ASHRAE SI (METRIC) GUIDE FOR HEATING ...ASHRAE documents published after January 1, 1976 shall be prepared using only SI (Metric) units, or shall be prepared using dual units, i.e.,SI

Service Application Manual SAM Chapter 620-82

Section 13B

ASHRAE SI (METRIC) GUIDE FOR HEATING, REFRIGERATING, VENTILATING AND

AIR CONDITIONING INTRODUCTION

It is the decision of the Educational and Examining Board of the Refrigeration Service Engineers Society to make its membership aware of the SI conversions. A lot of time and effort have been put in to prepare this ASHRAE Guide and RSES is thankful to ASHRAE for granting permission to reprint this guide.

Measurement practices all over the world are in various stages of transition to the modern metric system, Systeme International d' Unites. This system, known as SI, was developed by an international treaty organization for measurement, which has been in existence since 1875. First released in 1960, the new system represents the culmination of efforts begun in about 1900 to improve the metric system.

It is important to understand that SI is the modernized version of the metric system. Some of the previous metric units and practices are not necessarily compatible with SI. Only authorized SI units or authorized exceptions may used.

In addition to US Customary Units, there are Imperial (British) units, cgs units, and other metric units, which will be phased out in favor of the new international system. As can be understood, the retention of individual preferences for some units in various countries and in various disciplines has been and may remain an impediment to the realization of the full benefits of SI.

In June 1975, ASHRAE adopted SI and a timetable. In February 1977, the Board of Directors modified the timetable to read as follows:

ASHRAE documents published after January 1, 1976 shall be prepared using only SI (Metric) units, or shall be prepared using dual units, i.e.,SI (metric) units and conventional units, with the sequence of units left to the discretion of the author or editor. Exceptions in HANDBOOK volumes, Standards, and special publications may be authorized by the responsible ASHRAE staff in coordination with the ASHRAE Metric Committee.

After July 1, 1977, the use of SI units first, followed by conventional units, is encouraged in the preparation of ASHRAE publications, unless the material is already prepared in SI units only.

Exclusive use of SI (metric) units shall be required in ASHRAE publications when it is determined by the Board of Directors to be in the best interest of the membership. During the transition period, the Metric Committee will continue to disseminate educational materials to prepare the membership for the eventual exclusive use of SI units.

For the sake of brevity, this guide covers primarily information directly applying to the heating, ventilating, air conditioning and refrigerating industry.

The reference standard covering SI in ASHRAE publications is ASTM E 380-76, Standard for Metric Practice (American Society for Testing and Materials, 1916 Race Street, Philadelphia, PA 19103). For further information on subjects not covered in detail here, and for conversion values with more significant digits, refer to ASTM E 380.

I. UNITS AND SYMBOLS

The International System (SI) consists of seven base and two supplementary units, which can stand alone, and a number of derived units, which are combinations of base units or base and supplementary units. Some derived units have special names and symbols.

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Section 13B


AIR CONDITIONING BASE UNITS

Quantity Name Symbollength metre m mass kilogram kg time second s electric current ampere A thermodynamic temperature kelvin K amount of substance mole mol luminous intensity candela cd

SUPPLEMENTARY UNITS

Quantity Name Symbol plane angle radian rad solid angle steradian sr

II. USE OF BASE AND DERIVED UNITS

In SI there is one and only one unit for each physical quantity. There are the base and supplemental units, which may be modified by prefixes as indicated in Section III. All the derived units are defined by simple equations using the base units. This is known as a coherent system and is the simplest measurement system to use. It is incumbent upon the user to protect the basic simplicity of the system by adhering strictly to the approved units or authorized exceptions.

Angle

The correct unit for the plane angle is the radian. The degree and its decimal fractions may be used, but use of the minute and second is discouraged.

Area

The SI unit of area is the square metre (m2). Large areas are expressed in hectares (ha) or square kilometers (km2). The hectare is restricted to land or sea areas and is equal to 10,000 m2.

Energy

The correct unit of energy is the joule (J). However, the kilowatt hour (3.6 megajoules) is widely used as a measurement of electric energy. As kilowatt hour will eventually be replaced by the megajoule or gigajoule, kwh should not be used for any new applications. DERIVED UNITS

Quantity Name Formula Symbolacceleration - angular radian per second squared rad/s2 acceleration - linear metre per second squared m/s2 area square metre m2

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Section 13B


AIR CONDITIONING

3

conductivity, thermal, k watt millimetre per square metre degree Celsius W•mm/m2•°C or, watt per metre kelvin W/m•K

density - energy joule per cubic metre J/m3 density - heat flux watt per square metre W/m2 density - mass kilogram per cubic metre kg/m3 energy, enthalpy - work joule N • m J energy, enthalpy - specific joule per kilogram J/kg entropy - heat capacity joule per kelvin J/K entropy - specific joule per kilogram kelvin J/kg•K force newton kg•m/s2 N frequency - periodic hertz 1/s Hz frequency- rotating revolutions per second (pref.) r/s inductance henry Wb/A H moment of a force newton metre N•m potential, electric volt W/A V power, radiant flux watt J/s W pressure, stress pascal N/m2 Pa resistance, electric ohm V/A Ω velocity - angular radian per second rad/s velocity-linear metre per second m/s viscosity - dynamic pascal second Pa•s viscosity-kinematic square metre per second m2/s volume cubic metre m3 volume, specific cubic metre per kilogram m3/kg

Force

The correct unit of force is the newton (N). Do not use the word weight and do not use kilogram force. The newton is also used in combination units that include force.

pressure or stress N/m2 = Pa (pascal)

work N•m = J (joule)

power N•m/s = W (watt)

Mass

The correct unit of mass is the kilogram (kg). Among the base and derived units of SI, the unit of mass is the only one whose name, for historical reason, contains a prefix. Names of decimal multiples and submultiples of the unit mass are formed by attaching prefixes to the word gram. Do not use the word weight, as this could be confused with force. The multiple—megagram, (Mg) or tonne (t) is the appropriate unit for measuring large masses.


Section 13B


AIR CONDITIONING Pressure

The correct unit of stress or pressure which is force per unit area is the newton per square metre. This unit has been given the special name, pascal (Pa). No other units are acceptable. There is no equivalent symbol for psig or psia, so if there is a possibility of misunderstanding, spell out Pa absolute or Pa gage.

Temperature

The correct unit of temperature is the kelvin, which is equal to a degree Celsius (formerly called degree centigrade). The thermodynamic temperature (absolute temperature) is related to Celsius as follows:

t = T-T0 where t = degrees Celsius

T = thermodynamic temperature

T0 = 273.15°K by definition

Time

When expressing rates, the correct unit of time is the second. Do not use the minute or hour. In some cases of long cycles it may be necessary to use the day, week, month, or year.

Exception: revolution per minute may be used, but revolution per second is the correct and preferred unit.

Volume

The correct unit for volume is the cubic metre. The cubic decimetre, which has the special name litre (l), is a regularly formed submultiple of the cubic metre. This is the correct and convenient unit to replace gallon and cubic foot. Litre per second would therefore replace gpm and cfm. A smaller correct unit is the millilitre per second. Note that the litre is restricted for use only with liquids and gases and for the volume of a vessel.

III. PREFIXES

Prefixes indicate orders of magnitude in steps of 1 000. This provides a convenient way to express large and small numbers and to eliminate non significant digits and leading zeros in decimal fractions. The following are the most used prefixes.

Prefix Symbol Represents giga jig'a (i as in jig; a as in about) G 1 000 000 000 109 mega (as in megaphone) M 1000 000 106 Kilo (kill-oh) k 1 000 103 milli (as in military) m 0.001 10–3

micro (as in microphone) µ 0.000 001 10–6

nano (nan-oh) (an as in ant) n 0.000 000 001 10–9

126 000 watts becomes 126 kilowatts

0.045 metre becomes 45 millimeters

65 000 metres becomes 65 kilometers

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AIR CONDITIONING

5

The following prefixes should be avoided, except that centimeter is used for anatomical measurements, cloth, and clothing sizes.

Prefix Symbol Representshecto (heck-toe) h 100 102 deka deck'a (a as in about) da 10 10¹ deci (as in decimal) d 0.01 10–1 centi (as in centipede) c 0.01 10–2

To realize the full benefit of the prefixes when expressing a quantity by numerical value, choose a prefix so that the number lies between 1 and 1 000.

Except that in tables of values of the same quantity or in a comparison of values in a given situation it is preferable to use the same multiple throughout. Also for certain measurements in particular applications specific units are customarily used.

The litre per second is used for water and air flow even though the number may exceed 1000.

The millimetre is used for dimensioning architectural (construction) and mechanical engineering drawings, even when the numbers far exceed 1000 mm.

Compound units

A compound unit is a derived unit not having a special name and expressed with two or more units. The prefix is attached to a unit in the numerator.

V/m not mV/mm

mN•m not N•mm (torque)

MJ/kg not kJ/g

Compound prefixes formed by the juxtaposition of two or more prefixes are not used.

2 nm not 2 mµm

6 m3 not 6 kl


Section 13B


AIR CONDITIONING Exponential Powers

An exponent attached to a symbol containing a prefix indicates that the multiple or sub multiple of the unit (the unit with its prefix) is raised to the power of 10 expressed by the exponent.

1 mm3 = (10–3m)3 = 10–9m3

1 ns–1 = (10–9s)–1 = 109s–1

1 mm2/s = (10–3m)2/s = 10–6m2/s

IV. NUMBERS

Large Numbers

The recommended international practice for large numbers is to separate the digits into groups of three—counting from the decimal to the left and to the right-and to use a space to separate the groups. In numbers of four digits, the space is not necessary except for uniformity in tables.

Examples:

2.345 678 73 846 635 041 600.00 0.113 501 7 258

Small Numbers

When writing numbers less than one, a zero should always be written before the decimal marker.

0.046

Decimal Marker

The recommended decimal marker is a point on the line (period). In some countries, a comma is used as the decimal marker.

V. SYMBOLS

Correct usage of symbols is very important—an incorrect symbol may change the entire meaning of a quantity. For this reason there are international agreements on uniform rules for using symbols. There is only one correct way to use symbols and this must be followed.

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AIR CONDITIONING

7

There are no abbreviations in SI—only symbols. Therefore symbols are not followed by a period, except at the end of a sentence.

SI not S.I.

s not sec

A not amp

Symbols are written in lower case unless the unit name has been taken from a proper name. In this case the first letter of the symbol is capitalized.

m, metre

W, watt

Pa, pascal

Symbols and prefixes are printed in upright (roman) type regardless of type style in surrounding text.

. . a distance of 56 km between...

Exception:

Symbols for use with computers with limited character sets are covered by ISO Standard 2955.

Unit symbols are the same whether singular or plural.

1kg 14kg

1mm 25mm

A space is left between the numerical value and the symbol.

35 mm not 35mm

100 W not 100W

Exception:

No space is left between the numerical value and the symbol for degree Celsius and degree of plane angle. Note that °C is the symbol for degree Celsius and C is the symbol for Coulomb.


Section 13B


AIR CONDITIONING 20°C not 20 °C or 20° C

45° not 45 °

Symbol for product—use a raised dot •

N•m

mPa•s

W/m2•°C

Symbol for quotient - use one of the following forms:

NOTE:

use only one solidus (/) per expression.

Symbols and names are not mixed in the same expression.

m/s or metres per second, not metres/second, and not metres/s

J/kg or joules per kilogram, not joules/kilogram, and not joules/kg

No letters may be attached to a unit symbol.

MWe—incorrect

Vac—incorrect

VI. NAMES

Spelled out names are treated as common nouns in English. Therefore, the first letter of a unit is not capitalized except at the beginning of a sentence or in capitalized material, such as a title.

watt, volt, pascal, newton, ampere, kelvin

Exception:

The first letter of Celsius is always capitalized.

Never begin a sentence with a unit symbol—either rearrange the words or write the unit name in full.

Plurals for spelled out words are used when required by the rules of English grammar.

metre metres

kelvin kelvins

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Section 13B


AIR CONDITIONING

9

henry henries

kilogram kilograms

Exceptions:

hertz hertz

lux lux

A space or hyphen is not used between the prefix and unit name.

kilometre not kilo metre or kilo-metre

milliwatt not milli watt or milli-watt

When a prefix ends with a vowel and the unit name begins with a vowel, both vowels are retained and both are pronounced.

kiloampere

Exceptions:

hectare

kilohm

megohm

Compound units formed by multiplication and division.


Section 13B


AIR CONDITIONING Product:

Leave a space between units.

newton metre

volt ampere

Quotient:

Use the word per, not a solidus (/).

metre per second not metre/second

Powers:

Use the modifier squared or cubed after the unit name.

metre per second squared

Exception:

area or volume measurements—place the modifier before the units.

square millimetre

cubic metre

VII. CONVERSIONS

A Soft Conversion is the conversion of customary dimensions or capacity specifications to equivalent metric units.

A Hard Conversion is the changing of actual physical dimensions or capacity specifications so that the measurements are in rounded metric units.

When making conversions, it must be borne in mind that a converted value has no more accuracy than the original measurement. Therefore, after making the conversion, round off the answer to no more than the same number of significant figures as the original measurement.

The conversion values in this guide have been rounded off to three or four significant figures, which is generally sufficient for practical applications.

CONVERSION FACTORS

Multiply By To Obtain acre 0.405 ha bar 100 kPa barrel (42 gal) 159 l Btu, IT 1.055 kJ Btu/ft3 37.3 kJ/m3, J/l Btu/gal (US) 0.279 kJ/l

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Section 13B


AIR CONDITIONING

Btu•in/ft2•hr•°F (k, thermal conductivity) 144 W•mm/m2•°C Btu/h 0.293 W Btu/ft2 11.4 kJ/m2 Btu/h•ft2 3.15 W/m2 Btu/ft2•hr•°F (U, overall heat trans coeff), (C, thermal conductance) 5.68 W/m2•°C Btu/lb 2.33 kJ/kg Btu/lb•°F (c, specific heat) 4.19 kJ/kg•°C bushel 0.0352 m3 calorie, gram 4.19 J calorie, kilogram; kilocalorie 4.19 kJ centipoise (µ, dynamic viscosity) 1.00 mPa•s centistokes (µ/p, kinematic viscosity) 1.00 mm2/s cents per gallon 0.264 ¢/l cents per gallon (no. 2 fuel oil) 0.0677 $/GJ cents per gallon (no. 6 fuel oil) 0.0632 $/GJ cents per gallon (propane) 0.112 $/GJ cents per kWh 2.78 $/GJ cents per therm 0.0948 $/GJ cost, $ per square (100 sq ft) 0.108 $/m2 cost, $ per square foot 10.8 $/m2 cost, $ per pound 2.205 $/kg cost, $ per ton (refrigeration) 0.284 $/kW EDR hot water (150 Btu/h) 44.0 W EDR steam (240 Btu/h) 70.3 W ft2•h•°F/Btu (R, thermal resistance) 0.176 m2•°C/W ft 0.3048 m ft 304.8 mm ft/min, fpm 0.00508 m/s ft/s, fps 0.3048 m/s ft of water 2.99 kPa ft2 0.0929 m2 ft2/s (µ/p, kinematic viscosity) 92 900 mm2/s ft3 28.3 l ft3 0.0283 m3 ft3/h, cfh 7.87 ml/s ft3/min, cfm 0.472 l/s ft3/s, cfs 28.3 l/s ft-lb (work) 1.36 J ft-lb/min (power) 0.0226 W

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Section 13B


AIR CONDITIONING

gallon (US) 3.79 l gallon (US) 0.00379 m3 gph (US) 1.05 ml/s gpm (US) 0.0631 l/s grain (1/7000 lb) 0.0648 g gr/gal 17.1 mg/l gr/lb 0.143 g/kg horsepower (boiler) 9.81 kW horsepower 0.746 kW inch 25.4 mm in of mercury 3.38 kPa in of water 249 Pa in/100 ft, thermal expansion 0.833 mm/m in2 645 mm2 in3(volume) 16.4 ml in3/min (SCIM) 0.273 ml/s in3 (section modulus) 16 400 mm3 in4 (section moment) 416 000 mm4 km/h 0.278 m/s kWh 3.60 MJ kilopond (kg force) 9.81 N kip 4.45 kN kip/in2(ksi) 6.90 MPa litre 0.001 m3 micron of mercury 133 mPa mile 1.61 km mile, nautical 1.85 km mph 1.61 km/h mph 0.447 m/s millibar 0.100 kPa mm of mercury (torr) 0.133 kPa mm ot water (20°C) 9.79 Pa metre of water 9.79 kPa ounce (mass, avoir) 28.3 g ounce (force or thrust) 0.278 N ounce (liquid) 29.6 ml ounce inch (torque, moment) 7.06 mN•m ounce (avoir) per gallon 7.49 g/l perm (permeance) 57.4 µg/kPa•s•m2 perm inch (permeability) 1460 µg•mm/kPa•s•m2 (perm

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Section 13B


AIR CONDITIONING

13

mm) pint (liquid) 473 ml pound lb (mass) 0.454 kg lb (force or thrust) 4.45 N lb (mass) 454 g lb/ft (uniform load) 1.49 kg/m lb/ft•h (µ, dynamic viscosity) 0.413 mPa•s lb/ft•s (µ, dynamic viscosity) 1 488 mPa•s lb/h 0.126 g/s lb/min 0.00756 kg/s lb of steam per hour @ 212°F (100°C) 0.284 kW lbf/ft2 47.9 Pa lbf•s/ft2 (µ, dynamic viscosity) 47 900 mPa•s lbm/ft2 4.88 kg/m2 lb/ft3(p, density) 16.0 kg/m3 lb/gallon 120 kg/m3 lb ft (torque or moment) 1.36 N•m lb in (torque or moment) 113 mN•m ppm 1.00 mg/kg psi 6.89 kPa quart (liquid) 0.946 l square (100 sq ft) 9.29 m2 tablespoon 15 ml teaspoon 5 ml therm 106 MJ ton, long (2 240 lb) 1.02 Mg (tonne) ton, short (2 000 lb) 0.907 Mg (tonne) ton, refrigeration 3.52 kW watt per square foot 10.8 W/m2 yd 0.914 m yd2 0.836 m2 yd3 0.765 m3


Section 13B


AIR CONDITIONING UNIT AND SIZE IN TYPICAL CALCULATIONS

The following information is provided for the purpose of permitting one to become familiar with the units and size of numbers involved in typical calculations.

Gravity, Standard

9.806 65 m/s2 exactly, per CGPM 1901

Atmospheric Pressure Of Air

101.325 kPa (ISO Standard - same as present standard)

Temperature Conversion

°C = (°F - 32)/1.8

°F = 1.8°C + 32

Gas Constants (Ideal Gases)

R = 8.314 kJ/kg•mol•K

where K = thermodynamic temperature, kelvin

air

water vapor

Properties Of Air At Standard Atmospheric Pressure 101.325 kPa

Temperature Density, p Viscosity, μ Conductivity, k°C kg/m3 Pa•s W•mm/m2•°C -10 1.342 16.77 0 1.293 17.24 24.2 10 1.247 17.71 25.1 20 1.205 18.18 26.0 30 1.165 18.65 26.7 40 1.128 19.12 27.5 50 1.093 19.59 28.2

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Section 13B


AIR CONDITIONING Specific Heat

dry air

constant pressure cp = 1.005 kJ/kg•°C

constant volume cv = 0.717 KJ/kg•°C

superheated water vapor = 1.89 kJ/kg•°C

moist air * = 1.024 kJ/kg•°C

*includes 10 grams of moisture per kilogram of dry air

Heat Capacity—Air

sensible heat hs = 1.23 Δt Q = watts

latent heat hl= 3.00 Δw Q = watts

total heat ht = 1.20 Δh Q - watts

where Δt = temperature difference, °C or kelvins

Δw = moisture content difference, grams per kilogram (g/kg) dry air

Δh = enthalpy difference, kilojoules per kilogram (kJ/kg) dry air

Q = volume flow rate, litres per second (standard air) (l/s)

Units For Moisture Content Of Air

grams per kilogram of dry air, g/kg

Mass Density, Dry Air

where

p = mass density, kg/m3

p = pressure, kilopascals, kPa

T = absolute temperature, kelvins

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Section 13B

RAE SI (METRIC) GUIDE FOR HEATING, REFRIGERATING, VENTILATING AND

AIR CONDITIONING

16

ASH

Velocity, Air

V = 1.30

where V = velocity, metres per second, (m/s)

p = velocity pressure, pascals, (Pa)

Velocity Pressure

Pv = pV2/2

where Pv = velocity pressure, pascals (Pa)

p = density kg/m3

V = velocity m/s

Duct Dimensions

size Length cross sectional area diameter supports

mm × mm m mm mm, ctr to ctr

Pressure Of Air Using Manometer

Measure height of water column in mm. multiply by 9.81 = pressure in pascals, Pa. (multiplying by 10 is close enough for practical purposes.)

Typical Range Of Air Velocities, M/S

use residences commercial industrialfilters 1.3-1.5 1.5-1.8 1.8-2.5 cooling coils 1.5-2.0 2.0-2.5 2.5-3.5 outside air intakes 2.5-4.0 2.5-4.5 2.5-6.0 heating coils 2.3-2.5 2.5-4.0 3.5-5.0 air washer 2.5 2.5 2.5 fan inlet 3.5-4.5 4.0-5.0 5.0-7.0 fan outlet 5.0-8.5 6.5-11.0 8.0-14.0 main duct 3.5-6.0 5.0-8.0 6.0-11.0 branch duct 3.0-5.0 3.0-6.5 4.5-9.0


Section 13B


AIR CONDITIONING Ventilation Rates–Typical

per square metre floor area

1.25 /s•m2 (0.25 cfm/ft2)

air change rate

changes per hour = 3.6 Q/V

where V = space volume, cubic metres (m3)

Q = volume flow rate, litres per second (l/s)

Fan Power

where P = outlet power, watts (W)

Q = volume flow rate, liters per second (l/s)

Δp = pressure difference across fan, pascals (Pa)

Fan Tip Speed

where St = tip speed (m/s)

d = fan diameter (mm)

N = revolutions per second (rps)

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Section 13B


AIR CONDITIONING Sound

Power level, decibel, dB

reference: 1 picowatt (pW - 10–12 watt)

Pressure level, micropascal (µPa)

reference: 20 µPa

Velocity - through air at 20°C and 50% RH

344 m/s

Conductance

C = watts per square metre degree Celsius, W/m2•°C

Heat Transmission

W = A × U ×Δt

where A = area, square metres (m2)

U = overall heat transfer coefficient (W/m2•°C)

Δt = degrees Celsius (kelvins)

W= watts

Fouling Factor, Heat Exchanger

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Section 13B


AIR CONDITIONING Vapor Transmission

where w = mass flow rate of vapor transmitted, µg/s

µ= permeability, perm mm

(perm mm = 57.5×perm inch)

A = area, m2

Δp = difference of vapor pressure between ends of flow path, kPa

L = length of flow path, mm

Fuel Energy

number 2 fuel oil, 140 000 Btu/gal = 39 MJ/l

number 6 fuel oil, 150 000 Btu/gal = 42 MJ/l

propane, 84 000 Btu/gal = 23.5 MJ/l

natural gas, 1 000 Btu/ft3 = 37.3 kJ/l

kilowatt hour = 3.6 MJ

therm, 100 000 Btu = 105.5 MJ

Fuel Burning Rates

power (watts) = volume rate of flow × fuel energy per unit volume

oil, propane

kW = kJ/s = (ml/s) • (MJ/l )

natural gas

kW = kJ/s = (l/s) • (kJ/l)

Volume Rate Of Flow

Litre per second l/s is the recommended flow unit for air conditioning usage, both air and water. With water, this is approximately one kilogram per second (kg/s). The range 1 to 1 000 l/s is approximately equal to 16 to 16 000 gpm.

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Section 13B


AIR CONDITIONING Circulating Water Requirement

where Q = rate of flow l/s

H = cooling or heating kilowatts, kW

Δt = temperature ditterence, kelvins or degrees Celsius

Velocity In Pipe

where V= velocity m/s

O = volume rate of flow, litres per second, l/s

d = internal pipe diameter, millimetres, mm

Reynolds Number

where p = density, kg/m3

d = internal pipe diameter mm

V = velocity, m/s

µ= dynamic viscosity, mPa•s

Friction Factor, f [MOODY]

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Section 13B

ASHRAE SI (METRIC) GUIDE FOR HE RIGERATING, VENTILATING AND G

21

ATING, REF

AIR CONDITIONIN

Pressure Loss Due To Pipe Friction

where Δp = pressure loss, kPa

f = friction factor

p = mass density, kg/m3

L = length of pipe, m

d = inside diameter of pipe, mm

V = velocity, m/s

Typical Pressure Drop, Coil

water side 5 to 50 kPa

Absolute Roughness

Material Є, mm Smooth drawn tubing brass, copper, steel 0.000 46New steel pipe 0.046 Cast iron pipe, asphalt ctd 0.12 galvanized iron pipe 0.15 Cast iron pipe, asphalt ctd 0.26 Concrete, medium rough 0.91

PIPE/CONDUIT Nominal Sizes

US Inch ISO mm i.d. mm Є/d A m2 l/m 1/8 6 6.8 0.006 765 0.000 4 0.0401/4 8 9.2 0.005 000 0.000 7 0.0703/8 10 12.5 0.003 680 0.000 12 0.1201/2 15 15.8 0.002 893 0.000 20 0.2003/4 20 20.9 0.002 182 201 0.000 34 0.3401 25 26.6 0.001 721 729 0.000 56 0.5601-1/4 32 35.1 0.001 31 0.000 97 0.9701-1/2 40 40.9 0.001 125 0.001 31 1.3102 50 52.5 0.000 878 76 0.002 16 2.1602-1/4 65 62.7 0.000 729 734 0.003 9 3.0903 80 77.9 0.000 587 591 0.004 77 4.7703-1/2 90 90.1 0.000 507 511 0.006 38 6.3804 100 102.3 0.000 447 450 0.008 22 8.220


Section 13B


AIR CONDITIONING

5 125 128.2 0.000 350 9 0.012 91 12.916 150 154.1 0.000 299 0.018 65 18.658 200 202.7 0.000 227 0.032 27 32.2710 250 253.2 0.000 180 0.050 35 50.3512 300 304.8 0.000 151 0.072 97 72.97

Thermal Expansion—Pipe & Tubing

(in mm/m, temperature range measured from 0°C)

Temperature Range, °C Steel Pipe Copper Tubing Aluminum Tubing0 0 0 0 50 0.57 0.89 1.18

100 1.14 1.77 2.35 150 1.71 2.66 3.53 200 2.28 3.55 4.70 250 2.85 4.43 5.88 300 3.42 5.32 7.05

Water

Heat of vaporization at 101.325 kPa and 100°C 2257 kJ/kg

Heat of fusion at 0°C 335 kJ/kg

Average specific enthalpy, 40°C through 100°C 4.2 kJ/kg•°C

Triple point (ice, water and steam) 0.01°C 273.16°K

Properties Of Water At Saturation Temperatures

Temp Specific Enthalpy Density Viscosity°C kJ/kg kg/m 3 mPa•s 0.01 0.00 999.8 1.78

4 16.8 1000.0 1.56 5 21.1 999.9 1.52 6 25.3 999.9 1.48 7 29.5 999.9 1.44 8 33.6 999.8 1.39 9 37.9 999.8 3.35

10 42.0 999.7 1.30 20 83.9 998.2 1.002 30 125.7 995.7 0.797 40 167.5 992.3 0.652 50 209.3 998.1 0.546

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Section 13B


AIR CONDITIONING

60 251.1 983.1 0.466 70 293.0 977.7 0.404 80 334.9 971.7 0.354 90 377.0 965.3 0.314

100 419.1 958.3 0.281 120 503.7 943.1 0.230 140 589.0 926.1 0.195 160 675.6 907.4 0.169 180 763.1 886.9 0.149 200 852.4 864.7 0.134

Typical Mass Densities (At 20°C)

GASES (101.325 kPa) kg/m3 Butane 2.412 Propane 1.829 Oxygen 1.330 Air, dry 1.205 Carbon dioxide 1.970 Air, 50% RH 1.191 Acetylene 1.173 Nitrogen 1.164 Natural Gas 0.719 Helium 0.166 Hydrogen 0.083


LIQUIDS kg/m3 Mercury 13,550 Sulphuric acid 1830 R-12 1329 Glycerine 1264 Battery electrolyte 1260 R-22 1213 Water 998 Mineral oil 900 Kerosene 820 Ethyl alcohol 791 Gasoline 730 Propane 580

23


Section 13B


AIR CONDITIONING

24


SOLIDS kg/m3 Lead 11,300 Copper 8,900 Steel 7,830 Cast Iron 7,200 Aluminum 2,700 Glass 2,500 Concrete 2,300 Brick 1,921 Hardwood 750 Softwood 540 Fiberglass board 80 Styrofoam 20

Copyright © 1989, 2001, By Refrigeration Service Engineers Society

Documents

ASHRAE SI (METRIC) GUIDE FOR HEATING ...ASHRAE documents published after January 1, 1976 shall be prepared using only SI (Metric) units, or shall be prepared using dual units, i.e.,SI