moog gas evacuation systems design review

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Austin FrazerEileen KobalAna Maria MaldonadoMarie Rohrbaugh

Moog Gas EvacuationSystems Design Review

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The Team Austin Frazer

Role: Lead Engineer - Analysis Major: Mechanical Engineering

Eileen Kobal Role: Lead Engineer – Mixtures

of Gas Fluids Major: Chemical Engineering

Ana Maria Maldonado Role: Team Manager Major: Industrial Engineering

Marie Rohrbaugh Role: Project Manager Major: Mechanical Engineering

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Problem Statement

To mass spectrometer

UUT

High pressure helium

High pressure helium

Fixturing/leakage similar to other side

Fixtures interface between AGT can and UUT

Fixture leakageUUT leakage

Leakage from Unit Under TestLeakage from FixtureLeakage from room through lid and baseplate

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Current Procedure

Our process needs to minimize leakage from fixtures

Oring Leakage Diagram

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VOC to

VOE customer

rating

Mate with the

current softwar

e system

No extra procedur

e is required to make

the system

run

The system starts when

the test starts

Nitrogen

moves when

the system is

told to start

<5 sec between start of test

and equilibri

um

Reduce the

leakage into the can to 1% of

original value

No adjustment made to

original design

<100scc

/min of

Nitroge

n used

Maintenance plans

provided

Training

materials provided

cost of system is

<$10,000

time betwee

n mainten

ance cycles is

>30 days

FMEA performed

training

takes

<30 min

provide accurate test data 10 * * *

Preserve Vacuum 1 *

Reduce delay caused by false failures 7 * *

minimize increased cycle time 8 * * * * * *

user safety 12 * *

operator understands process 3 * * *

system is controlled transparently by the existing software 9 * *

minimize cost by balancing initial cost, maintenance cost, and consumable

materials6 * * * * * *

sturdy and robust system 11 * *

maximize time between maintenance cycles 4 * *

maintenance plans 5 *

maintenance can be accomplished with minimal money and time 2 * * *

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Voice of the Engineer

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Design Constraints Safety Contamination

Class 10,000 clean room. All products should comply to a strict

cleanliness certification Existing Fixture

Cannot modify inside of can Must be attachable to can

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Resources Gas Flow

Nitrogen gas at 120psia available Vacuum at 1psia available

Hardware (possibly) People

Moog professionals Guides Professors

Budget 7,500 per system

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Function Tree

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Concept Generation

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Pugh Diagram- Move/ Evacuate the Gas

Comparison Concept A B C D

small centrifugal pump to draw

out test gas

heating / cooling a

reservoir of inert gas to

draw out test gas

additional mass spectrometer at the vent draws

out test gassmall vacuum

pump

alternating drawing down

the test gas and pumping with a

flush gasCriteria Weight

Application elsewhere at Moog 1 0 -1 1 0 0Availability of resources 7 0 -7 -7 0 0Contamination possibility 9 0 0 0 0 0Cost 8 0 -8 -8 0 -8Durability (everyday use) 7 0 -7 0 0 0Effectiveness 9 0 -9 9 9 9Fits timeline 10 0 -10 0 0 0Long term benefits 5 0 0 0 0 0Maintainable 5 0 -5 0 0 0Meets space limitations 8 0 0 0 0 0Safety 10 0 0 0 0 0Works transparently with current system 9 0 0 -9 0 0 0 -47 -14 9 1

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Pugh Diagram- Access the Gas

Comparison

Concept A B C

larger cavity for gas collection

modify vent geometry

fill vent with a viscous fluid to

prevent He from entering

have a different o-ring material so that the He

doesn't go through

Criteria Weight

Application elsewhere at Moog 1 0 0 -1 1

Availability of resources 7 0 0 -7 -7

Contamination possibility 9 0 0 -9 -9

Cost 7 0 -7 7 -7

Durability (everyday use) 7 0 0 -7 0

Effectiveness 9 0 9 -9 0

Fits timeline 10 0 0 0 0

Long term benefits 5 0 0 -5 0

Maintainable 5 0 0 -5 5

Meets space limitations 8 0 0 8 8

Safety 10 0 0 10 0

Works transparently with current system 9 0 0 -9 9

0 2 -27 0

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Block Diagram

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Flexline to Nitrogen Source

Flexline to Vacuum Source

To vent

To large o-ring X2

Relief Valve

AN Fitting

2-way 2-position solonoid valve

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Flexline to Nitrogen Source

Flexline to Vacuum Source

To vent

To large o-ring X2

Relief Valve 3-way 2-

position solonoid valve

AN Fitting

2-way 2-position solonoid valve

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Analysis Performed – Simscape Model

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Simscape Free Body Diagram

3000 psi 0 psi (To Mass Spectrometer)

Orifice 3 : Accurately simulate sflow out of vent. Required: Cd(vent), A(vent)

Orifices 1 and 2: Model Oring Leakage. Required: Cd(Oring), A(Oring)

Entire Vent Volume

Case 1) 14.7 psi (baseline)Case 2) 0 psi (Vacuum)Case 3) Variable pressure/vacuum (nitrogen)

Flow SensorPressure Sensor

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Analysis Performed – Simscape Model

Case 1)

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Analysis Performed – Simscape Model

Case 2)

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Analysis Performed – Simscape Parameters

Model Orings as Orifices

 1  2 𝐾=𝜌

2𝐶𝑑2 𝐴2

𝛿𝑃=𝑃1−𝑃2

L = Approximate leak rate of the seal, std. cc/sec.F = Permeability rate of the gas through the elastomer at the anticipated temperature, std. cc cm/cm2 sec bar. (example: Butyl's permeability at 77oF with Acetylene is 1.26 x 10-8 std. cc cm/cm2 sec bar)D = Inside diameter of the O-ring, inches.P = Pressure differential across the seal, lb/in2 .Q = Factor depending on the percent compression and whether the O-ring is lubricated or dry (from figure 3 below)S = Percent compression on the O-ring cross section expressed as a decimal (i.e. for 20% compression, S = 0.20)

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Diffusion

Diffusion Coefficient for 2

gasses

Diffusion Flux: Movement due to

Diffusion across an area

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Gantt Diagram

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Risk Assessment

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Questions??