PIPETULATOR

Mass Flow Rate 5 kg/sPipe Diameter 100 mm

Velocity 0.64 m/sDynamic Pressure 203 paReynolds Number 4.9E+04Roughness 0.046 mmFDash (Alsthul Approx) 0.0228Friction Factor 0.0228Pressure Drop / m 46 pa / m

Fitting K Factor 0.3

Fitting Pressure Drop 60.80912865 pa

Example 1 use of K Factor different Example 2 use of K Factor different

CIRCULAR CIRCULARDUCT Sizing Calc DUCT Sizing Calc

Volume Flow Rate 0.77 m³/s Volume Flow Rate 0.032 m³/s

Hydraulic Diameter 500 mm Hydraulic Diameter 100 mm

Velocity 3.92 m/s Velocity 4.07 m/sDynamic Pressure 9.23 pa Dynamic Pressure 9.96 paReynolds Number 1.1E+05 Reynolds Number 2.3E+04Roughness 0.15 mm Roughness 0.15 mmFDash (Alsthul Approx) 0.0192 FDash (Alsthul Approx) 0.0285Friction Factor 0.0192 Friction Factor 0.0285Pressure Drop 0.35 pa/m Pressure Drop 2.84 pa/m

Pressure loss Factor 0.75Fitting K Factor 0.038359 Fitting K Factor 7.47

Fitting Pressure Drop 3.54 pa Fitting Pressure Drop 9.96 paK Factor K Factor

Note

K Factor = P or alternative K Factor = PD for fittings

______________ X 10 K Factor = AS CIBSE / HVAC CALC GUIDELINESBSRIA Guide 30/2007 page 107

0.6 * v squared or alternative K Factor = PD for fittings

K Factor =is the Pressure loss factorWhere P is the pressure drop

K X Pv where delta P is = to K x 0.5 X P X V squaredand V is the Velocity per metre, squared

where P is eqaul to 1.2 Kg/m density of airMultiply by the Dynamic pressure and again by 10 is by a Factor of experience

This may be reduced or increased depending on Pv = 0.5 X P X V squared.,. TM 23 air leakage requirements,…..but as a general guide 10 is used Where V = velocity in m/s

USE OF THIS K FACTOR ALLOWS NO AIR LEAKAGE, but this may be considered

Example 1 use of K Factor different Example 2 use of K Factor different Exmple 3 - use of K Factor different

DUCT Sizing Calc DUCT Sizing Calc DUCT Sizing Calc

Volume Flow Rate 5.8 m³/s Volume Flow Rate 5.8 m³/s Volume Flow Rate 5.8 m³/sDuct Width 1000 mm Duct Width 1000 mm Duct Width 1000 mmDuct Height 800 mm Duct Height 800 mm Duct Height 800 mm

Hydraulic Diameter 984 mm Hydraulic Diameter 984 mm Hydraulic Diameter 984 mm

Velocity 7.63 m/s Velocity 7.63 m/s Velocity 7.63 m/sDynamic Pressure 34.94 pa Dynamic Pressure 34.94 pa Dynamic Pressure 34.94 paReynolds Number 4.2E+05 Reynolds Number 4.2E+05 Reynolds Number 4.2E+05Roughness 0.15 mm Roughness 0.15 mm Roughness 0.15 mmFDash (Alsthul Approx) 0.0147 FDash (Alsthul Approx) 0.0147 FDash (Alsthul Approx) 0.0147Friction Factor 0.0153 Friction Factor 0.0153 Friction Factor 0.0153Pressure Drop / m 0.54 pa/m Pressure Drop / m 0.54 pa/m Pressure Drop / m 0.54 pa/m

Pressure loss Factor 0.75Fitting K Factor 0.015513 Fitting K Factor s/t 26.20 Fitting K Factor s/t 58.22589

2.97 mm WGFitting Pressure Drop 5.42 pa Fitting Pressure Drop 34.94 pa Fitting Pressure Drop 29.11 pa

Simple Calculation of K FactorAS CIBSE / HVAC CALC GUIDELINES FOR FITTINGS

Note BSRIA Guide 30/2007 page 107 K = V squaredor alternative K Factor = PD for fittings divided by

K Factor = P so E18 2gK Factor = is the Pressure loss factor

______________ X 10 divided by where 2 g isK X Pv where delta P is = to K x 0.5 X P X V squared

0.6 * v squared 0.6 X E12 X E12 2 times Gravity at where P is eqaul to 1.2 Kg/m density of air 9.81 mm WG

then multiplied by Dynamic pressure X factor of 10 Pv = 0.5 X P X V squared.,. Times 9.81 to Where V = velocity in m/s convert to pa

Where P is the pressure drop

and V is the Velocity per metre, squared USE OF THIS K FACTOR ALLOWS NO AIR LEAKAGE, but this may be considered

Multiply by the Dynamic pressure and again by 10 is by a Factor of experienceThis may be reduced or increased depending on TM 23 air leakage requirements,…..but as a general guide 10 is used

Then air velocities ,..may be increassed by a factor of 10% to allow for any subsequent air leakage

Pipe Surface Roughness (CIBSE C4.7)

Material Roughness (mm)

Non-ferrous drawn piping 0.0015 Doosan Babcock Reference SheetPlastic piping 0.003Asbestos cement piping 0.013 = DATA to ,..INPUT OUTPUT / ANSWER

Black steel piping (new) 0.046 DUCT SIZING Calculation SheetBlack steel piping (rusted) 2.5 EXAMPLE Type 1

Properties of Water

Temperature (°C) 10 DUCT Sizingdensity (kg/m³) 999.73 Prepared: Date:dynamic viscosity (Pa/m) 0.00131 CDB 2/4/2010 Volume Flow Rate 0.064 m³/s

kinematic viscosity (m²/s) 1.306E-06 Duct Width 150 mm3. Assumptions Duct Height 150 mm

Duct Surface Roughness (CIBSE C4.7) a) Assumed data Hydraulic Diameter 165 mm

Material Roughness (mm)

steel 0.15 Velocity 2.99 m/sneat cement/plaster 0.25 Dynamic Pressure 5.35 paspiral wound galvanised 0.075 The flow rate into the rooms are a combination of mechanical ventilation and cascaded air. Reynolds Number 2.7E+04sheet aluminium 0.05 Roughness 0.15 mmplastic 0.005 Given the room volumes (m3/s) we can calculate the required duct size , air flow rates (m/s) and FDash (Alsthul Approx) 0.0265brickwork/concrete 1.3 pressure drops (pa) Friction Factor 0.0265

rough brickwork 5 Pressure Drop / m 0.86 pa/m

Minimum and maximum criteria have been based on CIBSE guide B

Properties of Air (STP) Fitting K Factor 0.160673

Temperature (°C) 20 Duct sizing and general design criteria have been based on CIBSE guides B and CBarometric Pressure (kPa) 101.325 Fitting Pressure Drop 8.60 pa

density (kg/m³) 1.20 Pressure loss criteria has been limited in final ducts to each room to 1.00 pa per metre, duct in branchesdynamic viscosity (Pa/m) 0.000018 may slightly be in excess of this requirement to optimise the size of the duct and due to physical

kinematic viscosity (m²/s) 0.0000150 constraints of the actula size of the plant room may have dictated smaller duct with increase in rsistance but the limiting factors of using the duct velocities as detailed in CIBSE guides have .had an overiding influence on this duct sizing calculation Note

K Factor = P so E18

______________ X 10 divided by4. Method

0.6 * v squared 0.6 X E12 X E12There are 5 different types of calculation to complete.

1. Each room has an assigned a volume flow ( M³/s ) calculated from the room volume then multiplied by Dynamic pressure X factor of 10

A) Firstly to Calculate the duct size based on the Volume Flow rate (M³/s) Where P is the pressure drop

B) The Duct Size gives the required Duct area and V is the Velocity per metre, squared

CALCULATION TITLE:

VENTILATION SYSTEM DUCT SIZING,

M²

For rectangular duct, width "a" X width "b" = cross sectional area Multiply by the Dynamic pressure and again by 10 is by a Factor of experienceThis may be reduced or increased depending on TM 23 air leakage requirements,…..but as a general guide 10 is used

For circular duct = (pye r squared)Then air velocities ,..may be increassed by a factor of 10% to allow for any subsequent air leakage

C) From the area of the duct the simpliest formula we can use to calculate the flow ratewe can calculate the flow rate in M/sec by the following formula

Flow Rate = Flow Rate ( M³/s )M/sec area of duct ( M² )

Once that we have the flow rate (M/sec), we can determin whether the duct size is as required, whilst keeping the velocities within minimum and maximumcriteria as detailed within the CIBSE Guides

D) Once that we have settled on the duct size and duct velocity we can determine the Pressure loss through each of the duct fittings bythe following formula and criteria

K Factor = PD for fittings AS CIBSE / HVAC CALC GUIDELINES

K Factor = K X Pv where K is = to 0.5 X P X V squared

where P is eqaul to 1.2 Kg/m density of air

Pv = 0.5 X P X V squared.,. Where V = velocity in m/s

USE OF THIS K FACTOR ALLOWS NO AIR LEAKAGE, but this may be considered

There are several alternatives to working out the Pressure loss and pressure loss factorsof fittings but the CIBSE Guides give detailed explanation to this criteria and formula's

E) Once that we have settled on the duct size and duct velocity we can also determ

USE OF D'ARCY Formula

Pressure loss through the duct itself bythe following formula and criteria

use of D'Arcy Formula

h = X Pa

2 g a b Pw

Where

h is the Head Loss due to friction in WG mm

a is the width of the duct (M)

b is the other width/side of duct (M)

L is the length, of 1 metre of duct

V is the Velocity of Duct Flow (Squared)

пr²

2 ( a + b ) f L V²

ENTER DATAbelow

Pa is the Density of Air 1.2 Kg/m³Pw is the Density of Water 998 Kg/m³f being the frictional coeffitiant 0.45

= DATA to ,..INPUT Note that 1 mm WG = 9.81 pa resistance

mm mmExample Volume flo 3.99 m / sec Duct size 0.300 0.200

Sum of 2 ( a + b ) f 0.45 value 1 0.500

15.9201 value 2

Sum of Value 1 * 2 7.164045

Sum of 2 g a b 1.1772

Sum of Pa 0.001202Pw

Sum of of D'Arcy Formula 6.085665 ### M WG

h = 7.317433 mm WG

or ### pa / metre OUTPUT / ANSWER

We have a program in excell which calculates the duct size, given the volume flow rateand calculates the pressure loss per metre run and pressure loss per fitting(Screen shots of this ductalator, program have been included at the end of this documentfor information and examples)

The calculations in this document will determine the required Velocity through the duct the specified size of duct and the required pressure drop through each section of duct and fitting associated with the duct installation, however there may be slight variations betweenthe computor calculation and the manual calculation method.

sum of V²

OUTPUT / ANSWER

EXAMPLE Type 2

AS CIBSE ,..K Factors for fittings

DUCT Sizing

Volume Flow Rate 0.064 m³/sDuct Width 150 mmDuct Height 150 mm

Hydraulic Diameter 165 mm

Velocity 2.99 m/sDynamic Pressure 5.35 paReynolds Number 2.7E+04Roughness 0.15 mmFDash (Alsthul Approx) 0.0265Friction Factor 0.0265Pressure Drop / m 0.86 pa/m

Pressure loss Factor 0.75

Fitting K Factor s/t 4.01

Fitting Pressure Drop 5.35 pa

AS CIBSE / HVAC CALC GUIDELINESBSRIA Guide 30/2007 page 107or alternative K Factor = PD for fittings

K Factor =is the Pressure loss factor

K X Pv

0.6 X E12 X E12 where P is eqaul to 1.2 Kg/m density of air

Where V = velocity in m/s

USE OF THIS K FACTOR ALLOWS NO AIR LEAKAGE,

but this may be considered

where delta P is = to K x 0.5 X P X V ²

Pv = 0.5 X P X V ² (squared)

Multiply by the Dynamic pressure and again by 10 is by a Factor of experienceThis may be reduced or increased depending on TM 23 air leakage requirements,…..but as a general guide 10 is used

Then air velocities ,..may be increassed by a factor of 10% to allow for any subsequent air leakage

EXAMPLE Type 3

DUCT Sizing

Volume Flow Rate 0.064 m³/sDuct Width 150 mmDuct Height 150 mm

Hydraulic Diameter 165 mm

Velocity 2.99 m/sDynamic Pressure 5.35 paReynolds Number 2.7E+04Roughness 0.15 mmFDash (Alsthul Approx) 0.0265Friction Factor 0.0265Pressure Drop / m 0.86 pa/m

Fitting K Factor s/t 8.9181970.45 mm WG

Fitting Pressure Drop 4.46 pa

Simple Calculation of K FactorFOR FITTINGS

K = V squareddivided by 2g

where 2 g is

2 times Gravity at 9.81 mm WG

Times 9.81 to convert to pa