Transcript living with the lab - Louisiana Tech University

living with the lab
pump performance testing
© 2011 LWTL Faculty Team
living with the lab
DISCLAIMER
The content of this presentation is for informational purposes only and is intended only for students
attending Louisiana Tech University.
The author of this information does not make any claims as to the validity or accuracy of the information
or methods presented.
The procedures demonstrated here are potentially dangerous and could result in injury or damage.
Louisiana Tech University and the State of Louisiana, their officers, employees, agents or volunteers, are
not liable or responsible for any injuries, illness, damage or losses which may result from your using the
materials or ideas, or from your performing the experiments or procedures depicted in this presentation.
If you do not agree, then do not view this content.
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living with the lab
switch for DC
power to pump
pump testing system
digital scale to weigh water
water collection column
wiring to allow connection
of multimeters
water collection bucket
12VDC power supply
container to prevent
water leakage
terminals for
pump power
tubing with valve to
connect pump to bucket
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flip the switch to power pump
very briefly just to see if it turns
connect pump just to
see if it will run
connect black leads together
connect red leads together
don’t run pump dry
connect lower
leads to pump
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what if your pump doesn’t run????
no
can you hear or feel
the pump try to run?
you probably aren’t getting any
power to the motor
•
is the power supply plugged in?
•
check your alligator clip connections
•
is the switch on?
•
if these things fail, then use your
multimeter to see if you have power
at the motor leads when the switch is
turned on
yes
your shaft or impeller is stuck and can’t freely rotate
•
look through the clear faceplate to see if you can see the
problem
•
your impeller may be touching the face plate
o unscrew the faceplate screws some . . . all you
need to do is to slightly compress the o-ring to
prevent leaking out of the front
o get an oversized o-ring from instructor if needed
o sand impeller so it is flush with the top of the
pump body to prevent contact
•
the bushing may be squeezing the motor shaft too tightly
→ ream out the bushing with a #42 bit
•
the barbed fitting may be contacting the impeller → try
unscrewing the fitting a few turns
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fill your bucket to the correct level
fill water to the bottom of the tape measure
7 inches
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hook the pump up to the water supply
open valve until water flows freely
through pump . . . this “primes” the pump
outlet
(hooked to long tube)
inlet
(from water bucket)
the pump should ALWAYS stay below the water level in the bucket
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living with the lab
turn the pump on and see what happens
1. if pump doesn’t pump at least one foot, then . . .
• make sure water runs freely through pump when it is off (is it primed?)
• turn outlet upward and tap pump against water bucket to allow bubbles
to float out
• try reversing the polarity of the motor to see if that helps
• if none of these things work, you likely have an air leak
o
o
o
most air leaks are at the faceplate o-ring (keep uniform gap between pump body and
faceplate)
it is also possible that you have an air leak at the bronze bushing → the small o-ring
may have been pushed out
can also have an air leak around a barbed fitting . . . did you use Teflon tape?
2. see how high the pump can pump
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living with the lab
pump testing
•
•
•
•
see how high your pump can pump water
measure electrical current and voltage as well as the mass of water collected at eight
or more heights (or pump heads) up to a maximum of 72 inches
generate a plot of pump head versus flow rate
generate a plot of pump efficiency versus pump head
m = mass of water collected
h = head
head or height that
water is pumped
(in)
electrical current
needed to power pump
(A)
voltage across
pump leads
(V)
length of time that
water is collected
(s)
height 1
20
height 2
20
… height 8 (or more)
20
mass of water collected
over 20 seconds
(g)
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current and voltage measurement
voltage is measured between
the + and – power leads
current is measured by “breaking
a lead” and letting the current
pass through the multimeter
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collect water at different heights for 20 seconds . . .
and weight the water
let water run back
down pipe between
measurement
head or height that
water is pumped
(in)
electrical current
needed to power pump
(A)
voltage across
pump leads
(V)
length of time that
water is collected
(s)
height 1
20
height 2
20
… height 8 (or more)
20
mass of water collected
over 20 seconds
(g)
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remember to zero the digital balance to account
for container weight
the displayed weight is the
actual weight of the water
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living with the lab
SAFETY
• Keep water away from all electrical equipment except the pump, and do
your best to keep the pump motor dry.
• Don’t handle the wall adapter or other power supply with wet hands or
wet feet (or when in contact with water).
• Wipe up any water that leaks onto the floor.
• Report any problems encountered to the help desk or to your instructor.
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cleanup
• empty bucket and catch pan back in sink
• mop up any water leaked or spilled on the floor
• put the station back in its original configuration
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individual versus team
Group Assignment: Fabrication and testing of your pump are group assignments.
The pump fabrication was completed in groups of two students, and pump testing is
to be completed by groups of two to four students; two pump fabrication teams
should combine to test the better of the two pumps fabricated. It is common for
four students to share the same raw data from pump testing.
Individual Assignment: The pump project counts as a significant percentage of your
overall grade, and the work that you submit for this grade must be your own. Please
be aware that the pump assignment is not a “regular” homework assignment. You
are allowed to discuss your work with other students, but no direct copying of work
and no sharing of computer files is allowed (such as Excel and Mathcad files); please
type in the raw data collected into Excel yourself. You may share photographs that
you took of your group during fabrication and testing.
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living with the lab
start your analysis . . .
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