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