Mod 2 - PD Pumps

Module from the Rotating Equipment Training Curriculum curriculum.

POSITIVE DISPLACEMENT PUMPS · Learning Objectives · 1. Compare reciprocating, rotary, and diaphragm PD pump types 2. Understand pulsation dampening and acceleration head requirements 3. Select PD pump type based on flow, pressure, and fluid properties 4. Calculate displacement and volumetric efficiency · PD Pump Type Comparison

Type	Principle	Max Pressure (psig)	Max Flow (GPM)	Viscosity Range	Best Application	Limitations
Piston/Plunger	Reciprocating displacement in cylinder	10,000+	500	Low-medium	High-pressure injection, chemical dosing, BFW	Pulsating flow, check valve maintenance
Diaphragm	Flexing membrane, no shaft seal	150 (air) / 1500 (hydraulic)	300	Any (non-settling)	Corrosive/toxic fluids, slurries, metering	Limited pressure (air), diaphragm life
External Gear	Two meshing gears trap fluid	3,000	200	10-100,000 cSt	Lube oil, fuel oil, viscous fluids	Wear with abrasives, not for low viscosity
Internal Gear	Gear-within-gear, crescent seal	200	600	10-1,000,000 cSt	Very viscous fluids, chocolate, polymers	Lower pressure capability
Screw (twin/triple)	Intermeshing screws trap fluid	1,500	5,000	1-1,000,000 cSt	Crude oil transfer, fuel oil, lube systems	Cost, alignment sensitivity
Peristaltic/Hose	Roller compresses flexible hose	250	200	Any	Lab dosing, corrosive, shear-sensitive fluids	Hose replacement, low pressure
Lobe	Two counter-rotating lobes	200	3,000	1-1,000,000 cSt	Food/pharma, sludge, low-shear transfer	Lower efficiency, timing gear maintenance
Progressive Cavity	Rotor in stator (helical displacement)	1,500	2,000	1-1,000,000 cSt	High-viscosity, abrasive slurries, wastewater	Stator wear, no dry running
Source: FOS Chief Files — Compressor & Pump folder, Starting reciprocating pumps under load.pdf, Metering pump cross section.pdf

Source: Rotating_Equipment_Training_Curriculum_v1.xlsx · Sheet: Mod 2 - PD Pumps

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