PE Mechanical case studies
PE Mechanical · Put your knowledge to work in context.
The PE Mechanical is the licensure examination mechanical engineers take as the final exam step toward a professional engineer (PE) license in the United States. NCEES develops and administers it, and the state licensing board in your jurisdiction sets eligibility rules, reviews your education and experience, and issues the license. The PE Mechanical case studies are 5 cases and about 3,877 words.
1High Space Humidity After an Economizer Actuator Replacement
A 10,000 cfm central AHU serves a 12,000 ft² office and is designed for 20% outdoor air. Design conditions are 95°F DB/78°F WB outdoors and 75°F DB/50% RH indoors, with the coil leaving 55°F DB and a coil SHR of 0.67.
710 words, about 4 min2Chiller Plant Sizing: Sum of Zone Peaks vs. Coincident Block
A 14-story office tower has 12 AHUs and one central chilled-water plant. The load report lists a sum of zone peaks of 520 tons and a coincident block of 410 tons from the same simulation run.
766 words, about 4 min3Enthalpy Wheel on Class 4 Laboratory Exhaust
A 100% outdoor-air laboratory building supplies 24,000 cfm and exhausts 24,000 cfm from chemistry fume hoods. Winter design is -5°F DB; lab exhaust is 72°F at 40% RH.
748 words, about 4 min4Centrifugal Chiller With Both Approaches Elevated
A 500-ton water-cooled centrifugal chiller (R-134a) is rated 0.55 kW/ton at AHRI conditions. At a measured 400-ton load the operator logs: chilled water 54°F in/44°F out; refrigerant saturation 36°F; condenser water 85°F in/95°F out; refrigerant saturation 101°F; compressor 260 kW; oil pressure and level normal; no surge or abnormal noise.
714 words, about 4 min5VAV Boxes Starving With the Static Sensor at Setpoint
A 22,000 cfm AHU with a VFD-driven forward-curved fan serves 30 VAV boxes through 180 ft of medium-pressure duct. The duct static pressure sensor is tapped 15 ft downstream of the fan discharge in a straight run; the setpoint is 1.5 in.
939 words, about 5 min