NIULPE 4th Class study guide
NIULPE 4th Class · Work through your exam, one topic at a time.
The NIULPE 4th Class Engineer certification is an entry-level power engineer credential administered through the National Institute for Uniform Licensing of Power Engineers and its member jurisdictions. It is aimed at people who operate or maintain low-pressure heating plants, small steam or hot water boilers, and related auxiliary equipment under supervision, and at those building a pathway toward higher classes. The NIULPE 4th Class study guide has 10 sections and about 2,481 words.
01Boilers and Boiler Fittings
This domain tests how a Fourth Class candidate identifies boiler types and the fittings that protect and control them. Expect questions on firetube and watertube construction, safety valves, gauge glasses, low-water fuel cutoffs, pressure gauges, feedwater and blowdown piping, and required markings.
294 words, about 1 min02Boiler Operation, Combustion, and Controls
This domain examines safe startup, normal operation, shutdown, fuel/air control, purge and light-off interlocks, flame detection, drum level control, and pressure or temperature limits. Fourth Class questions often ask what a control does and what happens when it fails.
277 words, about 1 min03Pressure Vessels, Piping, Valves, and Safety Devices
This domain covers pressure-vessel protection, piping layout, valve selection, expansion and support, and safety devices. Questions often compare relief valves, safety valves, and rupture discs, or ask why piping needs flexibility.
264 words, about 1 min04Pumps, Compressors, and Auxiliary Equipment
This domain tests centrifugal and positive-displacement pumps, compressors, receivers, traps, filters, and the operating limits that protect them. Expect NPSH, cavitation, affinity laws, intercooling, and safety-valve questions.
238 words, about 1 min05Steam and Hot Water Heating Systems
This domain covers steam traps, condensate return, air venting, piping arrangement, hot-water circulation, expansion tanks, air elimination, and balancing. The exam tests how systems remove air and condensate and how they control temperature and pressure.
261 words, about 1 min06Refrigeration and Air Conditioning
This domain tests the vapor-compression cycle, refrigerant states, metering devices, superheat and subcooling, airflow, and basic psychrometrics. Fourth Class questions focus on identifying components and diagnosing abnormal operation.
222 words, about 1 min07Electrical Systems and Controls
This domain covers motors, starters, overloads, fuses, breakers, grounding, control circuits, sensors, transmitters, and basic PID control. The exam tests safe isolation and how a signal becomes a control action.
230 words, about 1 min08Water Treatment and Chemistry
This domain tests scale, corrosion, carryover, blowdown, softening, deaeration, oxygen scavenging, pH, alkalinity, conductivity, and internal treatment. The exam asks why a treatment is used and how it is controlled.
213 words, about 1 min09Fuels, Combustion, and Environmental Controls
This domain covers fuel properties, combustion calculations, excess air, stack losses, and emissions controls. Expect questions on heating value, viscosity, flash point, sulfur, NOx, CO, and opacity.
247 words, about 1 min10Codes, Regulations, and Safety Practices
This domain tests code jurisdiction, inspection, permits, lockout/tagout, confined-space entry, hot work, incident reporting, and environmental compliance. Fourth Class candidates must know when a task requires authorization and documentation.
235 words, about 1 min