Examkin

Question

Difficulty: HardSequential Detail Extraction

Read the following technical passage describing a spacecraft maintenance protocol:

"Prior to servicing a spacecraft's hypergolic thruster manifold, technicians must execute a four-stage decontamination sequence. First, the isolation valves are closed and residual liquid is drawn down into the vacuum scavenger sump. Before introducing high-purity nitrogen for the intermediate purge, technicians must verify that line pressure drops below five millibars. Following the triple-cycle gaseous nitrogen flush, the moisture sensor port is uncapped to sample the residual vapor content. Only after the moisture baseline is confirmed acceptable do operators seal the vent manifold and apply a positive-pressure helium blanket to stabilize the system."

Based on the passage, match each procedural stage with its corresponding mandatory action.

  • Initial fluid evacuationClose isolation valves and route residual propellant into the vacuum scavenger sump
  • Pre-purge qualificationVerify line pressure drops below five millibars
  • Post-flush evaluationUncap the sensor port to measure residual vapor content
  • System stabilizationSeal the vent manifold and apply a positive-pressure helium blanket

Answer

Initial fluid evacuation matches with closing isolation valves and routing residual propellant into the vacuum scavenger sump; Pre-purge qualification matches with verifying line pressure drops below five millibars; Post-flush evaluation matches with uncapping the sensor port to measure residual vapor content; System stabilization matches with sealing the vent manifold and applying a positive-pressure helium blanket.
Each phase corresponds chronologically and functionally to explicit procedural cues in the text: 'First' introduces the scavenger drawdown, 'Before introducing...' dictates the 5-millibar pressure verification, 'Following...' governs moisture port uncapping, and 'stabilize the system' defines the helium blanket application.

Step-by-Step Solution

1
Locate the chronological marker for the first stage.
The indicator 'First' introduces closing isolation valves and evacuating liquid to the vacuum scavenger sump.
This establishes the initial fluid evacuation pair.
2
Identify the precursor condition linked to the intermediate purge.
The phrase 'Before introducing high-purity nitrogen' specifies verifying pressure below five millibars.
This pairs the pre-purge qualification stage with its pressure threshold check.
3
Identify the event immediately following the nitrogen flush.
The transition 'Following the triple-cycle gaseous nitrogen flush' points to uncapping the moisture sensor port for vapor sampling.
This defines the post-flush evaluation pair.
4
Extract the terminal action that accomplishes system stabilization.
The concluding conditional sentence indicates sealing the vent manifold and applying a positive-pressure helium blanket.
This establishes the final system stabilization match.

Key Concept

Sequential Detail Extraction
Estimated Time:1m 30s
Rate this question

Topics

Sequential Detail Extraction

More questions from this topic