Steam Pipes  Online Pressure drop Calculator
Calculate pressure drops in steam distribution pipe lines.
The pressure drop in a saturated steam distribution pipe line can be calculated in metric units as
dp = 0.6753 10^{6} q^{2} l (1 + 91.4/d) / ρ d^{5 }(1)
where
dp = pressure drop (Pa)
q = steam flow rate (kg/h)
l = length of pipe (m)
d = pipe inside diameter (mm)
ρ = steam density (kg/m^{3})
The Unwin formula can also be expressed in imperial units as
dp = 0.0001306 q^{2} l (1 + 3.6/d) / (3600 ρ d^{5})^{ }(2)
where
dp = pressure drop (psi)
q = steam flow rate (lb/hr)
l = length of pipe (ft)
d = pipe inside diameter (inches)
ρ = steam density (lb/ft^{3})
Use values for the specific volume corresponding to the average pressure if the pressure drop exceeds 10  15 % of the initial absolute pressure.
Note that for elevated velocities the Unwin's formula is known to give pressure drops higher than the actual.
Example  Pressure Drop in a Steam Pipe
A steam flow 4000 kg/h with pressure 10 bar (1000 kPa) and density 5.15 kg/m^{3} flows through a schedule 40 ND 100 steel pipe with inside diameter 102 mm and length 100 m. The pressure drop can be calculated as
dp = 0.6753 10^{6} (4000 kg/h)^{2} (100 m) (1 + 91.4/(102 mm)) / ((5.15 kg/m^{3}) (102 mm)^{5 } )
= 36030 Pa
= 36 kPa
Steam Pressure Drop Calculator  Metric Units
Steam Pressure Drop Calculator  Imperial Units
Pressure Drop Diagrams  metric units
The diagrams below can be used to indicate pressure drop in steam pipes at different pressures. The calculations are made for schedule 40 pipe.
 1 bar = 100 kPa = 10,197 kp/m^{2} = 10.20 m H_{2}O = 0.9869 atm = 14.50 psi (lb_{f}/in^{2})
 1 kg/h = 2.778x10^{4} kg/s = 3.67x10^{2} lb/min
Steam  pressure 1 bar gauge
Steam  pressure 3 bar gauge
Steam  pressure 7 bar gauge
Steam  pressure 10 bar gauge
Related Topics

Pipe Sizing
Sizing of steam and condensate pipe lines  pressure loss, recommended velocity, capacity and more. 
Steam and Condensate
Steam & condensate systems properties, capacities, pipe sizing, systems configuration and more.
Related Documents

ASME/ANSI B36.10/19  Carbon, Alloy and Stainless Steel Pipes  Dimensions  Metric Units
Pipe sizes, inside and outside diameters, wall thickness, schedules, weight and weight of pipe filled with water  Metric Units. 
Pressure
Introduction to pressure  online pressure units converter. 
Properties of Saturated Steam  SI Units
Saturated Steam Table with steam properties as specific volume, density, specific enthalpy and specific entropy. 
Recommended Velocities in Steam Systems
The steam velocity in a steam distribution system should be within certain limits to avoid excessive wear and tear 
Saturated Steam  Properties  Imperial Units
Steam table with sensible, latent and total heat, and specific volume at different gauge pressures and temperatures. 
Saturated Steam  Properties for Pressure in Bar
Saturated Steam Table with properties like boiling point, specific volume, density, specific enthalpy, specific heat and latent heat of vaporization. 
Sizing of Steam Pipes (kg/h)
Steam is a compressible gas where pipe line mass flow capacity depends on steam pressure. 
Sizing of Steam Pipes (lb/h)
Steam is a compressible gas where the capacity of a pipe line depends on the size of the pipe and the steam pressure. 
Steam & Condensate Equations
Steam consumption and condensate generation when heating liquid or gas flows 
Steam Flow  Orifices
Steam flow through orifices  for steam pressures ranging 2  300 psi 
Steam Flow Rate vs. Pressure Drop  Schedule 40 Pipe
Flow rate (lb/h) and pressure drop per 100 feet of pipe. 
Steam Heating Systems  Design
An introduction to the basic design of steam heating systems. 
Steam Pipes  Max. Flow and Pressure Drop
Pressure drop and maximum allowable flow in steam pipes. 
Steam Pipes  Pressure Drop vs. Steam Flow
Steam pipes and pressure drop diagrams  imperial and metric units. 
Steam Pipes  Sizing
Sizing of steam pipe lines  major and minor loss in steam distribution systems.