1. DETAILED DESIGN REVIEW P13681

2. 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 2

3. Agenda for the review Overview of the Project Our system designs Part designs Lab View layout Bill of Materials Test plans Risk Assessment Schedule for the rest of the Project 3

4. Problem Statement To mass spectrometer UUT High pressure helium Fixturing/leakage similar to other side Fixtures interface between AGT can and UUT Fixture leakage UUT leakage Leakage from Unit UnderTest Leakage from Fixture Leakage from room through lid and baseplate 4

5. Project Overview 5

6. MATLAB/SIMULINK MODEL

7. The System 3000 psi Flow Sensor 0 psi (Vacuum) Case 1) 14.7 psi (ambient) Case 2) 0 psi (Vacuum) Case 3) Variable pressure/vacuum (nitrogen) We require a means to distinguish between the top two generated concepts. Consequently, a math model of the system was created. Results must be an improvement from the baseline

8. Simplification of the System 3000 psi 0 psi (To Mass Spectrometer) Orifice 3 : Accurately simulates uniformly mixed flow out of vent. Orifices 1 and 2: Model Oring Leakage. Entire Vent Volume Flow Sensor Orings will be models as (very) small orifices Molar percentages must be taken into consideration for all three cases (compare apples to apples) HELIUM MIXTURE Cases P vent Initial (N2) P Applied (N2)Notes 114.7 psi This is the baseline 214.7 psi1 psi P vent quickly equalizes to approx 1 psi 314.7 psi 120 psi Note this is not a 50% Duty Cycle 1 psi

9. Parameters and Equations Orifice area, A o, is adjusted for the oring and vent orifices to produce accurate molar flow rates Ideal Gas Law: 3000 psi 0 psi (To Mass Spectrometer) Entire Vent Volume Mixed Density Calculation:

10. Assumptions Most Importantly: This is a pressure driven flow Permeability considerations were made (Parker equations from design review). The leakage rates predicted through the Orings were too small. Perfect gas mixture throughout the volume at all times N2 and He are ideal gases

11. The Simulation Calculate s % Moles Calculates Mixed Density Molar flow rate of gas into/out of vent Molar flow rate of helium into vent (3000 psi) Molar flow rate of gas into can calculator He Integrator N2 Integrator

12. Case 1 : Ambient Vent Pressure High vent pressure causes more total leakage than Case 2 More nitrogen is present; concentration of helium grows slower than in Case 2 Case 2 : Vacuum Vent Pressure Low vent pressure causes less total leakage than Case 1 Less nitrogen is present; concentration of helium grows faster than in Case 1 *Note: He in remains (approximately) constant for both cases ≈ 14.8 psi ≈ 1.1 psi Very High % Helium Moderately High % Helium Red Dots: Helium Blue Dots: Nitrogen ≈ 14.8 psi 14.7 psi 1 psi

13. Total Molar Flow Rate Into Can Question arises: Is it better to have a lower total leakage (lower vent pressure) or a lower percentage of helium in the vent? The simulation should answer this question Below is a plot of the actual molar flow rates into the can Note the order of magnitude As expected, the total molar flow rate is less for Case 2

14. % Helium in Can The concentration of helium grows at a rapid rate when less N2 is present in the vent At the beginning of the response, Case 2 exhibits a lower concentration of helium than Case 1 Note the order of magnitude

15. What Does This Tell Us? Graphed below are the results for the volume of the total leakage for cases 1 and 2: Over the full interval, the model predicts that Case 2 An improvement is not expected for a constant vacuum scenario. A constant vacuum does show an improvement in can leakage for the full test duration This duration of this improvement grows as the vent volume is increased Full 6 Minutes Early Region (2.5 seconds)

16. Cases 1 and 2 With Increased Vent Volume For a significantly increased volume: The positive influence of Case 2 lasts for approximately 175 seconds (as opposed to 2 seconds). That being said, the remainder of the results will assume that the vent volume is the nominal calculated value (8.49E-7 m 3 )

17. Cases 1 and 2 Conclusions Concentration of helium in vent dominates the response of the simulation Case 2 would show a significant improvement over Case 1 if: The % He was allowed to grow near 100% in both cases (within the allotted time interval) The vent volume was significantly increased A Case is needed which actively reduces the concentration of helium in the vent. A marked improvement over Case 1 is expected

18. Case 3 Concept 1. Nitrogen is forced in at above ambient pressure: % Helium increases over time 2. Uniform mixture of gas molecules are removed from the vent: % Helium remains about same. 120 psi N2 ≈ 120 psi Mixture ≈ 1 psi Mixture

19. Case 3 Concept Continued 3. Nitrogen is once again forced into the vent: % Helium Drops (Note total percentage still > step 1) 3. Repeat step 2 and 3 throughout the 6 minute external leakage test. The percentage of helium will inevitably grow, but at a slower rate than cases 1 or 2. ≈ 120 psi Mixture

20. Determining the Frequency of Pulse/Purge Previous slides indicated that pulling a vacuum is only beneficial for approximately 2 seconds. Consequently the following duty cycles for varying input signal periods were calculated: Values of 120 psi pulse pressure and 1 psi purge pressure were selected Period (s)Duty Cycle (%) 1020 10 306.7 405 1 Period 1 psi 120 psi

21. Case 3 Results Integration

22. Case 1 to Case 3 Comparison The best curves of Case 3 are now compared to baseline: A significant improvement is noted for Case 3

23. Simulation Conclusion A case 3 scenario shows a marked improvement over the current setup This model will be used as a tool in MSDII to fine tune the system to optimize can leakage prevention

24. Areas of Desired Feedback After seeing the results, is the magnitude of can leakage accurate? If not, the size of the orifices will be adjusted accordingly Is the 8.49E-7 m 3 vent volume accurate? Note that this is 84.7 mm 3

25. System Layout 25

26. Cycling Valve 26 GN2 Vacuum To the small o-ring

27. Enclosure 27

28. Pipeline model 28 Some type of relief structure will be in place here Wires exit rear To small vent From Vacuum Source To large o-ring From Nitrogen Source 3-way valve 2-way valve Regulator

29. Mounting to the can 29

30. Through the Manifold 30

31. Port Blocks 31

32. The Plug 32

33. Mounting to the side of the can 33

34. Pressure Vessel Analysis: Plug A pressure vessel analysis was ran for the plug geometry. This geometry was selected due to the thin walls Due to the thin walls this is considered the worst case geometry Failure margins were calculated with a 1.1 factor of safety. Note all margins are positive.

35. Material Properties Plugs assumed to be machined from structural steel (properties taken from ANSYS library): F ty = 36.3 ksi F tu = 66.7 ksi μ = 0.3 E = 2.9E7 psi

36. Mesh 2 cells through thickness achieved 472699 Nodes 311215 Tetrahedral Elements (Overkill)

37. Loads and Boundary Conditions Nominal Loading Worst Case Loading Fixed Support

38. Nominal Loading Results Maximum stress: 9675 psi

39. Worst Case Loading Results Maximum stress: 9675 psi

40. Margin Calculation Margin for yield in the worst case loading scenario is negative. All others are positive This is due to a high stress at the part surface. The net section stress will now be studied. Margin Table Load CaseYield/UlimateAllowableActualF.S.Margin Nominal Yield36.391.10.72 Ultimate66.791.10.85 Worst Case Loading Yield36.333.91.1-0.03 Ultimate66.733.91.10.44

41. Worst Case Loading: Net Section Stress Load Path Average stress is calculated for the load path shown. New margins are calculated

42. Net Section Margins Net section margins are positive The part is deemed to be safe for cleanroom usage Margin Table Load CaseYield/UlimateAllowableActualF.S.Margin Worst Case Loading Yield36.38.61.1.74 Ultimate66.78.61.1.85

43. LabView Layout 43

44. Wire Diagram 44 Each valve has 2 leads for a circuit. They will be connected to a terminal block and then to a terminal block on the AGT system

45. Bill of materials 45

46. Test plans 46 Spec. #FunctionTestNominalPass/FailUnitsOrder of Testing 1Reduction of Test gas Leakage Run external leakage test at Moog with their current system using a blank instead of a valve and new O- rings. Run external leakage test with the new system under the same conditions. Verify the reduction percentage of helium comparing both results. Redo both tests using used O-rings. 90%±5%cm 3 /sec 3 2Amount of Nitrogen Measure the amount of nitrogen flowing into the system using a flowmeter while the external leakage test is in operation with the new system <100N/Ascc/min 3Constant Leak Detection Run external leakage test using a blank instead of a valve and record the leakage value reading the mass spectrometer every 30 seconds. ±5%N/Acm 3 /sec 4Training Time An overview document will be created in order to explain the new system and how it works. In addition, a short presentation will be given to an operator and questions will be answered. This process will be timed from beginning to end. <30N/Amin4 5Pressure Condition Each part model will be run through finite element analysis to verify that all parts can work together under this pressure <3500N/Apsi1 6Cost Create Bill Of Materials and verife that the Total cost for one System doesn't exceed the budget <=8000N/A$2

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48. Our schedule for MSDII 48