Plant Operator Selection System Test Plant Operator Selection System Tables and Graphs Interpretation 4 — Questions and Answers
Question 1: A table shows chemical feed rates needed at different flow levels: 100 gpm→2.0 lb/hr, 200 gpm→4.0 lb/hr, 300 gpm→6.0 lb/hr. If the current flow is 250 gpm, what feed rate is required?
- 5.0 lb/hr (Correct answer)
- 4.5 lb/hr
- 5.5 lb/hr
- 4.0 lb/hr
Correct answer: 5.0 lb/hr
The ratio is 0.02 lb/hr per gpm, so 250 × 0.02 = 5.0 lb/hr.
Question 2: A dual-axis graph plots temperature (°F, left axis) and pressure (psi, right axis) over time. When temperature spikes at 2pm, pressure shows a corresponding dip. This indicates:
- An inverse relationship between temperature and pressure at that time (Correct answer)
- Both variables are unrelated
- Pressure controls temperature
- The graph contains an error
Correct answer: An inverse relationship between temperature and pressure at that time
When one variable increases while the other decreases at the same moment, they show an inverse (negative) relationship.
Question 3: A maintenance frequency table shows: Pump A serviced every 500 hours, Pump B every 750 hours, Pump C every 1,000 hours. After 3,000 hours of operation, how many total service events have occurred across all three pumps?
- 13 (Correct answer)
- 10
- 11
- 12
Correct answer: 13
Pump A: 3000/500=6; Pump B: 3000/750=4; Pump C: 3000/1000=3; total = 6+4+3 = 13.
Question 4: A histogram shows the distribution of particle sizes in a batch. The tallest bar is at the 50–60 micron range. This bar represents the:
- Mode (Correct answer)
- Mean
- Median
- Range
Correct answer: Mode
The tallest bar in a histogram represents the most frequently occurring value range, which is the mode.
Question 5: A trend graph shows that tank level has been declining at a constant rate of 3 inches per hour. The tank is currently at 48 inches. At this rate, when will it reach the low-level alarm set at 12 inches?
- 12 hours (Correct answer)
- 16 hours
- 9 hours
- 4 hours
Correct answer: 12 hours
(48 − 12) / 3 = 36 / 3 = 12 hours until the alarm level is reached.
Question 6: A table compares two heat exchangers. HX-1: inlet temp=200°F, outlet temp=140°F. HX-2: inlet temp=210°F, outlet temp=160°F. Which exchanger has a greater temperature drop?
- HX-1 with a 60°F drop (Correct answer)
- HX-2 with a 60°F drop
- HX-2 with a 50°F drop
- Both have the same drop
Correct answer: HX-1 with a 60°F drop
HX-1 drop = 200 − 140 = 60°F; HX-2 drop = 210 − 160 = 50°F; HX-1 has the greater drop.
Question 7: A line graph shows reactor conversion efficiency (%) over six months: Jan=82, Feb=85, Mar=83, Apr=88, May=86, Jun=91. What is the overall trend?
- Gradually increasing (Correct answer)
- Stable with no change
- Steadily decreasing
- Highly volatile with no trend
Correct answer: Gradually increasing
Despite minor month-to-month fluctuations, the overall direction of the data points is upward from 82% to 91%.
Plant Operator Selection System Test Plant Operator Selection System Tables and Graphs Interpretation 4
A table shows chemical feed rates needed at different flow levels: 100 gpm→2.0 lb/hr, 200 gpm→4.0 lb/hr, 300 gpm→6.0 lb/hr.
If the current flow is 250 gpm, what feed rate is required?