This simulator connects two redundant pumps to one receiving vessel through a single shared outlet valve. It lets you fail the pumps or the valve by hand, then switch to independent outlet paths to see how much reliability the common valve was costing.
• A 3D view of two pump branches, a shared outlet valve, independent outlet paths and a receiving vessel. • Sliders for mission duration (100-3000 h), component failure rate (0.05-2 per 1000 h) and shared-valve failure rate (0.05-2 per 1000 h), switches to fail pump A, pump B or the common valve, and an independent-outlet-paths switch. • Four live readouts: mission service survival, shared-valve survival, live flow delivered and the reliability loss from the common valve. • Two presets: Shared valve fails (both healthy pumps are unable to deliver) and Remove shared dependency (an independent outlet delivers despite the excluded valve fault).
With pump survival Rp and valve survival Rv, the shared arrangement gives R_shared = Rv [1 - (1 - Rp)^2], a product of the valve with the parallel pump pair. With independent outlet paths the valve is no longer in series and R_independent = 1 - (1 - Rp)^2. The difference is the reliability loss caused by the common valve, which is a single point of failure because its loss disables everything downstream.
Pump and valve mission probabilities are independent. The separate-path comparison assumes ideal extra piping and valves, so it omits the failure modes of that additional hardware. In separate-path mode, manually failing the excluded common valve has no effect. In a real design you would examine the reliability of any bypass or second path as well.
No. If both pumps discharge through one common valve, that valve remains a single point of failure and its loss stops all flow.
R_shared = Rv x [1 - (1 - Rp)^2]: the pump pair is redundant, but the valve is in series with it.
Yes. The teaching comparison assumes ideal extra piping and valves, but real separate paths add their own failure modes that must be analyzed.
It excludes repair, valve-specific failure modes and the reliability of the additional piping used in the separate-path case.