Engineering World Health

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Engineering World Health

• Began in Memphis, TN, 2001
• Improves hospital conditions in developing
  countries
• Funds building of medical device prototypes
• Branches to chapters at schools throughout U.S.
• www.ewh.org

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Abstract

• Gas flow meters measure the rate at which a gas
  is flowing. This is important in the medical
  field to measure how fast the patient is
  receiving O2, CO2, or medical grade air. Third
  World countries cannot afford current flow meters
  to use in their health care systems.

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Problem Statement

• Design a gas flow meter with continuous or single
  readout that can be manufactured for less than 2
  when produced in quantities of 500.

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Background and Motivation

• Applicable to engineering
• Essential to Anesthesiologist
• Imperative to saving lives
• Important to economy
• Unable to afford expensive products

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Current Products

• Rotameter
• Venturi
• Turbine
• Ultrasonic
• Pneumotachographs

Anaesthesia U.K.
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Design Requirements

• Flow source O2, CO2, or medical air
• Range 0-15LPM
• Readouts single or continuous
• Dimensions 1 x 1 x 4 or 4 x 4 x 1
• Accuracy within 10 of actual flow rate
• Cost lt 2 per flow meter when mass produced

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Rotameter Concepts

• Area is varied to create pressure difference
• Design is flattened to allow for inexpensive
  production
• Plexiglas is clear and durable
• Bead is filled with epoxy serves as float

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Rotameter Testing

• Tested in Dr. Cheslers Lab
• Used Vaseline and beads
• Connected to air source
• Failed to raise float at proper rates

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Venturi Concepts
Obstruction

• Obstruction creates pressure difference
• Water is displaced
• Acrylic used for body
• Tubing is clear and flexible

Gas In
Manometer
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Venturi Testing Pictures
Venturi meter taped to fume hood on black plastic
to aide reading of manometer
Venturi meter in series with calibrated rotameter
for testing
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Venturi Testing Procedure

• Air Testing
• Taped device to fume hood on black plastic
• Performed practice tests to eliminate human error
• Drew lines for 2LPM, 5LPM, 8LPM on manometer
• Read flow rates for 5 trials
• 2LPM flow did not give noticeable readings
• Nitrogen Testing
• Rotamter not calibrated for Nitrogen
• 2LPM flow was noticeable but inaccurate

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Conclusion

• Venturi flow meter works well and meets design
  requirements for a single readout meter
• Accuracy within 10 at more than one flow rate
• Rotameter is ineffective due to dimensions and
  high float density

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Future Work

• Testing of venturi
• Constant flow rate of Nitrogen
• Higher flow rates of air
• Testing of rotameter
• Different dimensions
• Lower float density
• More secure seams

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• Acknowledgements
• Dr. John Webster
• Dr. Naomi Chesler
• Burke ONeal
• The Machine Shop
• Eric Kersten
• References
• Engineering World Health. 28 April 2006.
  http//www.ewh.org/about/index.php
• Anaesthesia U.K. 30 Jan. 2006
  http//www.frca.co.uk/article.aspx?articleid10039
  c0