This calculator is primarily intended for calculating flow rate through a hydraulic orifice for incompressible fluids. By entering the orifice diameter, pressure drop, discharge coefficient, and fluid specific gravity, the tool instantly computes flow using standard orifice flow equations in SI units. It is well-suited for quick sizing checks, performance estimates, and comparison of different orifice designs. All inputs and results use SI units.
Hydraulic Orifice Calculator – SI Units
m³/s→L/min*60000. Comma or dot accepted.
How to Use This Calculator
1. Enter fluid and orifice properties
Enter the discharge coefficient (C) for the orifice geometry. Typical values are shown below the input field.
Enter the fluid specific gravity (SG). Density is calculated internally as ρ = 1000 × SG (kg/m³).
2. Select what you want to calculate
Use the “Calculate for” dropdown to choose Flow (Q), Pressure drop (ΔP), or Diameter (d). The required input fields update automatically.
3. Enter the known values
Depending on the selected mode, enter diameter (mm), pressure drop (bar), or flow rate (L/min). Decimal comma or dot notation is accepted.
4. Read the result
The calculated value is displayed immediately below the input fields. The equation used is shown above for reference.
Notes:
This tool assumes steady, incompressible flow and does not account for pipe losses, fittings, or elevation changes.
Results are intended for engineering estimation and sizing. For critical applications, results should be verified against standards or detailed hydraulic analysis.
Specific Gravities of Common Fluids
| Fluid | Specific Gravity | Notes |
|---|---|---|
| Water | 1,000 | Reference standard |
| Hydraulic oil VG 46 | 0,870–0,880 | Base oil and additive dependent |
| Diesel fuel | 0,820–0,850 | Varies by blend and temperature |
| Gasoline (petrol) | 0,720–0,780 | Lower SG → higher volatility |
| Kerosene (Jet A-1) | 0,800–0,815 | Common aviation fuel |
| Engine oil (SAE 10W-40) | 0,860–0,890 | Depends on formulation |
| Gear oil (SAE 80W-90) | 0,880–0,910 | Higher due to additives |
| Brake fluid (DOT 4) | 1,040–1,080 | Glycol-based |
| Coolant (ethylene glycol 50%) | 1,070–1,080 | Water mix dependent |
| Transmission fluid (ATF) | 0,830–0,870 | Similar to light hydraulic oil |
| Crude oil (light) | 0,790–0,850 | Highly variable |
| Seawater | 1,025 | Salinity ≈ 35 ppt |
| Milk | 1,028–1,035 | Slightly denser than water |
| Mercury | 13,534 | Very dense metal |
Approximate Orifice Coefficients
| Description | L/D | r/D | C |
|---|---|---|---|
| Sharp-edged orifice (thin plate) | 0 | 0,00–0,05 | 0,61 |
| Round-edged orifice (fully rounded) | 0 | 0,15–0,25 | 0,98 |
| Short tube — separation | 0,25–0,50 | 0,00–0,05 | 0,61 |
| Short tube — no separation | 0,50–1,00 | 0,05–0,10 | 0,80 |
| Short tube with rounded entrance | 0,50–1,00 | 0,15–0,25 | 0,97 |
| Reentrant (Borda) tube, length < 0,5D | <0,50 | 0 | 0,54 |
| Reentrant tube, length 2–3D | 2,00–3,00 | 0 | 0,72 |
| Borda mouthpiece (classic reentrant) | ≈1,00 | 0 | 0,51 |
| Smooth, well-tapered nozzle | 2,00–5,00 | — | 0,98 |