Safety Valves Gas Vapor

Overview

Engineering reference data for Safety Valves Gas Vapor in fluid mechanics.

Key Formulas

Reynolds Number

$Re = \frac{\rho v D}{\mu}$

Ratio of inertial to viscous forces — determines flow regime.

Bernoulli's Equation

$P + \frac{1}{2}\rho v^2 + \rho g h = \text{const}$

Conservation of energy for steady, inviscid, incompressible flow.

Continuity Equation

$A_1 v_1 = A_2 v_2$

Conservation of mass for incompressible flow.

Darcy-Weisbach

$\Delta P = f \frac{L}{D} \frac{\rho v^2}{2}$

Pressure drop due to friction in a pipe.

Variables

Symbol	Description	Unit
$Re$	Reynolds number	—
$\rho$	Fluid density	kg/m³
$v$	Flow velocity	m/s
$D$	Characteristic dimension	m
$\mu$	Dynamic viscosity	Pa·s
$P$	Pressure	Pa
$f$	Darcy friction factor	—

Gas Safety Valve Coefficient Table

The coefficient C is determined from the ratio of specific heats for the gas and is used in both the mass flow (lb/hr) and volumetric flow (SCFM) discharge area calculations.

Discharge Coefficient Reference

The discharge coefficient $k_d$ accounts for the efficiency of the valve design:

Valve Type	Typical $k_d$
Standard safety valve	0.975

The back pressure coefficient $k_{bp}$ equals *1.0 for atmospheric discharge systems. For balanced bellows or pilot-operated valves, consult manufacturer data for specific $k_{bp}$ values at elevated back pressures.

Interactive Charts

References

• Original Source