Equipment Flashcards
Factors that can cause centrifugal pump cavitation
□ Too high suction lift
□ Partially plugged suction piping
□ High water temperature
□ Undersized suction piping
□ Partially closed suction valve
Distributes seal water uniformly around the pump shaft.
Lantern ring
“Rule of thumb” for leakage rate from pump packing.
One drip / second
The function of a shaft sleeve
Replaceable wearing surface that protects the pump shaft
A worn centrifugal pump impeller will result in this.
- Pump efficiency is reduced
- Pump output (pressure and flow) is reduced
This will occur if air is allowed to enter a centrifugal pump volute case.
The pump can become air-locked and refuse to pump.
Sludge greater than 1 % TS requires this kind of pump
Positive displacement pump
Key factor in operating any positive displacement pump.
Never operate the pump with a closed discharge valve.
Positive displacement pumps.
- Diaphragm
- Progressive cavity, Moyno™
- Piston
The way to correct wrong rotation in a three-phase motor.
Switch any two of the three electrical leads to the motor.
This pump shaft sealing mechanism utilizes a rotating carbon unit and a stationary ceramic.
Mechanical seal
The flow of electric current is measured in this unit.
Amperes or “amps”
Materials used to make pump packing.
Hemp, flax, jute, cotton, teflon,™ and graphite
These conditions can cause an operating centrifugal pump to fail to deliver water.
- Plugged impeller
- Closed suction or discharge valve
- Airlock in pump volute case
- Loss of prime
- Plugged suction or discharge piping
- Impeller not connected to shaft
Over lubrication of a bearing can result in this
Bearing overheating and failure
These symptoms may indicate bearing failure.
- Vibration
- Bearing noise
- Increase drive motor amperage draw
- Excess bearing temperature
The most common type of electric drive motor in the wastewater industry.
Synchronous speed
Typical causes of electric motor failure.
- Dirt
- Moisture
- Overload caused by bearing failure
Maximum practical pump suction lift.
25ft
Function of pump wearing rings
□ Prevent loss of efficiency due to pump internal recirculation
□ Replaceable, they protect the pump impeller and volute case from wear and damage