Flagship-depth build from the OneDrive VS_xx series (gas-load budget VS_02, conductance networks VS_03) plus the master equation reference. Molecular-flow formulas; for transitional/viscous regimes apply regime corrections.
Gas-Load Budget → Required Pump Speed
P_ss=Q_total/S_net. Sum outgassing (q×A) + leaks; size the pump for a target pressure. q values at 1 h, industry reference (CERN / Jousten).
Conductance & Pumping Network
Tube C=12.3·d³/ℓ, orifice C=11.6·D² (cm, molecular flow). Series 1/C=Σ1/Cᵢ; net speed 1/S_net=1/S_pump+1/C.
Two-Stage Pump-Down
Roughing t₁=(V/S_r)ln(P_atm/P_x), then high-vac t₂=(V/S_net)ln(P_x/P_target). Curve overlays both stages + outgassing floor.
Mean Free Path & Knudsen
λ=k_BT/(√2πd²P); Kn=λ/L → flow regime.
Rate-of-Rise Leak Test
Q=(dP/dt)·V; isolate pump, measure rise.
Paschen Breakdown (air)
V_b=B·pd/[ln(A·pd)−ln(ln(1+1/γ))].
Formula reference & outgassing data
P=Q/S_net, 1/S_net=1/S_pump+1/C; tube C=12.3d³/ℓ, orifice C=11.6D² (cm); series 1/C=Σ1/Cᵢ, parallel ΣCᵢ; elbow ×0.85.
Pump-down t=(V/S)ln(P₀/P); λ=k_BT/√2πd²P; Kn=λ/L. q@1h (Pa·m³/s/cm²): SS degreased 2e-10, EP-SS 5e-11, SS baked 2e-14, Al 3e-11, Cu 1e-11, Viton 5e-7, Kapton 3e-12, PEEK 5e-12.
Lesson (VS_02): elastomer O-rings dominate the UHV gas budget — CF flanges are not optional below ~10⁻⁶ Pa.