🔍 Key Concepts

• Trace the oil flow path through the preheater in the MO-0127 diagram, noting where temperature is sensed ‘after preheater’. • Consider how steam-side conditions (control valve, steam trap, condensate removal) affect oil outlet temperature from the heater. • Compare the effects of restricted heat transfer (fouling) vs. excessive heat input on the oil temperature after the preheater.

💭 Think About

• Looking at the illustration, what change would make the steam-to-oil heat exchanger transfer more heat to the oil, rather than less? • Which option would most likely cause the temperature sensor located after the preheater to see a higher-than-normal outlet temperature under the same oil flow rate? • How would a properly working steam trap affect condensate level in the heater shell and the overall heating efficiency—would that tend to raise or stabilize/reduce oil temperature?

✅ Before You Answer

• Identify exactly where in the illustration the temperature element after the preheater is located and how it is labeled. • For each choice, decide if it would increase or decrease the rate of heat transfer from steam to oil and therefore the oil outlet temperature. • Eliminate any option that would realistically cause lower oil temperature, heater flooding, or reduced steam-side pressure rather than a genuine ‘high oil temperature after preheater’ alarm.