Mass Flow Controller System

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					Mass Flow Controller System
Client: Brad Hodgeman– Instrumentation Specialist, Comparative Biosciences Advisor: Professor Emeritus John G. Webster Team Members: Aaron Huser, Cole Kreofsky, Dana Nadler, Joe Poblocki

University of Wisconsin - Madison Biomedical Engineering Design Courses INTELLECTUAL PROPERTY STATEMENT

Problem Motivation
Hodgeman researches hypoxia and hyperoxia with rats at the Veterinary Science Building.  Current mass flow controllers are too inaccurate, and the software is outdated.  There are undesirable, manual aspects to protocol that need to be eliminated.
 Brad

Problem Statement
The purpose of this project is to design a system that can create a reproducible and accurate hypoxic/hyperoxic environment with the capability of oscillating between various concentrations of oxygen and nitrogen.

Background


Hypoxia and hyperoxia are atmospheric conditions, where the oxygen level deviates below or above normal (21%) concentration, respectively. Hypoxia is a form of respiratory distress which induces certain physiological responses by the neuro-respiratory system. These responses have been associated with SIDS, sleep disorders, spinal cord injury, etc.

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Mass Flow Controllers
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Mass flow controllers often aid in hypoxia research due to their ability to alter Oxygen concentrations to desirable levels for testable consequences.

Current Gas Control System
controlled Command Module (HyperTerminal Software)  Four Analog Mass Flow Controllers  Two Manual Mass Flow Controllers  Four Chambers
 Computer

Design Constraints
gas concentrations and flow rates through a chamber  Software with an easy to use interface and customizable features  Accurate mass flow controllers, digital or analog  Uniform tubing resistance  Low sound level  Capability for further expansion
 Variable

Software Development
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LabVIEW
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Graphical programming environment made for engineers and scientists Client has had previous experience using DASYLab – a program similar to LabVIEW Ability to customize programs easily and efficiently Variety of open source examples of current programs available

Main Areas of Focus
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Mass Flow Controller Manufacturers
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Sierra Instruments – Series 100 Smart-Trak™ Advanced Energy – Aera® Mach One Mykrolis – Intelliflow ™ II
Analog Digital
DeviceNet  RS485  RS232
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Interface types
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Manufacturer Matrix
Company Advanced Energy Mykrolis Sierra Instruments Accuracy +/- 0.5% (4) +/- 0.25% sp plus 0.35% fs (3) +/- 0.7% of reading + 0.3% fs (2) Response Time <= 250 ms (5) 1 sec (3) 2 sec (2) Price $1675.00 US (3) $1880.00 US (2) $1370.00 US (4) Customer Service (3) (3) (4) Flow Range 3 L/min (2) 5 /min (5) 6 L/min (4) Total

17** 16 16

Low=1 - 5=High

**The Numbers Don't Lie!

Digital vs. Analog
Digital  Accuracy is a function of set point (sp)  Multiple gas calibration curves  Multiple set point calibration  More cost efficient Analog  Accuracy is a function of full scale (fs)  Manual individual gas calibrations

Digital Interface
DeviceNet
Most Expensive  Too sophisticated for this system
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RS232
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Least Expensive Ergonomically incompatible

RS485
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Moderately Expensive Ability to daisy-chain cables

LabVIEW software, RS485 interface and AE MFCs

System Design

Questions

Any Questions?