Hydraulics Flashcards
Hydraulics - the study & ______of
______. Both in _____and at _____
Hydraulics - the study & behaviour of
water. Both in motion and at rest
How are the following measured
- Pressure =
- Velocity =
- Flow =
- Pressure = force (newtons) / area (m²)
- Velocity = speed of water (km/h or m/s)
- Flow = litres / minute (lpm or l/min)
“_____applied to a confined ____at any point is ______
undiminished throughout the fluid in all ____and acts upon
every part of the _____vessel at ____angles to its interior
surfaces and ____upon equal areas
“pressure applied to a confined fluid at any point is **transmitted **
undiminished throughout the fluid in all directions and acts upon
every part of the confining vessel at right angles to its interior
surfaces and equally upon equal areas
6 principle characteristics of pressure in liquids
1. Pressure is _______ to any ______on which it acts.
2. Pressure at any ____of a ___at ____is the same _____in
all _______.
3. Pressure applied from ____to a fluid contained in a _____
is transmitted ____in all directions.
4. _____pressure of a fluid in an ______vessel is ________
to its ______.
5. The ______pressure of a fluid in an ______vessel is
_______to the _____of the fluid.
6. The downward pressure of a fluid on the _____of a vessel is
_________of the _______of that vessel.
6 principle characteristics of pressure in liquids
1. Pressure is perpendicular to any surface on which it acts.
2. Pressure at any point of a fluid at rest is the same intensity in
all directions.
3. Pressure applied from outside to a fluid contained in a vessel
is transmitted equally in all directions.
4. Downward pressure of a fluid in an open vessel is **proportional **
to its depth.
5. The downward pressure of a fluid in an open vessel is
proportional to the density of the fluid.
6. The downward pressure of a fluid on the bottom of a vessel is
independent of the shape of that vessel.
Which law is this?
- Pressure is perpendicular to any surface
on which it acts.
Which law is this
- Pressure at any point of a fluid at rest is of
the same intensity in all directions.
Which law is this?
- Pressure applied from outside to a fluid
contained in a vessel is transmitted equally
in all directions.
Which law is this?
- Downward pressure of a fluid in an open
vessel is proportional to its depth.
Which law is this?
- The downward pressure in an open vessel
is proportional to the density of the fluid.
Which law is this?
- The downward pressure of a fluid on the
bottom of a vessel is independent of the shape
of that vessel.
Characteristics of Pressure
• ___sides
• Position of ____
• Pressure on all ____due to the ____of
the water – _____to those sides
as indicated by the arrows
Characteristics of Pressure
• Flat sides
• Position of rest
• Pressure on all sides due to the weight of
the water – perpendicular to those sides
as indicated by the arrows
Characteristics of Pressure
• ____or hose
• Insert gauges
• Valve or branch ____
• Water at ____
• Gauges register ____readings
showing the ____pressure at any ____
Characteristics of Pressure
• Pipe or hose
• Insert gauges
• Valve or branch closed
• Water at rest
• Gauges register identical readings
showing the same pressure at any point
Characteristics of Pressure
• Pressure at the ____is exactly the ____
in the three vessels, providing that the
____of the liquid or ____is the ____in
each case
Characteristics of Pressure
• Pressure at the base is exactly the same
in the three vessels, providing that the
depth of the liquid or head is the same in
each case
Water - Characteristics
• At normal atmospheric pressure (___kPa)
– Freezing point – ____
– Boiling point – ____
– ____ ≈ 1kg
– 1 m3 = ____ litres
• Virtually _____
• ______of ______any change in vessel
shape
• Relatively high _____ ______
Water - Characteristics
• At normal atmospheric pressure (101 kPa)
– Freezing point – 0o C
– Boiling point – 100o C
– 1 litre ≈ 1kg
– 1 m3 = 1000 litres
• Virtually incompressible
• Incapable of resisting any change in vessel
shape
• Relatively high surface tension
Water - Characteristics
• Water in it’s various forms (salt, fresh, dirty,
drinking) has varying _______.
Water - Characteristics
• Water in it’s various forms (salt, fresh, dirty,
drinking) has varying densities.
Atmospheric Pressure
• Atmospheric pressure is the pressure
_____against a _____by the weight of
_____above (Earth’s atmosphere)
• Atmospheric pressure (at mean sea level) = ______kPa
Atmospheric Pressure
• Atmospheric pressure is the pressure
exerted against a surface by the weight of
air above (Earth’s atmosphere)
• Atmospheric pressure (at mean sea level) = 101.3 kPa
Practically, 10m lift is not ____, due to:
• ____
•____ ____
•_______ ________> leaks, seals
Practically, 10m lift is not achievable, due to:
• Altitude
•Friction loss
•Equipment limitations > leaks, seals
To _____water through hose or pipe, work
has to be performed to _____ _____
which is caused by water particles _____
against each other and the _____surface of
the hose or pipe.
_____to carry out this work is obtained from
the difference in _____, or _____, existing
between the two ends of the hose or pipe.
To propel water through hose or pipe, work
has to be performed to **overcome friction **
which is caused by water particles **rubbing **
against each other and the interior surface of
the hose or pipe.
Energy to carry out this work is obtained from
the difference in pressure, or head, existing
between the two ends of the hose or pipe.
5 Friction Loss Laws
- Length
- Diameter
- Velocity
- Roughness
- Pressure
Length
Friction loss varies directly with the length of the pipe.
____the length - _____the friction loss
Length
Friction loss varies directly with the length of the pipe.
Double the length - double the friction loss
Diameter
For the same ____, friction loss __________ directly
with the _______in diameter.
______diameter –___friction loss –______flow
Diameter
For the same velocity, friction loss decreases directly
with the increase in diameter.
Double diameter –1/2 friction loss –Quadruple flow
Diameter
- Diameter _____
- Surface Area _____
- Flow ______
- Friction Loss ______
Diameter
- Diameter doubled
- Surface Area doubled
- Flow **quadrupled **
- Friction Loss **halved **
Diameter
To _____friction loss,
always use the ______diameter hose
or pipe that is _______.
Diameter
To minimise friction loss,
always use the largest diameter hose
or pipe that is practical.
Velocity
Friction loss increases directly as the **square **of the **velocity.
Halve **velocity -1/4 friction loss
Velocity
Friction loss increases directly as the square of the velocity.
Halve velocity -1/4 friction loss
Roughness
Friction loss ____with the ___ of the internal surface
- Friction factor = .005 for _____ _____hose
- Friction factor = .010 for _____hose
• Friction Factor is a measure of the _____of the inside of the pipe or hose
(________of friction)
Roughness
Friction loss increases with the roughness of the **internal **surface
- Friction factor = .005 for rubber lined hose
- Friction factor = .010 for percolating hose
• Friction Factor is a measure of the roughness of the inside of the pipe or hose
(co-efficient of friction)
Pressure
Friction loss, for all practical purposes, is ________of pressure
Pressure
Friction loss, for all practical purposes, is **independent **of pressure
Loss of Pressure Due to Friction
Calculation:
Formula > __________
Where:
– Pf = pressure loss due to friction (kPa)
– f = friction factor (fixed co-efficient 0.005 for rubber lined hose)
– l = length of pipe (metres)
– v = velocity (metres / second)
– d = diameter (millimetres)
Loss of Pressure Due to Friction
Calculation:
Formula > Pf = 2000flv2/d
Where:
– Pf = pressure loss due to friction (kPa)
– f = friction factor (fixed co-efficient 0.005 for rubber lined hose)
– l = length of pipe (metres)
– v = velocity (metres / second)
– d = diameter (millimetres)
Practical Considerations
to Reduce Friction Loss
- ____the ____hose lines
- Use the ____diameter hose available
- Reduce the ____between:
- ____on the fire-ground
- the pump and ____
- Use the best ____ _____ hose available
Practical Considerations
to Reduce Friction Loss
- Twin the inlet hose lines
- Use the largest diameter hose available
- Reduce the distance between:
- pumps on the fire-ground
- the pump and branch
- Use the best smooth bore hose available
Pressure .v. Kinetic Energy
_____energy is stored in the form of
_____ – water is ______.
When the water has _____this potential
energy is _______to ______energy –
movement of water.
A ______of these two energy forms exist at
various times through pumping & water supply
and _______from one form to the other.
Pressure .v. Kinetic Energy
Potential energy is stored in the form of
pressure – water is stationary.
When the water has velocity this potential
energy is converted to kinetic energy –
movement of water.
A balance of these two energy forms exist at
various times through pumping & water supply
and transfers from one form to the other.
Velocity is ______by _______the diameter
of the hole the water must pass through.
Velocity is increased by reducing the diameter
of the hole the water must pass through.
Branches & Velocity
- Water in a hose must _____up in order to negotiate a _____in diameter.
- This narrowing transfers _____energy (pressure) to _____energy
- principle behind nozzles and hose streams.
The _____the opening,
the _____the amount of _____energy transferred.
Branches & Velocity
- Water in a hose must speed up in order to negotiate a reduction in diameter.
- This narrowing transfers potential energy (pressure) to kinetic energy
- principle behind nozzles and hose streams.
The narrower the opening,
the greater the amount of kinetic energy transferred.
Imperial Gallon = ___ litres
• 1 US Gallon = ___ litres
• kPa = Psi ___
• Psi = kPa ____
Imperial Gallon = 4.5 litres
• 1 US Gallon = 3.8 litres
• kPa = Psi x 7
• Psi = kPa / 7
Jet Reaction
• When water is _____from a branch, a
reaction _____& _____to the force of the _____is created.
• This is the _____energy being _____.
• Branch _____in _____direction of flow
• Branch person must _______jet reaction
Jet Reaction
• When water is projected from a branch, a
reaction equal & opposite to the force of the jet is created.
• This is the kinetic energy being discharged.
• Branch recoils in opposite direction of flow
• Branch person must overcome jet reaction
• Considerations to reduce jet reaction
– On select-o-matic branches, select _____lpm
– _____automatic branches
– Change branch _____used
– Adjust _____ _____used
– ______pump pressure if possible
• Considerations to reduce jet reaction
– On select-o-matic branches, select lower lpm
– Gate automatic branches
– Change branch type used
– Adjust discharge pattern used
– Reduce pump pressure if possible
Water Hammer
• It is necessary to ____close hydrants,
shut-off branches and other valves in
order to _____ water _____which may
burst hose and damage ______, pumps,
tanks and water mains
Water Hammer
• It is necessary to slowly close hydrants,
shut-off branches and other valves in
order to avoid water hammer which may
burst hose and damage couplings, pumps,
tanks and water mains
Effective Hydraulics
Requires the correct selection and use of:
- Water source
- Pumps
- Hoses
- Branches
Water Hammer
• When a ____object (water) ____, the ____
required to ____the object ____on the ____
taken.
– The shorter the ___, the ____the _______exerted
Water Hammer
• When a moving object (water) stops, the force
required to stop the object depends on the time
taken.
– The shorter the time, the greater the force exerted
Water Hammer - Damage
• Damage to equipment from large _____ involved
• Shutting branch ______
– Hose flexible can _____some energy but not
all. Weak spot in hose will result in _____.
– Also can damage ______ and _____.
• Rapid closure of pump ____or ______
itself
– Can cause water main to _____
– Damage most likely when _____diameter
main with ________flow has been utilised
Water Hammer - Damage
• Damage to equipment from large forces involved
• Shutting branch rapidly
– Hose flexible can absorb some energy but not
all. Weak spot in hose will result in burst.
– Also can damage couplings and pumps.
• Rapid closure of pump controls or **hydrant **
itself
– Can cause water main to fracture
– Damage most likely when small diameter
main with high flow has been utilised
