and Repeatability high n/a
Autoclavability / Sterility not with PTFE gears not with PTFE components
Calibration / Recalibration frequent low
frequency
Chemical Inertness high high
Corrosion Resistance good good
Cross-Contamination yes
(thorough flushing is required)
yes
(thorough flushing is required)
Dead Volume very low low
Direct Contact with Mechanical Parts
of the Pumphead
yes yes
Advantages & Limitations External Gear Pumps Centrifugal Pumps
Run Dry no no
Fittings hose barb
or screw coupling
hose barb
or screw coupling
Flow Rate Sensitivity to Differential Pressure low very high
Interchangeability
of Pumpheads
easy easy
Leakage Susceptibility low low
Maintenance (Time and Cost) medium (service kits) medium (service kits)
Multi-Channel Systems no no
Pulsation Ratio very low n/a
Pumping of High Viscosity Liquids yes no
Pumping of Suspensions, Sludges and Particles yes yes
Self-Priming yes no
Shearing Forces moderate low
Siphoning Effect When Pump Is Stopped yes yes
Suction Lift dry: ~1.52 m (5 ft)
wet: ~3.96 m (13 ft)
n/a

See Pump Overview.

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