Reynolds Number Viscosity Correction

Correct the orifice discharge coefficient for Reynolds number at low-flow, viscous service.

Reynolds number correction

Reynolds number correction is computed deterministically from the parameters encoded in this page's address, so the same inputs always produce the same result and the same OAS-XXXX verification hash.

Viscosity effect on Cv

Viscosity effect on Cv is computed deterministically from the parameters encoded in this page's address, so the same inputs always produce the same result and the same OAS-XXXX verification hash.

Corrected orifice diameter

Corrected orifice diameter is computed deterministically from the parameters encoded in this page's address, so the same inputs always produce the same result and the same OAS-XXXX verification hash.

Engineering summary

Governing parameters and computed results for Reynolds Number Viscosity Correction.

Governing parameters and computed results for this calculation
Parameter Value
Fluid oil

Frequently asked questions

When does gas flow through an orifice become choked?
Gas flow chokes when the downstream-to-upstream absolute pressure ratio falls to or below the critical ratio (2/(k+1))^(k/(k−1)) — about 0.528 for air. Below that ratio the flow is sonic and further downstream pressure reduction adds no flow.
How do I convert between Cv and Kv?
Kv = 0.865 · Cv. Cv is the US gallons-per-minute of water at 60 °F that flows through the restriction at a 1 psi drop; Kv is the metric equivalent in cubic metres per hour at a 1 bar drop.
What discharge coefficient should a sharp-edged orifice use?
A sharp-edged, square-shouldered orifice uses a discharge coefficient near 0.62 for a fully turbulent liquid. The coefficient falls in the laminar regime, which is why a Reynolds-number viscosity correction matters at low flow.