Calculator Inputs
Formula Used
- K-factor method: Flow (L/s) = f / K, where f is frequency (Hz) and K is pulses per liter.
- Strouhal method: f = St · V / D so V = f · D / St, then Q = V · A and A = πD²/4.
- Reynolds check: Re = ρVD/μ, where ρ is density and μ is dynamic viscosity.
This tool uses simplified relationships for planning and troubleshooting. For billing-grade accuracy, follow your sensor’s calibration sheet.
How to Use
- Select the method that matches your sensor output.
- Enter frequency from your controller or data logger.
- Enter the pipe inner diameter, not the outer size.
- For K-factor, enter pulses per liter from calibration.
- For Strouhal, keep St near 0.2 unless known.
- Review Reynolds status to judge measurement stability.
- Use CSV or PDF export to save irrigation records.
Example Data Table
| Scenario | Method | Frequency (Hz) | Diameter | K-factor / St | Flow (L/min) | Reynolds |
|---|---|---|---|---|---|---|
| Drip mainline check | K-factor | 12.0 | 25 mm | K = 4.0 pulses/L | 180.0 | ~76,000 |
| Sprinkler zone audit | Strouhal | 18.5 | 32 mm | St = 0.20 | ~285.0 | ~145,000 |
| Nutrient loop review | K-factor | 7.5 | 20 mm | K = 5.0 pulses/L | 90.0 | ~47,000 |
Example outputs are illustrative and depend on your exact sensor and pipe details.
Vortex Flow Measurement for Irrigation Loops
Vortex meters infer flow from a shedding frequency created by a bluff body. In irrigation, they help verify zone demand, detect clogged filters, and compare pump performance. Stable readings require a steady upstream profile, a full pipe, and a sensor matched to the expected flow band. Frequency output is robust for long cable runs, making it practical for remote garden controllers and data loggers.
Choosing Inputs That Match Field Hardware
If your transmitter provides pulses per liter, the K-factor method converts frequency directly to volumetric flow. If you know pipe diameter and an approximate Strouhal number, the Strouhal method estimates velocity then multiplies by cross‑sectional area. Use inner diameter, not nominal size, because wall thickness changes area significantly. For plastic irrigation pipe, check the actual inside dimension from the manufacturer table.
Reynolds Number as a Quality Check
Reynolds number relates inertia to viscosity and indicates whether turbulence is strong enough for consistent vortex formation. Water at 20–25°C is near 1 cP, but nutrient concentrates or chilled water can raise viscosity and lower Reynolds. When Reynolds is low, expect drift, noisy totals, or a threshold where flow appears to drop out. If results fluctuate, verify sensor grounding, remove bubbles, and test at higher flow to push Reynolds upward for steadier totals.
Installation Details That Improve Accuracy
Place the meter after straight pipe where possible and avoid immediately upstream elbows, tees, or throttling valves. Keep air out with proper venting and avoid running partially full pipes in sloped lines. For fertigation, plan flushing so deposits do not change the effective bluff‑body geometry. Add a strainer upstream to protect the sensor.
Using Results for Decisions and Records
Convert the calculated flow to L/min for quick zone balancing, or m³/h for pump curves and energy audits. Compare the same zone over time to spot emitter wear or leaks. Export CSV for spreadsheets and create PDF logs for maintenance, compliance, and seasonal tuning.
FAQs
1) What does this calculator estimate?
It converts vortex frequency into flow rate, then reports velocity and a Reynolds check. Use it for planning, zone auditing, and troubleshooting, not for custody‑transfer billing.
2) When should I choose the K-factor method?
Use it when your meter is calibrated in pulses per liter or pulses per gallon. Enter the published K-factor and your measured frequency for a direct volumetric flow result.
3) What Strouhal number should I enter?
If you do not have a datasheet value, start near 0.20. Small design differences shift Strouhal, so treat this method as an estimate and compare against a bucket test when possible.
4) Why is Reynolds number important here?
Vortex shedding needs sufficiently turbulent flow. Low Reynolds can cause unstable vortices, jumpy readings, or dropouts. The calculator flags a guidance range so you can judge confidence.
5) How can I reduce noisy or drifting readings?
Confirm the pipe is full, remove air pockets, and keep the sensor downstream of straight pipe. Avoid throttling valves right before the meter. Check grounding and shielded wiring if electrical noise is suspected.
6) Can I use nutrient solutions or fertigation water?
Yes, but update viscosity and density if they differ from clean water. Flush lines to prevent deposits on the bluff body. Verify chemical compatibility with seals and the sensor housing.