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The Weymouth Equation gives more conservative results than the Panhandle equations, and is hence more frequently In Imperial units, the Weymouth equation is

Tsc and Psc are the temperature and pressure at standard conditions, in absolute Fahrenheit Tm is the average temperature of the gas line, in absolute Fahrenheit P1 and P2 are the pressures at the pipe entrance and exit, in absolute psi L is the length of the pipe, in miles G is the relative gas density with respect to air Z is the gas compressibility E is the pipeline efficiency Le is the effective length of the pipeline Δz is the elevation of the pipe exit with respect to the entrance in feet Q is the flowrate, in standard cubic feet per day The gas compressibility Z and density are calculated at an average pressure and temperature, defined below.

The equations given above use several empirical factors, and normally the input parameters would need to be specif

For dry gas fields, the pipeline efficiency is generally around 0.92, casing-head gas would have a pieline efficiency o

uations, and is hence more frequently used. It is valid for steady-state adiabatic (isothermal) flow. The version of the Weymouth equation used in th

solute Fahrenheit

d temperature, defined below.

t parameters would need to be specified in specific units. However, I've programmed the spreadsheet to handle the unit conversions for you. You sim

gas would have a pieline efficiency of 0.77, while gas and condensate pipes have an efficiency of 0.66

of the Weymouth equation used in this spreadsheet also accounts for elevation differences between the pipe entrance and exit.

e the unit conversions for you. You simply specify the input units using drop-down menus.

entrance and exit.

The Weymouth Equation For more engineering spreadsheets go to http://excelcalculations.blogspot.com Parameters Inlet pressure (absolute) Outlet pressure (absolute) Pressure, std condition (absolute) Temperature std condition (absolute) Mean temperature of line (absolute) Inside diameter Pipe length Gas relative density (air=1) Mean gas compressibility Pipeline efficiency Mean gas viscosity Elevation of exit above entrance Result Flowrate (std conditions)

1000 946.2 14.7 520 530 17.5 20 0.6 0.85 0.95 1 400

1.3136E+08

Pressure units

psia Pa

Inlet pressure Outlet pressure Pressure, std condition Temperature std condition Mean temperature of line Inside diameter Pipe length Gas relative density (air=1) Mean gas compressibility Pipeline efficiency Pipe effective roughness Mean gas viscosity s Le

Weymouth equation

Temperature Units

Length units

Viscosity

Volume flowrate

F K

in m miles

Pa s cP

ft^3/day m^3/s

std condition ure std condition mperature of line

Unit 1 1 1 1 1 1 3

Value in Imperial 1000 946.2 14.7 520 530 17.5 20

ve density (air=1) compressibility

tive roughness viscosity

h equation

2 1

1 0.0016648169 20.0166574113 131355536.113474

1

1.3236E+08

451