Pumps Flashcards
What is head Pressure
Head pressure is the pressure measure based on the fluid weight and the force of gravity that pushes down on a fluid
When measuring ich of water column what device do we use?
Inches of water column are measured using a device called a manometer.
Describe how a pump takes up and pushes out water
Pumps use suction to pull water into itself and then the water is moved away from the pump using centrifugal force with a impeller or by displacement
What are public water towers used for
Public water towers provide storage for periods of high demand
What is Geodetic elevation
Geodetic elevation is typically the height of something measured from sea level.
What is suction
Suction is the product of a partial vacuum by the removal of air in order to force fluid into a vacant space (The opposite of PSI)
what is Suction lift or “Suction Head”
Suction lift: the pull of water from the lower elevation of a pump up to the pump (Also known as “Suction Head”)
Describe how a pump works using positive and negative pressures
Water or fluid is pulled into the pump by the pump creating a negative pressure and then sent away in the form of a positive pressure
Why do we use mercury gauges?
Mercury is more dence then water, so we can use a smaller quantity in a manometer and then just convert it to inches of water
How much more dense is mercury then water?
Mercury is 13.6 times more dense than water, this makes it more practical to use for measuring suction head.
Where would a mercury gauge be installed in relation to a pump
it would be installed up stream from a pump, as it measures the suction lift of the pump
What is atmospheric preassure?
ATMpsi is 14.7 psi at sea level and decresses the higher you go up
what is a vacuum
any pressure less then 14.7 psi
What is another name for atmospheric pressure and what divise can you use to measure it?
Atmospheric pressure can also be called Barometric Pressure and is measured using a Barometer
What would be the theoretical max lift a suction could achieve by itself?
14.7 divided by 0.433 = 33.95 ft oh head
What is the practical max of a shallow well and at what level is a well considered a deep well?
Shallow well pumps: Max Suction of 25 feet suction lift
Deep well pumps: Greater than 25 feet suction lift
what height is the max feet for a shallow well measured from
25’ from draw down to the pump
What is static water level
what is drawdown water level
Static water level: is when pump is off
Drawdown: height of well water when pump is on
What is a pressure tank used for?
Pressure tank: Stores water under pressure to ensure the pump doesn’t have to turn on as frequently
What is cut in and cut out. what happens at each stage?
Cut in: Pump turns on when pressure is to low
Cut out: Pump turns off when desired pressure is achieve
What is draw down as it pertains to pressure tanks
Draw down volume: the amount of water that leaves a tank between cut out and cut in
what does a pressure switch control, and what is the delta P involved with it.
Pressure switch: is the control that tells the pump to cut in or cut out. This difference is called Delta P and it is equal to 20 PSI as a industry standard
Why do we need a pressure tank?
Without a pressure tank a system once opened will lose pressure rapidly, this results in a pump turning on and off rapidly, with a pressure tank the length of time between cut in and cut out is significantly longer.
When a pump is rapidly turning on it is called Short cycling a pump
what are the different types of pressure tanks?
Galvanized and Hydro pneumatic
what are the different types of Hydro pneumatic tanks?
Diaphragm and bladder types
What do you do when calculating draw down that is different in galvanized tanks
No pre charge on p1, only atmospheric pressure
how much is the pre-charge in a tank in relation to cut in pressure
2 psi less then cut in pressure
How long should a pump run for?
A pump should run for at least 1 minute and ideally it should run for 2 minutes
What is it called when water fills a pressure tank
When a pump is running every time a fixture is turned on it probably means the tank has no air in it. This mean it is waterlogged
can a tank be replaced once its been water logged?
nope
for every 1 fixter in a building how many GPM should you have?
1 GPM for every fixture
How do you find total dynamic head?
Add Suction head and discharge head
How do you find Suction head
add Elevation difference (from pump to draw down) with Friction loss (from fittings and pipe)
How do you find Discharge head?
add elevation head (Pump to furthest fixture) with Friction loss (of pipe and fittings) and add Residual pressure (The pressure left at the highest fixture)
where else could you find discharge head?
Discharge head can also be found as the cut out pressure
How does pipe size affect friction loss?
The larger the pipe the less the friction loss
The longer the pipe the more friction loss
what are the 3 classifications of pumps?
Rotary
reciprocating
Centrifugal
Which types of pumps are positive displacement pumps and which ones are not
Positive displacement pumps are Rotary and Reciprocating pump
Non positive displacement pumps are centrifugal pumps
what qualities do Reciprocating pumps have
Max suction of 25’, but can be placed in a well so can act as deep well pumps
Have check valves on either side of them
What type of pump is a diaphragm pump and what are some quality’s it has?
Is a reciprocating pump, used for acid waist Used in situations where the we don’t want the pump to come in contact with the product (food processing)
corrosive or acidic fluids
Viscous fluids (Peanut butter)
Concrete
They are common on planes and cars
What type of pump is a piston pump and what are some quality’s it has?
Is a reciprocating pump
Can be used to move
Fluids
Viscous media
Compressed gas
They are used in compressors, industrial applications hydraulics and are highly efficient
A disadvantage of them would be a pulsating delivery of fluid
What are different types of rotery pumps?
Auger pump
Vane pump
Gear pump
Ina cintrifigal pump what are the roles of the:
Impeller
Voulute
Eye
Vanes
Impeller Rotates which creates a negative in the eye
the vanes carry the water to the volute which converts the velocity into psi
Do centrifigal pumps need to be primed?
yes
what does dead heading a pump damage?
dead heading will damage the pump but not the piping
How much suction can a centrifugal pump pull with out and with a jet adapter
with out: about 15-15 feet
with: 100-120 feet
What is the jet pump line called that goes back into the well
the Drive line
what is the fitting that the jet line hooks upto in the well called?
the ejector fitting
what 2 components are in a ejector fitting that create the pressure washer affect
the venture and the nozzle
what minimum psi must be achieved for the drive line?
20 psi minimum
what is cavitation and how does it happen?
Cavitation happens when air bubbles are created when water turns to vapor this happens when:
Not enough suction head in the pump
Too small of a suction line (must not me smaller then one size from the pumps original size)
Throttling a valve on the suction side
Leak in pipe or fittings on the succession side
what does cavitation sound line?
Usually sounds like gravel in the pipe or popcorn popping
what are the three impeller type and where might each be used?
Impeller types:
Open: Solids and sewage
Semi-open: Sump pumps
Enclosed: Jet pumps
in a submersible pump what does each stage consist of?
Each section is called stage and it consists of an impeller, a cup, diffuser and a wear plate
what is a diffuser?
A diffuser does the same job as a volute (Converts velocity into psi)
what is used on a submersible pump to stop it from hitting the well casing when it is started?
Utilizes a torque arrestor on the lower end of the suction line
what happens to psi and GPM in a Series and parallel multi pump configurations
Series and parallel multi pump configurations
Series: PSI increases, GPM stays the same
Parallel: GPM increases, PSI stays the same
what kind of pumps require a pressure relief valve?
Piston pumps require a pressure relief valve
