Pumps for Private Water Supply Systems 060401b Flashcards
Name 4 reasons why you would use the centrifugal pump for private water supply?
- the pumps are relatively east to produce
- they can be small and lightweight
- can be adapted to many convenient forms of drive
- they are generally very good at moving fluid
What is the maximum theoretical lift of a centrifugal pump?
34 feet
What is the maximum practical lift of a centrifugal pump at sea level?
25 feet
The practical lift of a suction pump must be reduced by how much for every 1000 feet of elevation difference?
1 foot for every 1000 feet of elevation gain
What is variable displacement?
When a pump is asked to do more work in the form of increased height and fluid lift or increased output pressure output from the pump, the amount of water coming from the centrifugal pump reduces
As discharge pressure or discharge height increases, a pump cannot move as much water as it would at lower discharge pressure or height due to increased slippage. The pump will still try to move the fluid, but the fluid cannot move away from the pump. What will this cause to occur?
Pump cavitation
What 2 factors create the pressure output of a pump?
- the height it can move the fluid
- the relative density of the fluid
What can be done when running a line from the wellhead to the pump inlet to allow better air elimination from suction line when priming?
Should grade upward from wellhead to pump inlet
What function in the impeller allows gasses to escape the water?
Reduction in pressure at the eye of the impeller
In some instances the water from a well may have dissolved gases that come out of it when the pressure is reduced by a centrifugal pump placed in it. What must be done to account for these gasses?
A pressure tank that does not have air/water separation in it may need to be used to allow venting of gases from the supply water
What is the usual method of controlling a private water supply pump?
Pressure switch
What are the 2 acceptable cut in/cut out pressures for private water supply pressure switches?
20-40 psi or 30-50 psi
To prevent undue wear and tear on a pump motor, the run cycle of a centrifugal pump is recommended to be how long?
2 minutes
A centrifugal pump on private water supply should not cycle more than how many times per hour?
25
What are the 2 different types of reciprocating piston pumps?
- Horizontal reciprocating pump
- Deep-well working head pumps
Reciprocating pumps must be protected by what?
Pressure relief
The pressure relief valve being used to protect a system using a reciprocating pump is usually set to relieve at how many psi over the cut-out setting?
15-20 psi
Reciprocating pumps are often used for what application?
- Low production wells that do not have the water volume or capacity to supply the owners requirements directly from the well
- wells from an aquifer that allows sand to enter the well with water from the aquifer. A centrifugal pump can quickly wear if sand is pumped with the water
Diaphragm pumps are often used for what application?
- Moving corrosive material
- often hand operated and sometimes used as fuel transfer pumps or in applications where power is unavailable
What is the most common use for a bladder pump?
Used where corrosive or sensitive materials must be pumped. Often used for pumping rather than developing pressure
Rotary pumps are similar to centrifugal pumps because the rotary motion of a power source makes the pump turn in a circular manner, but what sets these pumps apart from centrifugal pumps?
Rotary pumps are positive displacement pumps and centrifugal pumps are variable displacement pumps
What application would require the use of a gear style rotary pump?
Wet sprinkler systems piped for fire suppression where a pump with low flow is desired but high pressure capability is needed
What application would require the use of a helical rotor pump?
Could be used as a suction pump for private water systems, but is seldom encountered in service unless heavy fluids like sludge or slurry applications are in place
What application would require the use of a regenerative turbine pump?
Often used for municipal water applications or boosted water pressure systems in high buildings
What application would require the use of a peristaltic pump?
Extensively used in the health profession for kidney dialysis
Jet pumps are centrifugal pumps that have been adapted by incorporating what 2 things into the inlet of the impeller housing?
A nozzle and Venturi
How do you size the suction pipe in a 2 pipe jet pump application?
The suction pipe is usually one size larger than the pump driveline
A typical impeller section for a submersible pump will generally increase water pressure available from the impeller by how much?
9 psi per stage
You should avoid using this to secure wiring in a submersible well pump application
Electrical tape
Use zip ties
The delivery capacity of a pump must be…
Equal to or less than the amount of water available to the well from the aquifer
Centrifugal pumps used as suction pumps are limited to a practical suction lift of how many feet?
15 to 20 feet
Centrifugal jet pumps used for suction are limited to how many feet of lift?
20 to 25 feet
Centrifugal jet pumps used for deeps wells is usually limited to depths of approximately how many feet?
180 feet
A submersible pump may be capable of developing pressure greater than the components of the system can handle and may require the addition of a pressure relief set at how many psi above cut out pressure?
10 psi
A clear water sump pump often has what kind of impeller?
Closed impeller
A sump pump used for subsurface drainage may only need a pump with what kind of impeller?
Semi-open
A sump pump used for a dewatering application around construction sites may require a pump with what kind of impeller ?
Open impeller to move relatively large solids through the pump
Residential pump sizing is based on what?
Seven minute peak demand period that may occur 2-3 times a day
Agricultural pump sizing is based on what?
Two hour peak demand period that may occur twice a day
To properly size the drop pipe and supply pipe to a house requires detailed calculation of what factors?
- pipe lengths
- number of fittings
- flow rate of system
- elevation difference
- desired pressure
Most residential submersible pumps are installed with what size of drop pipe and supply line to the house?
1” and in rare instances 11/4”
When is a well considered a deep well?
When the wells pumping level is greater than 24 feet
How may drawdown in a well effect an aquifer?
Drawdown can allow the aquifer to start releasing sand
What type of piston pump can be offset from the top of a well?
Shallow well piston
When a shut off valve is placed on a tank tee in a residential application, which side of the tank tee should it be placed on?
Outlet of tank tee
