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PUMPS

Pumping Basics

Centrifugal Pumps

Positive Displacement Pumps

Pumping BasicsPUMPS deliver energy (lb-ft, lb-in, joules. Etc.) to a given

volume (cu.in., cc. gallon= 231 cu.in., liter= 1000cc) Pressure is usually thought of as force/area, but is also energy/volume

(lb-in/in3 = lb/in2 or psi) Pressure x Flow is power: energy/vol x vol/time PSI x GPM = HP; Pascals x m3/sec = watts 1714

Energy Gain (ib-in)per unit volume (in3)

= lb/in2 (psi)

Pumping Basics HEAD, energy per pound of liquid, commonly expressed in feet representing the

vertical height of a static column of liquid corresponding to the pressure of the fluid at the point in question

In general, a liquid may have three kinds of energy. That is, the capacity to do work may be due to three factors: Potential Head - (energy of position, i.e. the work obtainable in dropping a

vertical distance) Hz is directly measured in feet Static Pressure Head - (energy per pound due to pressure, i.e. the height to

which a liquid can be raised by a given pressure) Hp(ft) = [PSI x 2.31] / SG Velocity Head - (kinetic energy per pound, i.e. the vertical distance a liquid

would have to fall to acquire velocity V) Hv(ft) = V2 / 2g

P 1 psi P 1 psi P 1 psi

2.31 ft

H2OSG= 1

GasolineSG= 0.7

MolassesSG= 1.5

1.54 ft

3.3 ft

VelocityV

HV= V2

2g

P

Pumping Basics Total Pump Head, is the difference between the energy per lb

on the discharge side vs. the suction side of a pump (expressed in feet) Zs & Zd are the elevation (ft) to the point of suction or discharge measure

from thr datum plane (usually through the center of the pump’s inlet port) Hfs & Hfd are the friction losses (in feet) in the direction of flow to/from the

pump suction & discharge parts to the respective measuring points

H= ( Pd – Ps ) x 2.31/SG

+ ( Zd – Zs )+ ( Vd2 – Vs2 )

2 g+ ( Hfd – Hfs )

P

Ps

Pd

Vs Zs

Zd

Vd

Hfs

Hfd

Pump Types

Kinetic vs. Positive Displacement

Centrifugal vs. Special Effect e.g., Jet Pump (Eductor)

Radial vs. Axial vs. Mixed Flow

Centrifugal (Radial Flow)IMPELLER

EYE

VOLUTE

DISCHARGE

SUCTION

(Radial) Centrifugal Pump Varieties

Impeller construction Horizontal vs. Vertical

Closed Impeller

Semi-closed Impeller

Open Impeller

(Radial) Centrifugal Pump Varieties Single suction

Multi-stage centrifugal pumps

Double suction

P

Centrifugal Pump Characteristics

FLOW (GPM)

PRESSURE (PSI)

IDEAL

ACTUAL

PUMP CHARACTERISTIC

SYSTEM CHARACTERISTIC

SHUT-OFF HEAD (no flow)

OPERATING POINT

PUMPSYSTEM

P

Centrifugal Pump Characteristics

FLOW (GPM)

PRESSURE (PSI)

IDEAL

ACTUAL

PUMP CHARACTERISTIC


SHUT-OFF HEAD (no flow)

OPERATING POINT

PUMPSYSTEM

PUMP CHARACTERISTIC (higher RPM)

SHUT-OFF HEAD (no flow) PUMP CHARACTERISTIC

(lower RPM)

Pump TypesKinetic vs. Positive Displacement

Reciprocating vs. Rotary

Fixed volume pushed through each stroke (recip) or revolution (rotary)

P

Pos. Displ. Pump Characteristics

FLOW (GPM)

PRESSURE (PSI)

IDEALACTUAL

PUMP CHARACTERISTIC


OPERATING POINT

PUMPSYSTEM


FLOW (GPM)

PRESSURE (PSI)

IDEALPUMP

SYSTEMACTUAL

P

?

Relief Valve

Relief Valve setting

Through Pump

Into System RecircRecirc


FLOW (GPM)

PRESSURE (PSI)

IDEALPUMP

SYSTEMACTUAL

P

Relief Valve

Relief Valve setting

Through Pump

Recirc

Increase Pump Speed

Reciprocating Pumps Double acting Single acting

one cycle

one volone vol

one cycle

one volone voltwo volstwo vols

GPM= VOL(gal) x CYCLE/MIN GPM= 2 x VOL(gal) x CYCLE/MIN

single or double actinghorizontal or vertical

Reciprocating Pumps Simplex (one piston) Duplex

Steam End Liquid End

Slide Valve Valve Chest


Triplex & Multiplex

Motor or Engine driven

Multiple (3 or more) plungers (pistons)


Reciprocating Pumps Diaphragm Pump (air operatated)

DISCHARGE

SUCTION

SHUTTLE VALVE

AIR SUPPLY

EXHAUST

Rotary PumpsGear Pump (external gear)

(Internal) Gear Pump

= volume betw adj teeth

in3 x # teeth x 2 gears x RPM231 in3/gal

= GPM

Driving Gear

Driven Gear

Driving Gear

Driven Gear

Rotary Pumps Gear Pumps Lobe Pumps

One rotor does not drive the other

Timing Gears required

Two, three, or more lobes possible:2 lobes = “rotating piston”

Rotary Pumps Gear Pumps Lobe Pumps Screw Pumps

Double-screwDouble-endwith Timing Gears

Triple-screwDouble-endwithout Timing Gears

Double-screwSingle-endwithout Timing Gears

Rotary Pumps Gear Pumps Lobe Pumps Screw Pumps Sliding Vane Pumps

Rotary Pumps Gear Pumps Lobe Pumps Screw Pumps Sliding Vane Pumps Liquid Piston Pump

Circulated water acts as piston

Air drawn in to create vacuum

Used to prime centrifugal pump

Pumping OperationsStarting Procedures

Securing Procedures

Sytem Operation

General Considerations

• Insure that suction side piping is lined up as intended. All suction connections should be checked to prevent drawing from some unintended location.

• Insure that discharge piping is lined up as intended. All discharge connections should be checked to prevent inadvertent discharge to an unintended space or overboard.

• Be familiar with normal operating parameters (pressures, temperatures, etc.) so that abnormalities may be detected promptly.

Centrifugal Pumps

Rotary (P.D.) Pumps

Steam Recip. PumpsSUPPLYSUPPLY

EXHAUSTEXHAUST

DISCHARGEDISCHARGE

SUCTIONSUCTION

STEAM END

LIQUID END

Turbine Feed Pumps

SUPPLYSUPPLY

EXHAUSTEXHAUST

DISCHARGEDISCHARGE

SUCTIONSUCTION

PRESS PRESS REG V.REG V.

RECIRCRECIRCDRAINDRAIN

L.O. SYSTEML.O. SYSTEM

Turbine Feed Pumps

DRAINDRAIN

DISCHARGEDISCHARGE

SUPPLYSUPPLY

EXHAUSTEXHAUSTSUCTIONSUCTION


SUCTIONSUCTION

MAINMAIN AUXAUX

RECIRCRECIRCL.O. L.O. PUMPPUMP

O/S O/S TRIPTRIP

Turbine Feed Pumps

SUPPLYSUPPLY


SUCTIONSUCTION EXHAUSTEXHAUST

DISCHARGEDISCHARGE

RECIRCRECIRCDRAINDRAIN

L.O. SYSTEML.O. SYSTEM

Turbine Feed PumpsSUPPLYSUPPLY


L.O. supply

Fd. Pump discharge pressure

L.O. return

PILOT PILOT VALVEVALVE

OPERATING OPERATING CYLINDERCYLINDER

Press incr

Press decr

… or relax spring

… or tighten spring

Reach rod

Operating piston drops decreasing steam flow

Operating piston rises increasing steam flow

With spring tension & pump pressure balanced, steam flow is constantOverspeed trip drops operating piston & shuts off steam flow

O/S Trip

Piping systems• Example 1: (Generic) Fuel oil Transfer

Piping systems• Fuel oil Transfer Manifold

SUCTION

FILL



Piping systems• Example 2: Bilge, Ballast, Fire Main

SEA CHESTS

Piping systems• Bilge Manifolds Ballast Manifolds

Low pressure in upper chamber draws bilge water up

Stop-check prevents bilge flooding

Ballasting or deballasting possible

Piping systems• Example 2: Bilge, Ballast, Fire Main