This simulator models an open-reservoir transfer rig — source reservoir, suction strainer, compound suction gauge, pump, discharge gauge, check valve and elevated delivery tank — to show how gauge and absolute pressure references, pipe velocity and vapor-pressure margin combine on both sides of a pump. Change source elevation, resistance coefficients, bore sizes, atmospheric pressure and vapor pressure, and watch suction/discharge pressures and the available margin above vapor pressure update live.
• A real-time 3D cutaway workbench (open source reservoir and free surface, suction strainer and inlet line, compound suction gauge and tap, transfer pump/motor skid, discharge gauge and check valve, elevated receiving tank/riser, and a paired pressure/velocity recorder) with home view, focus-selected-part, show full enclosure, exploded view, auto-rotate, expand and hide-labels scene tools. • Experiment controls: motor speed demand (600–2,200 rpm), motor energized checkbox, source surface elevation above/below pump datum, delivery surface elevation above datum, suction and discharge resistance coefficients, suction and discharge bore, atmospheric absolute pressure and liquid vapor pressure sliders, plus pause/resume, single-step and 1 s-step buttons and four playback speeds. • A Curves & measurements analysis tab with two live charts (suction/discharge gauge pressure; suction absolute pressure), the underlying absolute/gauge-pressure and NPSHa equations, and snapshot readouts (flow, suction/discharge gauge and absolute pressure, suction/discharge head loss, suction/discharge velocity, available suction head above vapor, and a suction-remains-above-vapor validity flag). • An Experiments tab with four guided fixtures (flooded suction, raised source, restricted suction, low atmospheric pressure) and a Model verification bench with a timestamped event log and copyable trial report. • A Learn & assess tab with four guided lessons, a knowledge-check quiz with reset, and a written model-scope statement linking to a DOE pump reference.
The suction gauge reads pressure relative to local atmosphere, so a negative gauge reading (common on the suction side of a pump above its source) does not necessarily mean negative absolute pressure — it simply means the absolute pressure is below atmospheric. The simulator separately tracks gauge pressure (Pgauge = Pabsolute − Patm) and absolute pressure (Ps,abs = Patm + ρg[zs − Ks·Q² − vs²/(2g)]) at both stations, so raising the source above the pump improves absolute inlet pressure even while gauge readings stay in a familiar range.
Available NPSH-style margin, NPSHa = (Patm − Pvapor)/(ρg) + zs − Ks·Q², shrinks whenever atmospheric pressure drops, suction losses rise, or the source is lowered relative to the pump — the restricted-suction and low-atmospheric-pressure experiments isolate each effect. If predicted suction pressure reaches vapor pressure, the model flags this as outside its single-phase envelope rather than modeling the two-phase flow that would actually occur.
This is a synthetic quadratic pump/system model with quasi-steady incompressible flow, a first-order 0.8 s motor speed response, and both pressure taps assumed at the pump datum. Pipe bore changes alter tap velocity head; resistance coefficients are independently imposed rather than derived from bore. Cavitation degradation itself is not modeled in this lab — see the dedicated Cavitation and NPSH simulators for that behavior.
No. Gauge pressure is measured relative to local atmospheric pressure, while absolute pressure is measured relative to a vacuum. A pump's suction side commonly reads negative gauge pressure while its absolute pressure remains well above zero — you add atmospheric pressure to gauge pressure to get absolute pressure.
It omits the velocity-head and elevation differences between the two measurement taps. If the suction and discharge bores differ, their velocities differ too, so total pump head requires the full head balance the simulator computes, not just a raw pressure subtraction.
Raising the source reservoir above the pump increases the static contribution to inlet pressure, improving both the suction gauge reading and the available margin above vapor pressure. Lowering it below the pump has the opposite effect, as shown in the raised-source experiment.
The simulator flags this condition as outside its valid single-phase modeling range — in reality the liquid would begin to vaporize (cavitate). This rig does not model that two-phase behavior; the dedicated Cavitation simulator addresses vapor formation and collapse directly.