Advanced Diagnostics & Troubleshooting Flashcards
7 cards from real CPT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Advanced Diagnostics & Troubleshooting flashcards as text
A distillation column has high overhead product purity but low bottoms purity. The MOST appropriate corrective action is to:
Answer: Increase reboiler duty to increase vapor traffic
Low bottoms purity indicates insufficient separation in the stripping section; increasing reboiler duty drives more vapor upward to strip light components from the bottoms.
A control loop with integral action is said to have 'integral windup.' What causes this condition?
Answer: The controller output is saturated while error persists
Integral windup occurs when the controller output is saturated (at 0% or 100%) but the error continues, causing the integral term to accumulate excessively.
When analyzing a pump curve against a system curve, what does the intersection point represent?
Answer: The actual operating flow and head of the system
The intersection of the pump curve and system curve defines the actual operating point where pump head equals system resistance at a given flow.
A pressure relief valve is simmering (weeping) below its set pressure. What is the MOST likely cause?
Answer: The valve disc is corroded or has debris on the seat
Debris or corrosion on the valve seat prevents a tight shutoff, causing the valve to leak (simmer) at pressures below the set point.
An infrared thermometer reads lower than a contact thermocouple on the same surface. The MOST probable reason is:
Answer: The infrared thermometer emissivity setting is too high
If the IR thermometer emissivity setting is higher than the actual surface emissivity, it will calculate and report a lower temperature than actual.
A fired heater shows a rising stack temperature over several weeks with constant fuel and process flow. The MOST likely cause is:
Answer: Coke or fouling buildup on the radiant tubes
Fouling or coking on radiant tubes reduces heat transfer to the process fluid, so more heat exits via the stack instead of being absorbed.
When troubleshooting an interlock that will not reset after a process upset, the FIRST check should be:
Answer: Verify all process conditions have returned to within normal operating limits
An interlock will not reset until all initiating conditions are cleared; confirming all process variables are within normal limits is the mandatory first step.