priming and cavities

pump priming

condition of dynamic/kinetic pump (exclude submersible) to discharge liquid at soonest possible time

pump priming

process of fully submerged the pump impeller in liquid with no trapped air/ process of removing air inside the casing

no seal or continuous passageway

why is non priming pump require priming since the liquid tends to go back to the source

foot valve (intake side) check valve( discharge side)

other pump does have this type of valve to isolate liquid preventing back to source

non priming/self priming pump ( rotary and reciprocating)

this type of pumps do not require priming procedure since there is a temporary isolation inside

auxiliary priming method (a)

doesnt require any device just supply tank above pump center line

auxiliary priming method (b)

doesnt need any device just by-pass line in discharge line with check valve (isolation of liquid at discharge side)

auxiliary priming method ( c )

only use of different supply line/auxiliary lune from different source to fill pump casing

auxiliary priming method (d)

use separate pump to draw in the liquid at pump casing ( increase suction pressure that enables pump casing filled immediately)

auxiliary priming method (e)

use air ejector to draw out air at the pump casing to accelerate pumping in of liquid

auxiliary priming method (f)

use of priming tank to enhance drawing in of liquid (increase suction pressure) the liquid pressure generated in tank supplys the suction pressure

auxiliary priming method g&h

use vacuum pump (manual or automatic) to suck in liquid p and draw out air to enhance discharge/distribution of liquid

auxiliary priming method (i)

manual priming (simplest priming method) . process of directly pouring pumped liquid into casing via inlet/priming port

pressure move the fluid would be difficult because of air trapped inside

what happened when piping system doesnt have priming

immediate discharge of fluid (critical for firefighting to save lives) also increase pump efficiency with less energy consumption

what happens if has a priming

dry pump

a pump that is overheat and cause damage to the impeller,seal,bearings causing stoppage of pump

has a proper lubrication and cooling of pump

what happened when pump is filled with fluid that result smooth working operation

operate more efficiently with lower energy consumption, less wear and tear

what happened to a well primed pump

pump cavitation

it cause damage to the pumps impeller and casing, reduce pump efficiency and leads stoppage

if it is first time, the foot and check valve is defective

why kinetic pump required priming

if it is operated by foot and check valve, if the source is suction head

why priming is not required in kinetic pump

if there is static suction lift (move up liquids at 28ft or less) also no pressure loss

why does reciprocating and. rotary pump has self priming

if static suction lift is 28ft up of elevation and loss of pressure

why reciprocating and rotary oumo needs priming

pump cavitation

a destructive phenomena which formation of bubbles/vapor pockets in pump casing causing to impeller and casing damage

phenomena

a natural occurence that take place as causing factors are present

flow valve, ships/submarine propeller,turbine impeller

3 places that cavitation takes place

surface errosion that cause restriction to flow

common damage of cavitation

ABC cavitation

it begins at the eye of impeller due to low pressure and begins with formation of vapor bubbles

CD cavitation

point where lowest possible pressure inside the centrifugal pump located( point where liquid is acted upon)

CDE cavitation

cause by rapid impeller movement that cause of vapor compression to collapse(implosion)

60ksi

what pressure does implosion can reach that cause pitting erosion

pitting erosion

form of corrosion characterized as holes/cavities

output(capacity)

what is affected when impeller surface is damaged

vibration

what happened when cavitation left unchecked cause damage to bearing and eventually stoppage

suction cavitation damage

it damage the suction side if vane surface close to eye of impeller cause by large bubble formation before it reaches impeller eye

discharge recirculation cavitations damage

damge the vane tips and outer ends of front and rear shrouds bubble formation formed after the impeller eye portion

liquid vaporization/boiling

how bubble formation takes place where liquid evaporate from liquid to gas

implosion

bubble release as microjets of fluid producing shockwaves

noise & vibration

sign oof cavitation where ewuipment exhibit certain sound on repeated basis

no liquid being sucked

what type of sound does hissing/ static televesion sound

loud knocking, hammering or crackling sound

what sound produce by suction cavitation

drop in capacity /pump efficiency

sign of cavitation with formation of bubbles taking away the volume that translate into dip of its capacity

dip in its capacity

means less work, less output resulting to decrease of pump efficiency increases in energy cost

corrosion of impeller van and inner surface

sign of cacitation that vapor bubbles hit by rotating i peller that release microjets, cause pitting erosion

poor suction conditions

caused by poor pipework design

low suction pressure

cause by clogged suction pipe either suction lift is too deep, suction head is too low

pump speed is too high

cause by motor is too fast for the pump

high fluid viscosity

cause by fluid is hard to move as possibility of no fluid at all being sucked in

minimize number of bends and

make long radius elbow,

use of eccentric reducer

suction length of pipe is short as possible

suction pipe diameter is same with pump inlet connection

how to solve poor suction condition

provide strainer at suction line

schedule cleaning of. strainer

compute proper sizing of pumps and motor

how to solve low suction pressure

compute proper sizing of pumps and motor

select different kind of pump rather than centrifugal pumps

how to solve pump speed is too high

use of rotary pumps

try to heat the suction line to increase fluid flow

elmarge pipe suction diameter

how to solve high fluid viscosity

cast iron and bronze

material that can withstand 20 or more years

cast iron

can withstand high pressure force and high resistance of wear and abrasions because of exceptional tensile strength

brinze impeller

experience minimal wear and tear that contributes longevity of pump

wpecial polymeric rebuilding. & coating material

2 component coating filled with ceramic filled epoxy that reduce friction and improves against wear and tear