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PE Mechanical · Thermal & Fluid Systems

Fluid Equipment and Distribution Systems

17–26 of 80

Area title, subtopics, and question range per the NCEES specification (eff. October 2025).

What's in this area

  • Piping Components and Connections
  • Fluid Distribution Systems
  • Pumps and Fans
  • Compressors, Nozzles, and Diffusers

Moving fluid through systems and the machines that move it: piping components and connections, fluid distribution systems, pumps and fans, and compressors/nozzles/diffusers. One of the heavier areas on the Thermal & Fluid Systems depth.

What the problems look like

Pressure-drop and machine-performance calculations — pipe pressure drop (Darcy, minor losses, series/parallel) and system curves; pump/fan operating point, NPSH, affinity laws, and power; compressors/nozzles/diffusers (isentropic relations, nozzle exit velocity, choked flow). Exhibit-rich (system and pump curves) and frequently multi-step.

By exam day you should be able to —

  • compute pipe pressure drop — Darcy-Weisbach, friction factor (Moody), minor losses (K), series/parallel pipes;
  • find a pump/fan operating point on the system curve; check NPSH available vs. required; apply the affinity laws; compute hydraulic vs. brake power;
  • work compressors/nozzles/diffusers — isentropic relations, nozzle exit velocity, choked flow.

Where people lose points

  • Darcy vs. Fanning friction factor (a 4× difference).
  • Pump hydraulic vs. brake power — BHP = hydraulic power ÷ η.
  • NPSH available vs. required — cavitation when available < required; and the sign on suction lift (z is subtracted when the source sits below the pump: NPSH_a = (P_atm − P_vap)/γ ± z − h_f).
  • Affinity-law exponents (Q ∝ N, H ∝ N², P ∝ N³).
  • Minor-loss K applied to the wrong velocity head.
  • Choked flow — once at the critical pressure ratio (Mach 1 at the throat), lowering downstream pressure doesn't raise flow.

Have these at your fingertips

Darcy h_f = f(L/D)(V²/2g), the Moody chart, NPSH, and the affinity laws — plus where they sit in the Handbook.

Going deeper

Part of the Thermal & Fluid Systems depth. Practice this area with exam-real problems — the tutor walks any one you miss. → Start your 7-day free trial — no card. Or take the free practice exam first.