PO Quality Control & Sampling 1 — Questions and Answers
Question 1: Why is it important to flush a sample point before collecting a process sample?
- To warm up the sampling equipment
- To purge stagnant or unrepresentative material from the line (Correct answer)
- To meet OSHA confined space requirements
- To reduce sample volume for the laboratory
Correct answer: To purge stagnant or unrepresentative material from the line
Flushing purges dead-leg material that does not represent current process conditions, ensuring the collected sample is truly representative.
Question 2: What is a 'composite sample' in process sampling?
- A sample taken only from the top of a vessel
- A sample formed by combining multiple grab samples over time or location (Correct answer)
- A sample tested by multiple laboratories
- A sample that has been filtered and dried
Correct answer: A sample formed by combining multiple grab samples over time or location
A composite sample is created by mixing several individual samples collected at different times or locations to represent an average condition.
Question 3: Which of the following is the correct chain of custody purpose in process sampling?
- To track sample shipping costs
- To document sample integrity from collection through analysis (Correct answer)
- To ensure the sample reaches the lab quickly
- To assign responsibility for sample disposal
Correct answer: To document sample integrity from collection through analysis
Chain of custody documents who handled the sample and when, ensuring its integrity and traceability from the point of collection to final analysis.
Question 4: A process sample is collected in the wrong container material and the analysis results are anomalous. What is the most likely cause?
- The laboratory equipment was uncalibrated
- The sample was contaminated or adsorbed by the incompatible container (Correct answer)
- The process was operating normally
- The operator sampled at the wrong frequency
Correct answer: The sample was contaminated or adsorbed by the incompatible container
Using an incompatible container can cause sample contamination or analyte adsorption to container walls, producing false analysis results.
Question 5: What does 'specification limits' mean in the context of process product quality?
- The legal maximum throughput for a unit
- The defined acceptable range of product properties for customer or process requirements (Correct answer)
- The maximum instrument measurement range
- The pressure limits for a pipeline
Correct answer: The defined acceptable range of product properties for customer or process requirements
Specification limits define the minimum and maximum acceptable values for product quality parameters required by customers or downstream processes.
Question 6: When a product quality parameter trends toward its control limit, the operator should:
- Wait until the limit is exceeded before acting
- Take corrective action to adjust the process before the limit is reached (Correct answer)
- Increase sampling frequency only
- Shut down the unit immediately
Correct answer: Take corrective action to adjust the process before the limit is reached
Proactive adjustment when a parameter trends toward a control limit prevents out-of-spec production and maintains product quality.
PO Quality Control & Sampling 1
Why is it important to flush a sample point before collecting a process sample?