Home' Smart Farmer : September 2009 Contents SEPTEMBER, 2009 smartfarmer
BY DAVID EAST
THE most common and
perhaps the most useful
pump used in rural
Australia is the centrifugal
Most water system pumps,
whether they be multi-stage,
shallow or deep-well jet pumps,
submersible or end-suction
centrifugals, are based on the
principle of the centrifugal
Pumps are machines whose
sole purpose in life is to
convert power from a motor,
engine or power take-off and
convert it into a useful
combination of water flow and
This energy conversion takes
place in the 'wet-end' of the
In a basic centrifugal pump,
water is delivered via a suction
connection to the centre of a
rotating impeller that
accelerates it (the water)
outwards at right angles to the
The high-velocity water then
passes through a volute or
diffuser where it is converted to
a pressure head leaving the
pump at a discharge connection
All this energy conversion is
brought about by centrifugal
force, thus the name centrifugal
The major rotating part of a
centrifugal pump is the
impeller and the nature of the
pumped fluid will dictate its
design and shape.
Open and semi-open
impellers are able to handle
fluids containing solids and
fibrous material without
blocking, while closed face
impellers are able to handle
water that contains very little, if
any, solids or fibrous materials.
Closed face impeller pumps
are more efficient and are the
most common type of impeller
used in most water pumping
Single stage (impeller) pumps
are most frequently used
around rural properties in
applications requiring high flow
rather than high pressure such
as general water transfer, tank to
tank transfer and general water
On the other hand, for
applications requiring higher
flow and higher pressure such
as fire fighting, a multi-stage
centrifugal pump should be
These pumps feature several
impellers mounted in a series
on the pump shaft in either
horizontal or vertical
Each impeller pressure boosts
it input from the previous one
thus producing higher heads at
the pump discharge.
Centrifugal pumps offer
several advantages over other
types of water transfer pumps.
Firstly, unlike reciprocating
positive displacement pumps
(piston or diaphragm) they give
a smooth, non-pulsating flow.
They also have no internal
reciprocating parts, such as
valves, and they can tolerate a
short run time against a closed
discharge without damage.
Single stage centrifugal
pumps are simple in design and
construction and are
comparatively easy to service
and repair and they are
hydraulically more efficient and
cheaper to run.
As most centrifugal pumps
used for pumping water feature
closed impellers, any inclusion
of sand, gravel and fibrous
material can quickly block the
impeller and stop the pump
While open impeller
centrifugal pumps can handle a
certain amount of solids, other
types such as diaphragm pumps
are better for handling
frequently dirty or gritty water.
Single stage centrifugal
pumps generally do not have
the pressure generating
capability of jet pumps of equal
power despite their superior
Get onto centrifugal 'power'
PUMP POWER: For quick and efficient water movement, it is hard to go
past the centrifugal pump. Available in sizes from 25mm to more
than 100mm, they can be either petrol or diesel powered.
Pump troubleshooting guide
• Lack of prime -- re-prime
• Excessive suction head -- check
suction size and/or lift
• Excessive delivery head -- check
all valves open and no
• Pump clogged -- check impeller,
all valves open
• Air leaks -- check suction pipes
and pump seals
• Wrong direction of rotation --
• Worn or partially clogged
• Incorrect pipe size -- increase
• Blockage restriction -- check all
inlets/outlets and valves
• Poor suction -- check suction
pipe location and foot valve
• Wrong pump -- is pump correctly
sized for the job?
• Worn impeller
• Wrong rotation
• Speed too low
• Pipe too small
• Excessive delivery head
• Wrong pump
Are you ready for the coming bushfire season?
Living in the Adelaide Hills is a lifestyle choice for many of us, the
benefits of living in a bush setting are what attract many people to
the hills, however the risks of this lifestyle choice can not be ig-
nored, as residents are also vulnerable to the risk of bushfire.
As you live in a high bushfire risk area you can expect several days
a year on which you, your family and your house may be threat-
ened by fire.
Because of the scale and risk of fire, CFS cannot guarantee the
presence of a fire fighting vehicle and crew to protect every home
in a major bushfire, therefore it is extremely important for all prop-
erty owners to undertake the necessary hazard reduction work
around their property in preparation for the Fire Danger Season.
Fuel reduction is one of the most important preparations that you
can undertake and basic requirements include:-
• Slash or mow grass around the home and out buildings.
• Cut back branches overhanging the roof.
• Remove tree limbs, branches, leaf litter, twigs etc from around
• Maintain a 20 metre fuel reduction zone around your home
(greater if on a slope).
• Keep gutters and roofs clear of leaf litter, twigs and debris.
• Remove heaps of bark, heavy mulch, wood and any other
flammable materials that are close to your home or sheds.
• Clearance of Driveway access to accommodate emergency ve-
The onus is on people living in fire risk areas to take responsibility
for their own safety and security, therefore it is important that a
property owner does the necessary hazard reduction work around
Those land owners that ignore the need to prepare their property
for the fire danger season not only endanger their own property,
but also the lives and property of their neighbours and the commu-
As each year passes, more and more properties are not prepared for
the fire season and not only place themselves at risk, but also
neighbours and other members of the community through their ill
It is the responsibility of all landowners, through sound fire preven-
tion practices, to ensure that their land is cleared of fuel loads and
homes are protected in the event of a bushfire and to do the fuel re-
duction works well before the fire danger season beings.
Remember, a well-prepared home is
your best defence.
For help or information:
• More detailed information can be obtained via a series of fact
sheets available on the CFS website www.cfs.org.au.
• If you are unsure of what to
do, where to start or need
an inspection, contact Ade-
laide Hills Council's Fire Pre-
vention Officer on 8408
• You can also contact the
CFS for information about
Community Fire Safe in
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