pump troubleshooting

PUMP TROUBLESHOOTING

Brian GongolDJ Gongol & Associates, Inc.

November 4, 2015

Nebraska AWWA Fall ConferenceKearney, Nebraska

Quick survey

Are you here for water, wastewater, or both?

Sir Arthur Conan Doyle (as Sherlock Holmes)

"Once you eliminate the impossible,whatever remains, no matter how improbable,

must be the truth."

Handout

Pump troubleshooting flowchart

All pump problems are either mechanical...

...or hydraulic

Secondarily, they are either internal...

...or external to the pump

How to tell a mechanical problem

Take away the water

How to tell a hydraulic problem

Take measurements

Mechanical problems - internal to the pump

Bearings

Seals

Packing

Tightness of fit

Suction flap valves

Debris

Internal rubbing

Friction

Mechanical problems - external to the pump

Motors

Controls

Alignment

Balance

Transmission

Belts

Sheaves

Couplings

Valves (throttling)

Valves (isolation)

Valves (air-release)

Piping

Rotation

Jay-Z had 99 problems

We've come up with about 50...and this is halftime

Hydraulic problems - internal to the pump

Recirculation

Clearances

Wearplate wear

Wear ring wear

Volute wear

Impeller wear

In at least three flavors...

Chemical attack

Abrasion

Cavitation*

Cavitation damage happens inside the pump...but it's almost always caused outside the pump

Hydraulic problems - external to the pump

Suction side or discharge side

The two flavors of external hydraulic issues

Hydraulic problems - external - suction

NPSH

NPSHa (net) = Atmospheric pressure- vapor pressure- safety factor- total dynamic suction lift- NPSHr for the pump

Atmospheric pressure

Heat/vapor pressure

Air entrainment

Air in high spot

Turbulence

Vortexing

Minimum submergence

Plugged suction

Debris

Never underestimate what a storm can do...and deposit in your wetwells

Horizontal runs

Valves

Leaks

Not water getting out,but air getting in

Changes to fluid properties

For instance...

Gases in solution

Surfactants

Viscosity

Specific gravity

Froth/foam/bubbles

Hydraulic problems - external - discharge

Handout

Engineering data booklet

Valves

Leaks/breaks

Sediment

Debris

Changes to effective pipe diameter

Caused by...

Air

Ice

Corrosion

Scaling

Buildup

Tools to assist in your investigation

Impeller condition: Excess wear

Impeller condition: Suction cavitation

Impeller condition: Discharge cavitation

Shaft breakage

Seal failure

Strange or unwelcome noises

Strange or unwelcome noises

Suction cavitation

Discharge cavitation

Surges

The scream

Use all of your available senses (minus taste)

Record performance

Keep pump curves handy

Gauge readings make a huge difference

Gauge readings make a huge difference

Look in the direction of change

Was the change gradual or abrupt?

Some are dead giveaways,others just point in the right direction

Gauge case studies

Gauge case studies

The prime that took forever

Gauge case studies

Gauge case studies

The prime that took forever The hole in the suction line

Gauge case studies

Gauge case studies

The prime that took forever The hole in the suction line The plugged suction

Gauge case studies

Gauge case studies

The prime that took forever The hole in the suction line The plugged suction

The forcemain failure

Gauge case studies

Gauge case studies

The prime that took forever The hole in the suction line The plugged suction

The forcemain failure The sedimentation

inclination

Gauge case studies

Gauge case studies

The prime that took forever The hole in the suction line The plugged suction

The forcemain failure The sedimentation

inclination The bubble, bubble, toil,

and trouble

Gauge case studies

Gauge case studies

The prime that took forever The hole in the suction line The plugged suction

The forcemain failure The sedimentation

inclination The bubble, bubble, toil,

and trouble The surge-and-slam

Gauge case studies

Always divide and conquer

Questions?

Thank you for coming!

Thank you for your attention!

Contact us anytime with questions

Brian Gongol DJ Gongol & Associates 515-223-4144 info@djgongol.com

References:

Photo: Mechanic tightening nut (public domain) http://loc.gov/pictures/resource/fsac.1a35263/

All other photos are original work by and copyright reserved to Brian Gongol