Module 2 — Graded Quiz (Summative)

20 questions

0 of 20 answered All questions must be answered to submit

Question 1 — Question 1

The following rate-of-rise data is recorded on R1-A after isolation at 0.06 mbar: 1 min → 0.18 mbar, 2 min → 0.30 mbar, 5 min → 0.66 mbar, 10 min → 1.26 mbar. What does this pattern indicate?

A. Normal outgassing — the rate decreases over time
B. A real leak — the rate is approximately constant at ~0.12 mbar/min
C. A virtual leak — the rate increases over time
D. Gauge malfunction — the readings are too consistent

Question 2 — Question 2

During roughing on R1-A, the pressure drops normally from 950 to 1 mbar but then takes 25 minutes to drop from 1 to 0.1 mbar. The pump sounds normal and a previous pumpdown last week reached 0.05 mbar in 8 minutes. What is the most likely explanation?

A. The pump has degraded since last week
B. Increased gas load from surface contamination or water (the system was likely opened or handled between runs)
C. A major air leak that only affects low-pressure performance
D. The chamber volume has somehow increased

Question 3 — Question 3

Which of the following gas load sources produces a CONSTANT gas load that does NOT decrease over time?

A. Surface-adsorbed water
B. Outgassing from chamber walls
C. Virtual leak from a trapped volume
D. Real leak from a damaged O-ring

Question 4 — Question 4

On R1-A, R1-FLT-VENT is a sintered metal filter on the vent line. After a controlled vent, an operator discovers fine particles inside the chamber that were not present before venting. Which of the following is the LEAST likely explanation?

A. The vent filter element is degraded or saturated and no longer captures fine particles
B. The vent valve was opened too quickly, creating turbulence that bypassed the filter
C. A technician vented by cracking the chamber flange instead of using the vent line
D. The particles were generated by the roughing pump during the previous pumpdown

Question 5 — Question 5

A technician handles fixtures inside the R1-A chamber without gloves. The next pumpdown shows the system reaching 0.30 mbar instead of the normal 0.05 mbar base pressure. What type of contamination is most likely responsible?

A. Particulate contamination from skin flakes
B. Hydrocarbon contamination from fingerprint oils
C. Water contamination from perspiration
D. Metallic contamination from jewellery

Question 6 — Question 6

A rate-of-rise test is performed on R1-A. The rate decreases from 0.15 mbar/min to 0.02 mbar/min over 15 minutes. The system is pumped down again, re-isolated, and the test is repeated. The second test shows an identical pattern — same starting rate, same decrease. What should you suspect?

A. Normal outgassing (confirmed by the decreasing rate)
B. A virtual leak — the trapped volume refills during pumpdown and produces the same release pattern each cycle
C. A real leak that happens to vary over time
D. Gauge hysteresis causing false readings

Question 7 — Question 7

Base pressure depends on the balance between total gas load entering the chamber and the effective pumping speed removing it. A colleague proposes installing a pump with twice the pumping speed to halve the base pressure. Why is this reasoning often incorrect in practice?

A. Pumping speed cannot be doubled
B. If the dominant gas load comes from contamination or leaks (rather than the pump being too small), doubling pump speed only marginally reduces base pressure because the gas load remains unchanged
C. The relationship between gas load and pumping speed only applies in viscous flow
D. Base pressure is independent of pump speed

Question 8 — Question 8

On R1-A, the system is in ISOLATED state. R1-G-CH reads 0.10 mbar and rises to 0.25 mbar in 5 minutes, then to 0.35 mbar in the next 5 minutes. The corresponding rates of rise are 0.03 mbar/min in the first interval and 0.02 mbar/min in the second interval. What does this trend indicate?

A. 0.03 mbar/min then 0.02 mbar/min — decreasing rate, normal outgassing
B. 0.03 mbar/min then 0.03 mbar/min — constant rate, real leak
C. 0.05 mbar/min then 0.10 mbar/min — increasing rate, catastrophic failure
D. Cannot be determined from this data

Question 9 — Question 9

A chamber has been at atmosphere for two weeks. The first pumpdown of the day takes 20 minutes to reach 0.1 mbar. After venting and immediately pumping again, the second pumpdown takes only 12 minutes to reach 0.1 mbar. What explains the improvement?

A. The pump warmed up and is now more efficient
B. The chamber cooled down between cycles
C. The first pumpdown removed a significant amount of surface water; with less water to desorb on the second cycle, the pumpdown is faster
D. A leak sealed itself during the first pumpdown

Question 10 — Question 10

Pump oil backstreaming on R1-A is most likely to occur under which conditions?

A. During bulk gas removal at 950 mbar
B. When the pump runs at low pressure with the chamber at base pressure and very little gas flow
C. During controlled venting through R1-FLT-VENT
D. When the isolation valve is closed

Question 11 — Question 11

A technician reports that R1-A reached a base pressure of 0.08 mbar, which is higher than the normal 0.05 mbar. The system was cleaned and dried properly before this pumpdown. A rate-of-rise test shows a constant rate of 0.03 mbar/min. What is your assessment?

A. Normal outgassing — 0.08 mbar is close enough to 0.05 mbar
B. A minor real leak — the constant rate of rise indicates a small but steady gas ingress, which also explains the elevated base pressure
C. Contamination from the cleaning process
D. The gauge needs recalibration

Question 12 — Question 12

Which gas load source is most effectively reduced by baking out the chamber (heating to 150–250°C under vacuum)?

A. Surface-adsorbed water and outgassing from chamber walls
B. Real leaks through damaged O-rings
C. Permeation through metal chamber walls
D. Bulk atmospheric gas

Question 13 — Question 13

On R1-A, during a rate-of-rise test, the pressure rises from 0.05 to 0.55 mbar in the first minute (rate: 0.50 mbar/min). Is this rate consistent with normal outgassing?

A. Yes — all rate-of-rise values are normal during the first minute
B. No — 0.50 mbar/min is far too high for normal outgassing at rough-vac pressures; this suggests a significant leak or gross contamination
C. It depends on the chamber volume
D. Outgassing rates cannot be estimated at these pressures

Question 14 — Question 14

A vacuum system that has been cleaned with an acetone rinse shows extended pumpdown times. The operator is puzzled because acetone is a "good cleaner." What is the most likely cause?

A. Acetone damaged the pump seals
B. Acetone reacted with the chamber metal
C. Residual acetone (a volatile organic compound) left on surfaces is slowly evaporating under vacuum, creating an additional gas load
D. Acetone increased the chamber volume

Question 15 — Question 15

An RGA mass spectrum from a vacuum system shows dominant peaks at mass 28 and mass 32 in approximately a 4:1 ratio. What does this spectrum most likely indicate?

A. Water contamination
B. An air leak — nitrogen (mass 28) and oxygen (mass 32) in atmospheric ratio
C. Pump oil backstreaming
D. Normal outgassing from metal surfaces

Question 16 — Question 16

During R1-A roughing, R1-G-CH drops from 950 mbar to 100 mbar in 30 seconds. At which point during this initial pumpdown phase is the gas flow regime transitioning from viscous to molecular flow?

A. At 950 mbar — the transition begins immediately
B. At 100 mbar — the transition is already complete
C. The transition occurs gradually in the range from roughly 1 to 0.01 mbar, which is well below this phase
D. The transition depends on temperature, not pressure

Question 17 — Question 17

You are writing a diagnostic report for R1-A. Which of the following statements demonstrates the best evidence discipline for a Module 2 assessment?

A. "The system seems to be leaking based on my experience with similar systems."
B. "R1-G-CH is too high. Something is wrong."
C. "Rate-of-rise test (ISOLATED, starting 0.06 mbar): 0.12 mbar/min at 1 min, 0.12 mbar/min at 5 min, 0.11 mbar/min at 10 min. Constant rate suggests real leak at ~0.12 mbar/min. Evidence indicates leak investigation should focus on R1-V-ISO seal and chamber O-ring."
D. "I checked the system and it's leaking. We should replace the pump."

Question 18 — Question 18

A system is pumped down and isolated three times in succession. The rate-of-rise data shows: Run 1: 0.15 mbar/min initial. Run 2: 0.08 mbar/min initial. Run 3: 0.04 mbar/min initial. What does the decreasing initial rate across runs indicate?

A. A real leak that is gradually sealing itself
B. Each pump-down cycle removes more surface gas, so less remains to desorb in subsequent runs — confirming outgassing (or water contamination) as the dominant gas source
C. The pump is improving with each cycle
D. The gauge is drifting low over time

Question 19 — Question 19

On R1-A, R1-FLT-EXH (oil mist filter) is located on the exhaust line. Its primary function is to:

A. Prevent atmospheric particles from entering the chamber during venting
B. Filter the gas before it enters the pump
C. Capture oil aerosol from the pump exhaust before it enters the workspace
D. Reduce the noise of the pump exhaust

Question 20 — Question 20

You review the following information about R1-A:

A. System was opened for 30 minutes to load a new sample
B. Operator wore nitrile gloves and used clean tools
C. Venting was performed slowly through R1-FLT-VENT
D. First pumpdown after loading takes 18 minutes to reach 0.1 mbar (normal is ~8 minutes)
E. Rate-of-rise test shows decreasing rate (0.08 → 0.03 mbar/min over 10 minutes)
F. Real leak introduced during sample loading — needs immediate repair
G. Pump degradation — the pump should be serviced
H. Elevated surface water from 30-minute exposure to atmosphere — no leak (rate decreasing), handling was clean, expect performance to improve with additional pump-down cycling
I. Vent filter failure — particles contaminated the chamber

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Graded Quiz