Positive Displacement: The Peristaltic

Pump

Prepared By:-Stephanie Arbelovsky

-Andrea Hektor-Christina

HynesDecember 17,

2004

Project Goals:• Create a constant flow

device for a point-of-use water supply system in a developing community.

• Develop a system that was sustainable, affordable, and readily available.

• Experiment with various drive mechanisms, such as a clock, pendulum, and a weight system.

Concept: Peristaltic Pumps

• Peristalsis – a natural process of involuntary wave-like successive muscular contractions by which food is moved through the digestive tract.

• Operates by batching a certain volume of water and forcing it along a tube.

• A rotor attached to an external circumference compresses and releases a flexible tube with rollers, creating a squeezing action that draws fluid through the tubing.

Peristaltic Pump

• Positive Displacement Pump (PDP)

• 3 Parts– Pump Head– Drive Mechanism– Tubing

Pump Head

• Masterflex® L/S Easy-load

• Worked only with Masterflex® tubing

• Torque required entirely dependent on tubing used

Tubing• Masterflex®

Precision– Nontoxic– 275 degrees to -

75 degrees Fahrenheit

– Longer life

• Flow Rate• Torque

Flow Rate

Size PulsesRotatio

ns VV/

rotationRotatio

n/

      (ml) (ml) day

#18 180 60 238 3.967 5,042

#17 240 80 233 2.913 6,867

#16 480 160 144 0.900 22,222

#14 420 140 41 0.293 68,293

#13 777 259 16 0.062 323,750

Torque

  No. of Torque Torque

Size heads kg-cm oz-in

#18 1 8.6 120

#17 1 8.6 120

#16 1 3.2 45

#14 1 2.9 40

#13 1 1.4 20

Clocks• Two Types:

– Electrical– Mechanical

• Weights• Springs

• Governed By Escapement Mechanism

• Why Not Have Gears Turn Pump Instead of Clock Hands?

Giving it our best shot with

Tinker Toys!

LEGO MAN!

• To Make It Work:– Large gears 175 teeth,

medium gear 35 teeth, small gears 25 teeth

– Pendulum 107.5 cm long, with escapement mechanism on last gear•Period: 2.08 s

– 2 kg weight

Do-It-Yourself Kits

• Woodworker Kit– Templates for gears

• Home Assembly Kits– Can buy pre-cut clock housing– Weight/pendulum sold separately

Advantages• Able to vary flow

based on need– Can be scaled up &

down

• Does not require constant head loss

• Self priming• Prevents backflow• Inside of tube is

only area in contact with fluid– Low risk of

contamination

• Easy & convenient maintenance and cleanup

• Flexible staging options – can be placed after filter

Disadvantages

• Preliminary design is expensive– Rotor, peristaltic

tubing, pendulum, etc.

• Durability concerns if cheaper, thin walled tubing is used

• Availability of materials

• Finding a drive mechanism with enough power to turn the rotor

Recommendations for Further Research:

• Find a more practical pump head

• Use less expensive, flexible tubing

• Experiment with pendulum mechanisms in order to establish steady flow

• Evaluate flow rate compared to size and type of materials used

References and Thank Yous

• "Plant Extracts."  [Online] Available http://www.sciences.com/scidata/edu.html  February 23, 1997.

•  • “How Pendulum Clocks Work” [Online] Available

http://www.howstuffworks.com November 14, 2004.•  • “Technical Info” [Online] Available http://www.masterflex.com December

2, 2004•  • “Technical Info” [Online] Available http://www.barnant.com December 2,

2004•  • White, Frank M. Fluid Mechanics. McGraw-Hill Science/Engineering/Math;

5th edition December 2002.•  • Young, Donald F. ; Munson, Bruce R.; and Okiishi, Theodore H. A Brief

Introduction to Fluid Mechanics, 2nd Edition. John Wiley & Sons. October 2000.

•  • CEE 454 website and class notes Available

http://ceeserver.cee.cornell.edu/mw24/cee454/ • www.clockplans.com• www.murrayclock.com• http://www.ericharshbarger.org/lego/clock.html

(A heart-felt thank you goes out to Lego Man for providing inspiration.