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Steam Trap Safety Factor

Reference data and engineering information about steam trap safety factor for steam and condensate applications.

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Overview

Engineering reference data for Steam Trap Safety Factor in steam condensate.

Key Formulas

Steam Quality

x=mvmtotalx = \frac{m_v}{m_{total}}

Mass fraction of vapor in two-phase mixture.

Enthalpy of Wet Steam

h=hf+xhfgh = h_f + x \cdot h_{fg}

Specific enthalpy of wet steam.

Flash Steam

mflash=mliquidhfhf2hfg2m_{flash} = m_{liquid} \frac{h_f - h_{f2}}{h_{fg2}}

Steam generated when condensate flashes to lower pressure.

Condensate Load

mc=Qhfgm_c = \frac{Q}{h_{fg}}

Condensate generated by heat transfer.

Variables

SymbolDescriptionUnit
xxSteam quality
hfh_fEnthalpy of saturated liquidkJ/kg
hfgh_{fg}Latent heat of vaporizationkJ/kg
hhSpecific enthalpykJ/kg
QQHeat transfer ratekW

Steam Trap Safety Factor Table

6 rows
Recommended safety factors for sizing steam traps to handle startup condensate loads.
Steam Trap Type
Safety Factor
Balanced Thermostatic Steam Trap3
Bimetallic Steam Trap2.5
Float Steam Trap2
Inverted Bucket Steam Trap2.5
Liquid Expansion Steam Trap3
Thermodynamic Steam Trap1.5

Source: engineeringtoolbox.com

Sizing Principle

A steam trap must be properly sized to handle the full load of condensate during startup. The safety factor is a multiplier applied to the estimated condensate load to ensure the trap has sufficient capacity.

Application Formula: Qtrap=Qcondensate×Safety FactorQ_{trap} = Q_{condensate} \times \text{Safety Factor}

Where:

  • QtrapQ_{trap} is the required trap capacity (kg/h or lb/h).
  • QcondensateQ_{condensate} is the estimated maximum condensate load during operation or startup.

References