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# Steam Pipes - Online Pressure drop Calculator

The pressure drop in a saturated steam distribution pipe line can be calculated in metric units as

dp = 0.6753 106 q2 l (1 + 91.4/d) / ρ d5                                           (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/m3)

The Unwin formula can also be expressed in imperial units as

dp = 0.0001306 q2 l (1 + 3.6/d) / (3600 ρ d5)                                                  (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/ft3)

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/m3 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 106  (4000 kg/h)2  (100 m) (1 + 91.4/(102 mm)) / ((5.15 kg/m3)  (102 mm)5 )

= 36030 Pa

= 36 kPa

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### Steam Pressure Drop Calculator - Imperial Units

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#### 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/m2 = 10.20 m H2O = 0.9869 atm = 14.50 psi (lbf/in2)
• 1 kg/h = 2.778x10-4 kg/s = 3.67x10-2 lb/min

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## Related Topics

### • Sizing of Steam and Condensate Pipes

Dimensions of steam and condensate pipe lines. Calculate pressure losses, recommended velocities, capacities and more.

### • Steam and Condensate

Design of steam & condensate systems with properties, capacities, sizing of pipe lines, system 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 Steam Pipes (kg/h)

Steam is a compressible gas where pipe line mass flow capacity depends on steam pressure.

### Sizing 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.

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