Fired Heater Learning Center

Pressure Drop & Inside Film Coefficient Calculator

Pressure Drop & Inside Film Coefficient Calculator

This calculator allows the user to input the average fluid temperature, pressure, percent vapor, flow rate, pipe size, number of passes, and the necessary fluid properties. The calculator then determines the velocity, the Reynolds number, the Fanning friction factor, the pipe friction factor,the pipe velocity head and the pipe friction loss in psi.

These correlations may be used for compressible fluids or mixtures, but should be used with caution since average conditions, not actual inlet and outlet properties are being used. In general, if the pressure drop is greater than 40% of the inlet conditions, these equations should not be used. If wall film temperature and viscosity are not known, input bulk properties.

Flow Rate lb/hr: Avg Fluid Press psia:
Bulk Fluid Temp °F: Fluid Temp At Wall °F:
Tube Inside Dia in: Number of Tube Passes:
Tube Length ft:
Film Coef. Method: Percent Vapor %:
Liq Visc At Bulk Temp cp: Liq Visc At Film Temp cp:
Liq Specific Gravity: Liq Specific Heat Btu/lb-°F:
Liq Therm Cond Btu/hr-ft-°F: Vap Viscosity At Bulk cp:
Vap Molecular Weight: Vap Specific Heat Btu/lb-°F:
Vap Therm Cond Btu/hr-ft-°F: Vap Compressibility Factor:


The formulas and correlations presented herein are all in the public domain and are to be used only as a learning tool. Note that any product, process, or technology in this document may be the subject of other intellectual property rights reserved by sponsors or contributors to this site. This publication is provided as is, without any warranty of any kind, either expressed or implied, including, but not limited to, the implied warranties of fitness for a particular purpose, or non-infringement.

The formulas, correlations, and methods presented herein should not be considered as being recommended by or used by the sponsors of this site. The purpose of this site is educational and the methods may or may not be suitable for actual design of equipment. Only a fired heater design engineer is qualified to decide if a calculation or procedure is correct for an application.