Pumps

Question 1

What does drawdown refer to when operating a well and why should you keep accurate drawdown records?

Answer 1

• Drawdown level is the elevation difference between static & pumping levels

Records
* Show the loss of pumping efficiency along with records of flows & pressures
*Shows drawdown levels to evaluate condition of the well
*Helps determine proper depths for bowls
* Shows when preventive maintenance or repairs were last performed

Question 2

What is packing, and what does it do? What is a packing gland, and what are the correct procedures to follow in replacing and adjusting the packing in a centrifugal pump

Answer 2

• Made out of braided animal, flax, plant mineral, or synthetic material
• Impgrenated with some type of lubricant

PACKING GLAND
*A device used to seal around a reciprocating or rotating shaft or spindle. A malleable packing compound is forced into place by an adjustable packing nut or similar arrangement. This enables the seal or packing to be tightened to suit the operating conditions and allows subsequent adjustment to account for wear.

PACKING PROCEDURE
* Remove old packing, never stack on top of old
* Cut in scarf or butt cuts
*Cut 1/16 - 1/8 shorter than shaft circumference
* Lubricate 1st ring & seat at the bottom of the stuffing box
* Stagger rings 90 degrees
* Line lantern ring with seal water
* Finger-tight adjustment nuts

Question 3

What would be the probable cause of a severe vibration when a pump is first started?

Answer 3

• Misalignment between motor and pump shafts (coupling alignment)

Question 4

What is the difference between a velocity pump and a positive displacement pump and what would be the best applications for each? What valving precautions should be taken with each

Answer 4

POSITIVE DISPLACEMENT PUMP
* Suction and discharge valves must be open all the way
* Used mainly for chemical dosing
* Not velocity-type pumps

Question 5

How can a ball bearing failure in a pump shaft bearing generally be first detected?

Answer 5

• Bearing failure is first detected by a change in the operating sound of the pump and vibration

Question 6

What is the purpose of the curved diffuser vanes on the inside of a pump volute?

Answer 6

• Diffuser vanes convert velocity to pressure

Question 7

What would be the advantage of starting and stopping a centrifugal pump against a closed discharge valve? What precautions should be taken when opening and closing the discharge valve?

Answer 7

• A check valve prevents the shaft from spinning backward and causing damage to the pump
• If no check valve, you can start and stop a pump with the discharge valve closed to prevent water hammer by opening it slowly

Question 8

What effect could over-lubrication of grease-packed bearings have on a pump shaft?

Answer 8

OVER GREASING
* Grease acts like an insulator, holding in heat, causing premature bearing failure

Question 9

What are the three different designs of impellers in relation to shrouds that are used on centrifugal pumps?

Answer 9

• Open
• Semi-open
• Closed

Question 10

Describe the following terms: head loss, friction head loss, static head, dynamic head, total dynamic head, suction head, and suction lift

Answer 10

HEAD LOSS
* The head, pressure, or energy (they are the same) lost by water flowing in a pipe or channel as a result of turbulence caused by the velocity of the flowing water and the roughness of the pipe, channel walls, or fittings.

FRICTION HEAD LOSS
*Friction Head, also known as Friction Loss: As water flows through your discharge pipe, friction is created, from water rubbing against the inside of the pipe. This slows down the water flow, and your pump must overcome this friction.

STATIC HEAD
*The vertical distance (in feet or meters) from a reference point to the water surface when the water is not moving. Also see the dynamic head, dynamic pressure, and static pressure.

Question 11

What is a hydraulic grade line and how can it be determined

Answer 11

• The surface or profile of water flowing in an open channel or a pipe flowing partially full. If a pipe is under pressure, the hydraulic grade line is that level water would rise to in a small, vertical tube connected to the pipe.

Question 12

What advantages does packing have over mechanical seals and vice-versa

Question 13

What is the main cause of inefficiency in pumps and motors

Answer 13

• Wear is the main cause of loss in pumping efficiency

Question 14

Identify the following parts of a centrifugal pump along with the purpose of each: impeller, wear rings, shaft sleeves, seal water, lantern ring, volute, concentric reducer, and eccentric reducer

Question 15

What effect will water running backward through a centrifugal pump have on the pump and how can it be prevented

Question 16

What is the purpose of “priming” a centrifugal pump

Answer 16

• priming displaces the air in the volute case
• Helps the pump create suction so the pump will pump
• It also helps reduce cavitation

Question 17

What type of oil should be used for a culinary well pump

Question 18

What is a multistage pump and what does the addition of stages do to the discharge

Question 19

What is cavitation, how is it caused, and how can it be prevented

Question 20

What purpose do air and/or vacuum release valves serve on well casings

Question 21

What is a sanitary seal and what purpose does it serve on a wellhead

Question 22

What are the functions of a well casing and well casing perforations

Question 23

What precautions should be taken before starting a water-lubricated pump

Question 24

How does the impeller move water from the suction to the discharge side of the pump

Question 25

Explain the proper maintenance and alignment techniques for pump couplings

Question 26

What maintenance recommendations should one follow when servicing a pump

Question 27

After repairs have been done on a pump, what is the last step before putting it back in service

Question 28

What is the proper procedure for starting a pump

Question 29

What is a pump curve and what are the different things that are shown on it