Formula & worked example
x=(hf,high−hf,low)/hfg,low; mflash=x·mcond.
Saturated condensate let down from a higher pressure flashes because its inlet liquid enthalpy exceeds the lower-pressure saturated-liquid enthalpy.
HVAC & plant engineering calculator · Updated Sep 17, 2026
Flash Steam Calculator — Condensate Letdown, Flash % & Recovery
Estimate flash-steam fraction when saturated condensate drops to a lower pressure, plus flash flow, remaining condensate and recoverable flash energy using an explicit enthalpy-property approximation.
Inputs
Live engineering result
Approx. high-side saturation 153.09057 °C
Approx. low-side saturation 99.970951 °C
Flash fraction 9.8168643%
Flash steam flow 98.168643 kg/h
Remaining condensate 901.83136 kg/h
Flash latent-energy rate 61.766307 kW
Assumptions & limits
- Uses compact saturation-property correlations for screening calculations, not an IAPWS property package.
- Final flash-vessel and two-phase piping design should use verified steam tables and applicable pressure-vessel/piping rules.
Frequently asked questions
What does this Flash Steam Calculator calculate?
Estimate flash-steam fraction when saturated condensate drops to a lower pressure, plus flash flow, remaining condensate and recoverable flash energy using an explicit enthalpy-property approximation.
Can I use this for final design?
Use it as an auditable engineering sizing cross-check. Final equipment and piping selections should use project design conditions, manufacturer data, applicable standards and local code.
Why are the engineering assumptions shown?
Plant calculations are sensitive to fluid properties, pressure, temperature and operating hours. Exposing assumptions makes the result easier to verify instead of hiding them behind a single answer.