Note:

This formula calculates the minimum orifice area required for liquids under relieving conditions. It is primarily used in safety valve sizing to ensure the proper discharge of pressurized liquids.

Explanation of Parameters:

• Mass Flow Rate (ṁ): The amount of liquid flowing per hour (kg/h).
• Derated Coefficient of Discharge (Kdr): A correction factor that accounts for valve efficiency.
• Viscosity Correction Factor (Kv): Adjusts for the liquid's viscosity effects on flow.
• Relieving Pressure (P₀): The absolute pressure at which the liquid is relieved (bar a).
• Back Pressure (Pᵦ): The pressure downstream of the valve (bar a).
• Specific Volume (ν): The volume occupied by 1 kg of liquid at the relieving pressure and temperature (m³/kg).
• Constant Value (1.61): A derived factor used in liquid flow calculations to ensure accurate orifice area determination.

BS EN 4126 is a European standard that specifies the design and requirements for safety relief valves used to protect pressurized liquid systems by safely discharging excess fluid, preventing overpressure, and ensuring system safety.

Real-life Applications:

• BS EN 4126 Valves: Ensures safety relief valves are properly sized for liquid discharge.
• Hydraulic Systems: Prevents excess pressure buildup in hydraulic lines.
• Boilers & Steam Systems: Ensures safe liquid discharge before vaporization.
• Fire Safety: Used in fire suppression systems that rely on liquid pressure control.
• Oil & Chemical Processing: Helps in regulating fluid discharge in refineries and chemical plants.

Conclusion:

This calculation ensures that pressurized liquids can be safely discharged, preventing pipe bursts, tank overpressure, and system failure, ultimately enhancing safety and efficiency in industrial operations.