DESIGN AND IMPLEMENTATION OF

A HIGH VOLUME WATER DEGASSER

 

Brian Glath, Matthew Troutman, and William Lanham

Spring 2006 Senior Design Project

Department of Bioengineering-The Pennsylvania State University

Sponsored by:

Mr. David Francischelli
Medtronic Inc.
Minneapolis, MN

Dr. Nadine Smith
The Pennsylvania State University
University Park, PA
 

Executive Summary

•Ultrasound experiments performed in vitro often use water as a medium to transport the ultrasound waves.
• When this is done, the concentration of dissolved oxygen must be kept minimal because pockets of gas in the water will give inaccurate measurements. 
•To accomplish this, a device called a water degasser can be used to remove the dissolved oxygen from the water.
•These devices are commercially available on the small scale, but are not available for the large scale use (a tank of 50 gallons).
•Our goal was to design and implement a high volume water degasser for use in the medical ultrasound industry.
•The device is powered by a vacuum pump that draws water in from a reservoir where it then works to remove the dissolved oxygen from the water.
•A flow pump is used to move the water from the device back to the reservoir where it will be re-circulated into the device via the vacuum. 
•This design allows the device to continuously run water through the degassing column.

Design Criteria

•A high volume water degasser that works to remove dissolved oxygen in a 40-50 gallon tank within 30 minutes give or take 10 minutes.
•The degassed water will have a maximum concentration of
2 ppm of dissolved oxygen in it.
•The degasser will be compatible with a standard 120-V outlet.
•The device will have easy-to-use controls.
•The surface area inside the chamber will be maximized to provide ample area for the gas to be removed.
•Modify the position of the water filter to give easy access to it.
•Remove as much residual water as possible.
•The project will stay within a $1000.00 budget.

Evaluation

•After construction was completed the device was ran to ensure vacuum sealing had occurred.
•The device was timed to test how long the operating time was.
•The water was tested with a chemical analysis kit to ensure the appropriate concentration of oxygen was present.

Results

•Preliminary testing showed that a concentration of 2 ppm was reached after 30 minutes using a volume of 20 gallons.
•Further testing showed that a plateau was reached after 30 minutes and the concentration could not be reduced below 2 ppm.

Alternative Designs

•A 5 foot long acrylic tube was used instead of a 3 foot long tube to increase the active volume of the chamber.
•A Gast vacuum was taken from an existing model as an alternative to purchasing one.
•A one-way valve was inserted into the outlet hose to prevent the vacuum from drawing water in from the outlet.
•After the base was constructed a shelf had to be made to house the vacuum because there was not enough space for it in the original layout.
•The flange was too large and did not fit the tube, and as a result, PVC rings were cut and placed into the flange to account for the excess space.
•Instant fittings were used in most places to allow for easy removal of the hoses.

Budget

Item Category

Cost

Plastics

$351.17

Flow Pump

$156.62

Construction Materials

$111.59

Bio-Balls

$85.44

Fittings

$85.32

Tubing

$38.62

Showed Head

$37.86

Water Filter

$33.73

Vacuum Pump

$5.25

Silicone

$4.41

Electrical Supplies

$18.63

Total:

$928.64

Final Deliverables

  1. A high volume water degasser that works to remove dissolved oxygen in a 40-50 gallon tank of water within 30 minutes give or take 10 minutes.

  2. The degasser will operate using a water pump and a vacuum that are compatible with a 120-Volt Outlet.

  3. The device will have easy-to-use controls.

Figure 1: An image of the final product.

Figure 2: The inner layout of the device.