7/31/2019 All Types of Pump

1/5

Diaphragm pumps are also classified as positive displacement pumps because the diaphragm acts as

a limited displacement piston

Centrifugal

Centrifugal pumps basically consist of a stationary pump

casing and an impeller mounted on a rotating shaft. The

pump casing provides a pressure boundary for the pump

and contains channels to properly direct the suction and

discharge flow.

The pump casing has suction and discharge penetrations for

the main flow path of the pump and normally has small

drain and vent fittings to remove gases trapped in the pump

casing or to drain the pump casing for maintenance

Plunger/Piston Pumps

Piston pumps and plunger pumps are reciprocating

pumps that use a plunger or piston to move media

through a cylindrical chamber. The plunger or piston is

actuated by a steam powered, pneumatic, hydraulic, or electric

7/31/2019 All Types of Pump

2/5

drive. Piston pumps and plunger pumps are also called well service pumps, high pressure pumps, or

high viscosity pumps.

Piston pumps and plunger pumps use a cylindrical mechanism to create a reciprocating motion along an

axis, which then builds pressure in a cylinder or working barrel to force gas or fluid through the pump. The

pressure in the chamber actuates the valves at both the suction and discharge points. Plunger pumps are

used in applications that could range from 70 to 2070 bars. Piston pumps are used in lower

pressure applications.

Gear Pumps

There are several variations of gear pumps. The simple

gear pump shown in the illustration here, consists of two spur

gears meshing together and revolving in opposite directions

within a casing. Any liquid that fills the space bounded by two

successive gear teeth and the case must follow along with the

teeth as they revolve.

When the gear teeth mesh with the teeth of the other gear, the

space between the teeth is reduced, and the entrapped liquid is

forced out the pump discharge pipe. As the gears revolve and the teeth disengage, the space again opens

on the suction side of the pump, trapping new quantities of liquid and carrying it around the pump case to

the discharge. As liquid is carried away from the suction side, a lower pressure is created, which draws liquid

in through the suction line.

There are no valves in the gear pump to cause friction losses as in the reciprocating pump. The high impeller

velocities, with resultant friction losses, are not required as in the centrifugal pump. Therefore, the gear

pump is well suited for handling viscous fluids such as fuel and lubricating oils.

Sanitary Lobe Pumps

Lobe pumps are used in a variety of industries including, pulp and paper,

chemical, food, beverage, pharmaceutical, and biotechnology. They are

7/31/2019 All Types of Pump

3/5

popular in these diverse industries because they offer superb sanitary qualities, high efficiency,

reliability, corrosion resistance, and good clean-in-place and sterilize-in-place (CIP/SIP)

characteristics.

These pumps offer a variety of lobe options including single, bi-wing, tri-lobe (shown), and multi-lobe.

Rotary lobe pumps are non-contacting and have large pumping chambers, allowing them to

handle solids such as cherries or olives without damage. They are also used to handle slurries,

pastes, and a wide variety of other liquids. If wetted, they offer self-priming performance. A

gentle pumping action minimizes product degradation. They also offer reversible flows and can

operate dry for long periods of time. Flow is relatively independent of changes in process pressure, so

output is constant and continuous.

Rotary lobe pumps range from industrial designs to sanitary designs. The sanitary designs break down

further depending on the service and specific sanitary requirements. These requirements include 3-A,

EHEDG, and USDA.

Regenerative Turbines

The primary difference between a centrifugal and a regenerative

turbine pump is that fluid only travels through a centrifugal impeller

once, while in a turbine, it takes many trips through the vanes.

Referring to the cross-section diagram, the impeller vanes move within the

flow-through area of the water channel passageway.

Once the liquid enters the pump, it is directed into the vanes, which push the

fluid forward and impart a centrifugal force outward to the impeller

periphery. An orderly circulatory flow is therefore imposed by the impeller vane, which creates

fluid velocity. Fluid velocity (or kinetic energy) is then available for conversion to flow and pressure

depending on the external systems flow resistance as diagrammed by a system curve.

Screw Pumps

7/31/2019 All Types of Pump

4/5

Screw pumps are rotary, positive displacement pumps that can have one or more screws to transfer high or

low viscosity fluids along an axis. A classic example of screw pump is the Archimedes screw pump

that is still used in irrigation and agricultural applications.

Although progressive cavity pumps can be referred to as single screw pumps, typically screw pumps have

two or more intermeshing screws rotating axially clockwise or counterclockwise. Each screw thread is

matched to carry a specific volume of fluid. Like gear pumps, screw pumps may include a stationary screw

with a rotating screw or screws. Fluid is transferred through successive contact between the housing and

the screw flights from one thread to the next. Geometries can vary. Screw pumps provide a specific

volume with each cycle and can be dependable in metering applications.

Hose Pumps

Hose pumps are self-priming rotary positive displacement pumps that

operate on the peristaltic principle. The pump consists of three major

parts: hose, housing and rotor. The hose is placed in the tubing bedbetween

the rotor and the housingwhere it is occluded (squeezed).

The rollers or shoes on the rotor move across the hose, pushing the fluid. The

tubing behind the shoe or roller recovers its shape, creating a vacuum and

drawing fluid in behind it. A pillow of fluid is formed between the rollers

specific to the interior diameter (ID) of the hose and the geometry of the

rotor. Flow rate is determined by multiplying speed (rpm) by the volume of the pillow. This pillow

volume is consistent, even under a wide range of viscosities

Air-Operated Pumps

Air operated diaphragm pumps (AOD) or Air-Driven Pumps are

ideal for moving sludge and slurries. Solids-laden fluids like sludge

and slurry are hard to move -- unless you're using an air operated

diaphragm pump.

7/31/2019 All Types of Pump

5/5

Air is driven into the bottom of the air cylinder, raising the piston inside and lifting the diaphragm. As the

diaphragm is raised, the check valve ball on the intake side is lifted and liquid flows into the pump. When

the piston has risen to the top, the pump cavity is filled and the pump is ready for discharge.

Compressed air is then forced into the top of the diaphragm chamber, pushing the diaphragm down and

evacuating the pump cavity. The check-valve ball on the discharge side is lifted and the pump is ready for

the next cycle.

Vane Pumps

The simplest vane pump is a circular rotor rotating inside of

a larger circular cavity. The centers of these two circles are

offset, causing eccentricity. Vanes are allowed to slide into and out

of the rotor and seal on all edges, creating vane chambers that do

the pumping work.

On the intake side of the pump, the vane chambers are increasing

in volume. These increasing volume vane chambers are filled with

fluid forced in by the inlet pressure. Often this inlet pressure is nothing more than pressure from the

atmosphere. On the discharge side of the pump, the vane chambers are decreasing in volume, forcing fluid

out of the pump. The action of the vane drives out the same volume of fluid with each rotation. Multistage

rotary vane vacuum pumps can attain pressures as low as 10-3 mbar (0.1 Pa).

Vane pumps are used for liquid transfer applications from chemicals to liquefied gases. Vanes

extend from slots in the rotor; sweeping liquid through a cam-shaped cavity. The vanes provide

very low slip and high volumetric efficiency.