ChemTools

API 520 Relief Valve Sizing

Pressure Relief Tool

The Pressure Relief Tool is a professional API 520 sizing and verification application for engineers. It performs gas, liquid and steam relief calculations, integrates thermodynamic property estimation using the Peng–Robinson equation of state and IAPWS steam tables, and provides comprehensive reporting suitable for review.

Available on Google Play

Designed for process engineers working in the office or in the field.

Coming Soon!

01

Define the Relief Scenario

Enter relieving pressures, temperatures, flow rate and factors/coefficients using an interface designed specifically for engineers

02

Build the Process Fluid

Select pure components or define complex mixtures. Thermodynamic properties are calculated automatically using the Peng–Robinson equation of state

03

Calculate Relief Requirements

Determine required orifice area, flow regime, downstream temperature and API sizing with one tap.

What’s Included

Relief Modes

  • ✔ Gas / Vapour Relief
  • ✔ Liquid Relief
  • ✔ Steam Relief
  • ○ Two-phase relief sizing – Coming Soon

Thermodynamics

  • ✔ Peng–Robinson Equation of State
  • ✔ IAPWS-IF97 Steam Properties
  • ✔ 432 Compound Database
  • ✔ User-defined physical properties

Outputs

  • ✔ API 526 orifice sizing
  • ✔ Compressibility factor
  • ✔ Joule–Thomson cooling
  • ✔ Two-phase condition detection
  • ✔ Export and share reports

General

  • ✔ SI & Imperial Units
  • ✔ Offline operation
  • ✔ Flow area & rating mode

Engineering Notes

  • Two-phase relief sizing is not currently implemented
  • Flashing calculations assume isenthalpic expansion
  • Physical property correlation equations and parameters are from the ChemSep database
  • Peng–Robinson binary interaction parameters are based on the ChemSep dataset
  • Atmospheric pressure is taken to be 101.325 kPa

Version History

A concise record of updates to the Pressure Relief Tool. Only meaningful engineering changes are listed.

  • v1.0.0 — Initial release. Includes relief valve sizing, report generation and sharing, unit conversions, and offline operation.

Future updates will be documented here as new tools and features are released.

Get the App

Ready to simplify pressure relief calculations?

Coming Soon!

Engineering Notice: Pressure Relief Tool is intended for use by competent engineering professionals. Users are responsible for independently reviewing all calculations before applying them in practice.