Pumps and Maintenance Part One Flashcards
Where would you find information on when to lubricate a pump?
Pumps should be lubricated in accordance with the manufacturers recommendations.
What problems can develop if too much grease is used in lubricating an electric motor?
It may cause bearing problems or damage the windings.
Why should a pump with a mechanical seal never run dry?
A pump with a mechanical seal (or any other seal) should never run dry because water is required for seal operation.
What factors influence the rate of brush wear in an electrical motor?
The rate of brush wear varies with the brush pressure. At light pressures, electrical wear is dominant because the brush can jump off the rings, sparking occurs and the filming action on the ring becomes erratic. At higher pressures, mechanical wear is dominant because of high friction losses, needless heating and abrasion.
What should you check if a pump will not start?
If a pump will not start, check for blown fuses or tripped circuit breakers and then determine the cause. Also, check for a loose connection, or thermal unit.
What would you check if the flow rate from a pump is lower than expected?
You should check for something causing the reduced rate of discharge, such as pumping air, motor malfunction, plugged lines or valves, restricted suction, impeller problems, etc.
Under what conditions might a centrifugal pump be started against a closed discharge valve?
Normally a centrifugal pump should be started after the discharge valve is opened. Exceptions are treatment processes or piping systems with vacuums or pressures which cannot be dropped or allowed to fluctuate greatly while an alternative pump is put online.
What should be done before stopping an operating pump?
Start another pump (if needed) and inspect the operating pump for developing problems, required adjustments and problem conditions.
What could cause a pump shaft or motor to spin backwards?
If wastewater being pumped flows back through the pump when the pump is shut off. This will occur if there is a faulty check valve or foot valve in the system.
Why should the position (open or closed) of all valves be checked before starting the pump?
The position of all valves should be checked before starting a pump to ensure that the wastewater being pumped will go where intended and to insure an open valve on discharge line.
What is the most important rule regarding the operation of a -POSITIVE DISPLACEMENT- pump?
Never start the pump against a closed discharge valve.
What could happen if a positive displacement pump is started against a closed discharge valve?
The pipe, valve, or pump could rupture from the excessive pressure. The rupture will damage equipment and possibly seriously injure or kill someone standing nearby.
How can you tell if a new pump is delivering design flows and pressure?
Measure the flows and pressures and compare them with the pump performance curve supplied by the manufacturer.
What is the most common maintenance problem associated with water-level -FLOAT CONTROLS-?
Scum and debris interfere with their operation and must be removed from water-level float controls.
What is -CROSS CONNECTION-?
A connection between two piping systems where an undesirable water (water from water seal) could enter and contaminate a domestic drinking water supply.
