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Well Pump Installer practice questions

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Question 1Pump and Water System Components

What is the primary function of a pressure tank in a household well system?

  1. Filters sediment before water enters the fixtures
  2. Increases the yield of a low-producing water well
  3. Stores water under precharge to limit pump cycling Correct answer.
  4. Measures the static water level inside the casing

Explanation

The tank holds water under a compressed air precharge, so a draw of water is supplied by stored volume instead of by the pump. This buffer limits start-stop cycles and protects the motor from rapid cycling.

Question 2Pump and Water System Components

In a shallow-well jet pump installation, what is the purpose of the foot valve?

  1. Removes dissolved gases from the well water
  2. Keeps the suction line primed and prevents backflow Correct answer.
  3. Measures the pumping water level in the well
  4. Regulates discharge pressure at the tank inlet

Explanation

The foot valve is a one-way valve at the bottom of the suction pipe. It holds water in the suction line when the pump stops so the jet pump does not lose prime, and it blocks backflow into the well.

Question 3Pump and Water System Components

A pressure switch marked 30/50 will do which of the following?

  1. Start the pump at 30 psi and stop it at 50 psi Correct answer.
  2. Start the pump at 50 psi and stop it at 30 psi
  3. Start the pump at 40 psi and stop it at 30 psi
  4. Maintain a constant 40 psi at the fixtures

Explanation

On a 30/50 switch the first number is the cut-in pressure and the second is the cut-out pressure. The pump starts when tank pressure falls to 30 psi and stops when it reaches 50 psi.

Question 4Pump and Water System Components

A system uses a 30/50 pressure switch. What air precharge should the pressure tank be set to?

  1. 35 psi
  2. 50 psi
  3. 30 psi
  4. 28 psi Correct answer.

Explanation

Tank precharge is set about 2 psi below the pump cut-in pressure, with the tank drained of water. With a 30 psi cut-in that gives 28 psi, so the switch responds to water pressure rather than fighting the air charge.

Question 5Pump and Water System Components

Where should the primary check valve be installed on a submersible pump?

  1. At the pressure tank inlet inside the house
  2. Inside the well seal at the top of the casing
  3. Directly on the pump discharge, above the pump Correct answer.
  4. On the suction side of the pressure switch

Explanation

The check valve mounts on the pump discharge so the riser stays full of water between cycles. This prevents backflow and backspin and keeps the pump from having to lift the whole column on every start.

Question 6Pump and Water System Components

What is the main purpose of a pitless adapter?

  1. It carries water through the casing wall below the frost line Correct answer.
  2. It supports the pump motor inside the well screen
  3. It controls the pump's electrical starting circuit
  4. It seals the top of the well casing above ground

Explanation

A pitless adapter makes a watertight connection through the casing wall below the frost line. It supports the drop pipe and pump assembly and lets a technician pull the pump without excavating the discharge line.

Question 7Pump and Water System Components

Why is a torque arrestor installed on a submersible pump?

  1. It increases the discharge head at high flow rates
  2. It keeps the motor windings from overheating
  3. It cushions starting torque on the drop pipe and wires Correct answer.
  4. It centers the pump inside the well screen

Explanation

When a submersible motor starts, the pump assembly can twist against the drop pipe. A torque arrestor grips the casing and cushions that starting torque, protecting the pipe threads and the motor leads.

Question 8Pump and Water System Components

A pump cycles on and off every few seconds while a fixture is open, and the gauge swings rapidly between 30 and 50 psi. The tank feels heavy and no air comes out of the Schrader valve. What is the most likely cause?

  1. The pressure switch differential is set too wide
  2. The motor is running on the wrong supply voltage
  3. The well yield is greater than the pump output
  4. The tank has lost its air charge or bladder Correct answer.

Explanation

A tank that feels heavy and releases no air at the Schrader valve has lost its air charge or bladder. With no air cushion the tank is waterlogged, so pressure rises and falls almost instantly and the pump short-cycles.

Question 9Pump and Water System Components

With every fixture closed, system pressure drops slowly from 60 to 40 psi over several minutes and the pump restarts, although no leaks are visible. Which component is most likely at fault?

  1. A pressure switch with too narrow a differential
  2. A pump impeller worn past its published curve
  3. A pressure tank carrying too much precharge
  4. A leaking check valve allowing water to drain back Correct answer.

Explanation

Pressure that falls slowly with every fixture closed means water is leaving the system somewhere. Since no external leak is visible, the usual cause is a check valve that no longer seals, letting the riser drain back into the well.

Question 10Pump and Water System Components

What does the control box on a three-wire submersible pump contain?

  1. The pitless adapter and the well seal
  2. The pressure switch and the pressure gauge
  3. The check valve and the torque arrestor
  4. The starting capacitor and the start relay Correct answer.

Explanation

A three-wire submersible motor needs a control box above ground to hold the starting capacitor and start relay, along with overload protection. Two-wire motors have those starting components built into the motor housing.

Question 11Pump and Water System Components

What is the purpose of a pressure relief valve installed on a domestic well system tank tee?

  1. To drain sediment from the bottom of the pressure tank during service
  2. To prevent water from flowing backward through the pump when it stops
  3. To admit air into the tank when the pump shuts off
  4. To release water if system pressure exceeds a safe limit Correct answer.

Explanation

A pressure relief valve is a safety device set above the normal pressure switch cut-out point. If the switch fails to open or the tank becomes overpressurized, the valve opens and discharges water to protect the tank, piping, and fittings from bursting.

Question 12Pump and Water System Components

What is the main function of a sanitary well seal at the top of a cased well?

  1. It supports the weight of the submersible pump and drop pipe.
  2. It regulates the pump discharge pressure by restricting flow.
  3. It allows the pump to draw air when the water level drops.
  4. It seals the casing opening to keep surface water and debris out. Correct answer.

Explanation

A well seal closes the top of the casing around the drop pipe, wiring, and any vent piping. This keeps surface runoff, insects, and debris from entering the well and contaminating the water supply.

Question 13Pump and Water System Components

What does the pressure gauge on a well system tank tee indicate?

  1. The water pressure at that point in the system Correct answer.
  2. The water level inside the well
  3. The electrical current drawn by the pump motor
  4. The volume of water stored in the pressure tank

Explanation

A pressure gauge reads the internal water pressure at its connection point, which is usually the tank tee. Installers use this reading to set the pressure switch and tank precharge and to diagnose cycling, pressure loss, or excessive pressure.

Question 14Pump and Water System Components

In a deep-well two-pipe jet pump system, what does the ejector do?

  1. It filters sand and grit before water enters the pump.
  2. It stores water under pressure to reduce pump cycling.
  3. It creates suction with a nozzle and venturi to lift well water. Correct answer.
  4. It shuts off the pump when the well water level falls below the intake.

Explanation

The ejector, also called a jet assembly, contains a nozzle and venturi. Part of the pump discharge is sent down one pipe and forced through the nozzle, creating a low-pressure area that draws well water up the second pipe to the pump.

Question 15Pump and Water System Components

In a bladder-type pressure tank, where is the system water normally contained?

  1. Inside the bladder, with compressed air surrounding it in the tank shell Correct answer.
  2. In a separate vertical standpipe connected to the tank tee
  3. In the tank shell outside the bladder, with air inside the bladder
  4. In the pump drop pipe above the check valve

Explanation

A bladder tank has a flexible bag that holds the water and separates it from the factory air charge. As water enters the bladder, it compresses the air in the tank shell, and that compressed air pushes water out when a fixture opens.

Question 16Pump and Water System Components

What is the function of a cycle stop valve installed on a submersible pump system?

  1. It prevents the pump from starting if the well is dry.
  2. It regulates pump output to hold a steady pressure and reduce short cycling. Correct answer.
  3. It adds air to the pressure tank to maintain precharge.
  4. It shuts the pump off whenever a single faucet is opened.

Explanation

A cycle stop valve throttles the pump discharge to match demand while keeping pressure nearly constant. This keeps the pump running at low flows instead of cycling on and off rapidly, reducing wear on the pump, motor, and pressure switch.

Question 17Pump and Water System Components

Why is a flow sleeve, or cooling shroud, sometimes installed around a submersible pump motor?

  1. To force water to flow past the motor so it stays cool Correct answer.
  2. To make the pump easier to lower into a crooked well
  3. To keep sand and gravel from entering the pump intake
  4. To increase the pump's discharge head at high flow rates

Explanation

A submersible motor relies on water moving past its housing to carry away heat. In a large-diameter well or when the motor is set below the pump intake, a flow sleeve directs water along the motor to maintain adequate cooling.

Question 18Pump and Water System Components

What is the role of the tank tee in a domestic well system?

  1. It provides ports for the tank, switch, gauge, and relief valve. Correct answer.
  2. It reduces the pump discharge pressure to the switch setting.
  3. It automatically mixes air with water to prevent corrosion.
  4. It serves as the well seal at the top of the casing.

Explanation

The tank tee is a fitting that connects the pressure tank to the service line and provides threaded ports for the pressure switch, gauge, drain valve, and relief valve. It centralizes the controls and simplifies installation and service.

Question 19Pump and Water System Components

A two-wire submersible pump motor has built-in thermal overload protection. What does this protection do?

  1. It limits the pump's maximum discharge pressure by bypassing water.
  2. It reverses the motor rotation to clear sand from the impellers.
  3. It disconnects the pump whenever the pressure tank precharge is low.
  4. It opens the circuit when the motor winding gets too hot. Correct answer.

Explanation

Two-wire submersible motors commonly use an internal thermal overload that senses winding temperature. If the motor overheats from low flow, high ambient temperature, or a jammed impeller, the overload opens the circuit and stops the motor until it cools.

Question 20Pump and Water System Components

A shallow-well jet pump loses its prime after the pump stops. Which condition would most directly cause this?

  1. The foot valve leaks and lets water drain back down the suction pipe. Correct answer.
  2. The pump motor is wired for the wrong voltage.
  3. The pressure switch is set too high for the tank precharge.
  4. The pressure relief valve is set below the cut-out pressure.

Explanation

A shallow-well jet pump must keep its suction pipe and pump casing full of water to prime. A leaking foot valve lets that water drain back into the well after shutdown, so the pump loses prime and must be reprimed before it can build pressure again.

Question 21Pump and Water System Components

In a submersible pump installation, what is the purpose of a cable guard?

  1. It seals the cable entry point where the wires pass through the well cap.
  2. It holds the motor cable against the drop pipe to prevent abrasion. Correct answer.
  3. It boosts the voltage supplied to the motor during starting.
  4. It filters debris from water entering the pump intake.

Explanation

A cable guard is a clamp or guide that fastens the motor cable to the drop pipe at intervals. It keeps the cable from rubbing against the casing and carrying its own weight, which can damage insulation.

Question 22Pump and Water System Components

What does the drawdown of a pressure tank describe?

  1. The amount of air lost through the tank bladder each year.
  2. The water volume delivered between pump cut-in and cut-out. Correct answer.
  3. The vertical distance the water level drops in the well when the pump runs.
  4. The maximum pressure the tank can safely contain.

Explanation

Tank drawdown is the usable water volume released as pressure falls from cut-out to cut-in. It depends on tank size, precharge, and pressure settings, and is not the same as the water-level drop in the well.

Question 23Pump and Water System Components

In a system that pumps to a storage tank, what is the function of a float switch?

  1. It removes dissolved gases from the water before it enters the tank.
  2. It starts and stops the pump based on tank water level. Correct answer.
  3. It prevents water from flowing backward through the pump.
  4. It limits the maximum discharge pressure at the tank tee.

Explanation

A float switch senses tank level and opens or closes the pump control circuit. It is used when pumping to a storage tank rather than relying on a pressure switch.

Question 24Pump and Water System Components

Why is a submersible pump usually set several feet above the well bottom?

  1. To keep sediment out of the pump and motor. Correct answer.
  2. To reduce the electrical cable length required.
  3. To allow the check valve to be omitted.
  4. To keep the pump above the frost line.

Explanation

Submersible pumps are usually set several feet above the well bottom. This reduces the chance of pumping sand or sediment and keeps the motor from becoming buried as material accumulates.

Question 25Pump and Water System Components

What is the purpose of a bleeder orifice in a submersible pump system serving a freeze-prone line?

  1. It admits air into the pressure tank to maintain precharge.
  2. It opens to relieve excess pressure above the cut-out setting.
  3. It prevents the pump from starting when the well level is too low.
  4. It drains the drop pipe after shutdown to prevent freezing. Correct answer.

Explanation

A bleeder orifice is a small opening in the drop pipe near the pump. When the pump stops, it lets the pipe drain so standing water cannot freeze and split the line.

Question 26Pump and Water System Components

Why are submersible pump cable splices made with heat-shrink kits rated for immersion?

  1. To keep water out of the splice and prevent insulation failure. Correct answer.
  2. To color-code the motor leads for voltage identification.
  3. To provide a flexible mechanical coupling between drop pipe sections.
  4. To increase the current-carrying capacity of the cable.

Explanation

Submersible cable splices must be waterproof because the connection sits in the well. A heat-shrink splice kit seals each conductor and the outer jacket so water cannot reach the strands.

Question 27Pump and Water System Components

A bladder-type pressure tank has a ruptured bladder. What is the most likely result?

  1. The pressure relief valve opens continuously.
  2. The pump loses prime and stops moving water.
  3. The pressure switch fails to open at cut-out.
  4. The tank becomes waterlogged and the pump short-cycles. Correct answer.

Explanation

The bladder separates air from water. If it ruptures, water fills the air chamber, leaving little cushion, so pressure swings quickly and the pump short-cycles.

Question 28Pump and Water System Components

What does the range adjustment nut on a pressure switch change?

  1. The maximum flow rate through the tank tee.
  2. Both cut-in and cut-out pressure settings together. Correct answer.
  3. The difference between cut-in and cut-out only.
  4. The air precharge in the pressure tank.

Explanation

The range nut moves both set points up or down together. The differential nut separately changes the gap between cut-in and cut-out.

Question 29Pump and Water System Components

A three-wire submersible pump has a start relay that sticks closed after the motor reaches speed. What is the likely result?

  1. The pump loses prime and stops delivering water.
  2. The motor runs at half speed but stays cool.
  3. The pressure switch opens immediately.
  4. The start winding stays energized and may overheat. Correct answer.

Explanation

The start relay removes the start winding from the circuit after the motor accelerates. If its contacts stick closed, the start winding remains energized and can overheat or burn out.

Question 30Pump and Water System Components

In a two-pipe deep-well jet pump system, what happens if the drive pipe is undersized?

  1. The ejector produces more suction because velocity increases.
  2. The pressure tank precharge rises above its setting.
  3. The pump runs cooler because less water moves through it.
  4. Higher friction loss reduces the pressure at the ejector nozzle. Correct answer.

Explanation

An undersized drive pipe increases friction loss in the high-pressure line feeding the ejector. Less pressure reaches the nozzle, so the jet produces weaker suction and lower pump performance.

Question 31Pump and Water System Components

A pitless adapter is installed on a cased well. What does it allow?

  1. The pump motor to be cooled by well water
  2. Water to pass through the casing wall below the frost line Correct answer.
  3. Sand and sediment to settle out before entering the pump
  4. The well casing to be vented to the atmosphere

Explanation

A pitless adapter is a fitting that carries the drop pipe through the casing wall below the frost line and makes a removable, watertight connection to the service line. This keeps the well head clear and protects the service line from freezing.

Question 32Pump and Water System Components

Where is a foot valve normally installed in a shallow-well jet pump system?

  1. At the pressure switch connection on the tank tee
  2. At the bottom of the suction pipe in the well Correct answer.
  3. On the discharge side of the pump
  4. Between the pressure tank and the service line

Explanation

A foot valve is a one-way valve placed at the bottom of the suction pipe so water cannot drain back down the pipe when the pump stops. Keeping the suction line full of water allows the jet pump to prime reliably.

Question 33Pump and Water System Components

What is the purpose of a torque arrestor on a submersible pump installation?

  1. It protects the motor from lightning surges
  2. It seals the pump discharge to the drop pipe
  3. It centers the pump in the casing
  4. It limits motor twist that can loosen pipe couplings Correct answer.

Explanation

A torque arrestor uses rubber fins that press against the well casing to absorb the reaction torque produced when the motor starts. This reduces twisting of the pump and drop pipe, which helps prevent loosened couplings and cable damage.

Question 34Pump and Water System Components

A bladder pressure tank is paired with a pressure switch set at 30/50 psi. The tank precharge should normally be set to about:

  1. 28 psi Correct answer.
  2. 40 psi
  3. 20 psi
  4. 50 psi

Explanation

The standard rule is to set the tank precharge about 2 psi below the pressure switch cut-in setting. With a 30 psi cut-in, that gives a precharge of approximately 28 psi, which allows a small amount of water to remain in the tank at cut-in and prevents short cycling.

Question 35Pump and Water System Components

A check valve is installed on the discharge of a submersible pump. What is its main function?

  1. To stop water from draining back when the pump stops Correct answer.
  2. To admit air into the drop pipe to prevent freezing
  3. To limit the maximum pressure in the tank
  4. To measure the flow rate leaving the well

Explanation

The check valve holds the water column in the drop pipe after the pump shuts off, preventing backflow through the pump. This protects the pump from repeated backspin and startup loading and helps maintain system pressure.

Question 36Pump and Water System Components

What does an air volume control do on a galvanized (non-bladder) pressure tank?

  1. It maintains an air cushion above the water Correct answer.
  2. It filters sediment from the incoming well water
  3. It drains water from the bottom of the tank
  4. It boosts the pump pressure to the cut-out setting

Explanation

A galvanized tank has no bladder, so its air cushion gradually dissolves into the water and is carried away. The air volume control adds air as needed to maintain that cushion, which keeps the tank from becoming waterlogged and cycling the pump.

Question 37Pump and Water System Components

A pump protection control shuts off a submersible pump when the well water level drops below the intake. What is this device called?

  1. A low-water cutoff Correct answer.
  2. A pressure reducing valve
  3. A bypass relief valve
  4. A snifter valve

Explanation

A low-water cutoff senses that the water level has fallen below a safe point and interrupts power to the pump. Running a submersible pump dry can overheat and damage the motor, so this control protects the equipment and the well.

Question 38Pump and Water System Components

How does a variable-frequency drive maintain constant water pressure in a well system?

  1. By changing the pump motor speed in response to pressure Correct answer.
  2. By changing the pressure switch cut-in point
  3. By adding air to the pressure tank as flow changes
  4. By opening a bypass valve when pressure rises

Explanation

A variable-frequency drive uses a pressure sensor and electronics to change the frequency and voltage supplied to the motor, which varies pump speed. As demand changes, the controller speeds the pump up or slows it down so the system pressure stays near the set point.

Question 39Pump and Water System Components

A pump must lift water 60 ft, maintain 40 psi at the tank, and overcome 20 ft of friction loss. The water level draws down 10 ft while pumping. What total dynamic head must the pump produce? (1 psi is about 2.31 ft)

  1. About 90 ft
  2. About 80 ft
  3. About 182 ft Correct answer.
  4. About 272 ft

Explanation

Convert the pressure to head: 40 psi times 2.31 equals about 92.4 ft. Add the 60 ft lift, the 10 ft drawdown, and the 20 ft friction loss to get approximately 182 ft of total dynamic head.

Question 40Pump and Water System Components

A 240 V submersible pump circuit measures 242 V at the control box and 226 V at the motor. What is the most likely cause?

  1. The pump is running in a dry well
  2. The pressure switch is set too high
  3. The cable conductors are too small for the run Correct answer.
  4. The check valve is stuck open

Explanation

The 16 V difference is about 6.7 percent of 240 V, which exceeds the usual allowable voltage drop for a pump circuit. Undersized conductors over a long run are the most likely cause, and the cable size should be increased to bring motor voltage within the motor nameplate tolerance.

Question 41Hydraulics, Sizing, and System Design

A pressure gauge reads 40 psi at the base of a vertical pipe filled with water. What is the equivalent head in feet? (Use 2.31 ft per psi.)

  1. 40.0 ft
  2. 17.3 ft
  3. 92.4 ft Correct answer.
  4. 231 ft

Explanation

Head in feet equals pressure in psi multiplied by 2.31 for water. Therefore 40 psi × 2.31 ft/psi = 92.4 ft. This conversion lets an installer express pressure switch settings as vertical lift in the system.

Question 42Hydraulics, Sizing, and System Design

A bladder pressure tank is used with a 30/50 psi pressure switch. Where should the air precharge be set?

  1. 18 psi
  2. 28 psi Correct answer.
  3. 50 psi
  4. 30 psi

Explanation

The tank precharge is normally set about 2 psi below the pump cut-in pressure. With a 30 psi cut-in, that gives 28 psi and provides a cushion that helps prevent pressure switch chatter. A precharge at or above cut-in can interfere with normal tank drawdown and pump cycling.

Question 43Hydraulics, Sizing, and System Design

What is the primary purpose of installing a check valve at the discharge of a submersible pump?

  1. To increase the pumping rate at deep settings
  2. To regulate the pump discharge pressure
  3. To measure the static water level in the well
  4. To block backflow and protect the pump Correct answer.

Explanation

A check valve allows flow out of the pump but blocks reverse flow when the pump stops. This holds pressure in the drop pipe, prevents backspin, and reduces water hammer and contamination risk. It does not regulate pressure or measure water level.

Question 44Hydraulics, Sizing, and System Design

A 180 ft length of drop pipe has a friction loss of 6 ft per 100 ft at the design flow rate. What is the friction loss for this pipe length alone?

  1. 10.8 ft Correct answer.
  2. 3.3 ft
  3. 18.0 ft
  4. 6.0 ft

Explanation

Multiply the loss per 100 ft by the actual length divided by 100: 6 ft × 1.8 = 10.8 ft. This friction loss is added to lift and pressure head when calculating total dynamic head. Fittings and valves would add additional losses if included.

Question 45Hydraulics, Sizing, and System Design

A pump is delivering 12 gpm when the pressure tank reaches a 50 psi cut-out setting. If the pressure switch is changed so the pump runs until 60 psi before shutting off, what happens to the flow just before shutoff, assuming the same pump curve?

  1. Exactly 12 gpm, because the pump curve is unchanged.
  2. Lower flow, because higher pressure raises system head. Correct answer.
  3. Zero flow at 60 psi, regardless of pump curve.
  4. Greater flow, because the pump runs longer.

Explanation

On a given pump curve, flow decreases as discharge head increases. Raising the cut-out pressure raises the required pressure head, so the operating point moves toward lower flow. The pump does not deliver more flow merely because it runs longer.

Question 46Hydraulics, Sizing, and System Design

At the same flow rate, replacing a 1 in. drop pipe with a 1-1/4 in. drop pipe will generally cause which change?

  1. No change in friction loss because flow is unchanged
  2. Lower friction loss and a lower total dynamic head Correct answer.
  3. Higher static water level in the well
  4. Higher friction loss and a higher total dynamic head

Explanation

A larger pipe diameter reduces velocity and friction loss for the same flow. Lower friction loss reduces total dynamic head, so the pump may operate at a slightly higher flow on its curve. Static water level is a well condition and is not changed by drop pipe size.

Question 47Hydraulics, Sizing, and System Design

A well yields 5 gpm reliably during dry weather. Which pump capacity is best for a system that pumps directly to a pressure tank without additional storage?

  1. 1 gpm, to guarantee the well never drops
  2. 5 gpm or less, matched to the well yield Correct answer.
  3. 10 gpm, to fill the tank faster
  4. 20 gpm, to shorten run time

Explanation

A pump should not be sized to exceed the sustainable well yield, or it may draw the water level down to the pump intake and run dry. Matching the pump to about 5 gpm or less protects the well and pump; additional storage can allow a larger pump if desired. Faster fill rate is not a reason to exceed yield.

Question 48Hydraulics, Sizing, and System Design

A pump is set so the pumping water level is 75 ft below ground. The pressure switch cut-out is 60 psi, friction loss is 20 ft, and the discharge outlet is 5 ft above ground. What is the total dynamic head at the cut-out condition? (Use 2.31 ft per psi.)

  1. 238.6 ft Correct answer.
  2. 300.0 ft
  3. 100.0 ft
  4. 158.6 ft

Explanation

Convert pressure to head: 60 psi × 2.31 = 138.6 ft. Add lift from pumping level to outlet (75 + 5 = 80 ft), friction loss (20 ft), and pressure head (138.6 ft): 80 + 20 + 138.6 = 238.6 ft. Total dynamic head includes all these components, not just the well depth.

Question 49Hydraulics, Sizing, and System Design

A pump with a 30/50 psi switch and a 20-gallon bladder tank cycles every few seconds even when no fixtures are open. The tank precharge is 28 psi and the tank is not waterlogged. Which cause is most likely?

  1. A pump that produces too much pressure at shutoff
  2. A leaking check valve that lets water drain back Correct answer.
  3. A pressure switch set with too wide a differential
  4. A tank that is larger than the pump can fill

Explanation

Rapid cycling with no demand means pressure is being lost and regained quickly. A leaking check valve lets water drain back into the well, so pressure falls to cut-in almost immediately after shutoff and the pump restarts. A wide switch differential would lengthen, not shorten, the cycle.

Question 50Hydraulics, Sizing, and System Design

For a shallow well with a water level 20 ft below the pump, which pump type is normally suitable?

  1. A positive displacement pump with no suction limit
  2. A shallow-well jet pump Correct answer.
  3. A deep-well submersible pump only
  4. A turbine pump set below the water level

Explanation

A shallow-well jet pump can lift water from depths of roughly 25 ft or less, depending on altitude and friction losses. At a 20 ft water level, it is within the normal suction-lift range. Deep-well submersible or turbine pumps are used when the water level is deeper.