Sheet1Air PropertiesCommon properties for air can be taken from the table below:TemperatureDensitySpecific heat capacityThermal conductivityKinematic viscosityExpansion coefficientPrandtl's number- t -- -- cp -- l - x 10-6b x 10-3Pr(oC)(kg/m3)(kJ/kg.K)(W/m.K)(m2/s)(1/K)-1502.7931.0260.01163.088.210.76-1001.9801.0090.01605.955.820.74-501.5341.0050.02049.554.510.72501.2931.0050.024313.303.670.715201.2051.0050.025715.113.430.713401.1271.0050.027116.973.200.711601.0671.0090.028518.903.000.709801.0001.0090.029920.942.830.7081000.9461.0090.031423.062.680.7031200.8981.0130.032825.232.550.701400.8541.0130.034327.552.430.6951600.8151.0170.035829.852.320.691800.7791.0220.037232.292.210.692000.7461.0260.038634.632.110.6852500.6751.0340.042141.171.910.683000.6161.0470.045447.851.750.683500.5661.0550.048555.051.610.684000.5241.0680.051562.531.490.68Absolute and Kinematic ViscosityTemperatureDynamic ViscosityKinematic Viscosity- t -- -- -(oC)(N.s/m2) x 10-5(m2/s) x 10-5-401.571.04-201.631.1701.711.3251.731.36101.761.41151.801.47201.821.51251.851.56301.861.60401.871.66501.951.76601.971.86702.031.97802.072.07902.142.201002.172.292002.533.393002.984.844003.326.345003.647.971,0005.0418.2Altitude and Air PressureAltitudeBarometer(m)(mmHg)0749757431507352507263007234507096006957506819006681,0006581,2006431,3506321,5006201,8005982,1005772,400555Altitude and Air DensityAir density and specific volume as functions of altitude above sea level are indicated in the diagrams below:STP - Standard Temperature and PressureSTP - Standard Temperature and Pressure is 0oC and 101.325 kN/m2.NTP - Normal Temperature and PressureNTP - Normal Temperature and Pressure, commonly used for testing and documentation of fan capacities, is 20oC and 101.6 kN/m2 (60oF , 30 in Hg)Altitude and Specific Volume CorrectionThe specific volume of standard air at a certain altitude can be calculated by multiplying with the volume correction factor belowAltitudeVolume Correction Factor(m)(ft)00148016001.0599033001.11150050001.17198066001.24246082001.31297099001.39Air - Density and Specific WeightTemperatureDensitySpecific Weight- t -- -- -(oC)(kg/m3)(N/m3)-401.51414.85-201.39513.6801.29312.6751.26912.45101.24712.23151.22512.01201.20411.81251.18411.61301.16511.43401.12711.05501.10910.88601.06010.40701.02910.09800.99969.803900.97219.5331000.94619.2782000.74617.3173000.61596.0404000.52435.1425000.45654.47710000.27722.719Temperature and VolumeAir TemperatureVolume Correction Factor(oC)(oF)-46-500.77-40-400.79-34-300.81-28-200.83-23-100.85-1800.87-9100.89-5200.91-1300.934400.9410500.9618600.9822701.0027801.0232901.04381001.06431101.08491201.10Air volume used by single-acting pistonsThe diagram below indicates the air volume used by single-acting pistons.1 cubic feet = 0.028 m31 in = 25.4 mmSpecific Heat Ratio of AirSpecific Heat Ratio of Air at Standard Atmospheric Pressure in Imperial (BG) Units:TemperatureSpecific Heat Ratio- t -- k(oF)-401.401-201.40101.401101.401201.401301.401401.401501.401601.401701.401801.400901.4001001.4001201.4001401.3991601.3991801.3992001.3983001.3944001.3895001.3837501.36710001.35115001.329Specific Heat Ratio of Air at Standard Atmospheric Pressure in SI Units:TemperatureSpecific Heat Ratio- t -- k -(oC)-401.401-201.40101.40151.401101.401151.401201.401251.401301.400401.400501.400601.399701.399801.399901.3981001.3972001.3903001.3794001.3685001.35710001.321Speed of Sound in AirSpeed of Sound in Air at Standard Atmospheric Pressure in Imperial (BG) UnitsTemperatureSpeed of Sound- t -- c -(oF)(ft/s)-401004-2010280105110106220107430108540109650110660111770112880113890114910011591201180140120016012201801239200125830013484001431500150975016851000183915002114Speed of Sound in Air at Standard Atmospheric Pressure in SI UnitsTemperatureSpeed of Sound- t -- c -(oC)(m/s)-40306.20331.45334.410337.415340.420343.325346.330349.140354.750360.360365.770371.280376.690381.7100386.9200434.5300476.3400514.1500548.8Steam and Vapor EnthalpyWhen a liquid evaporates its go through a process wherethe liquid heats up to the evaporation temperaturethe liquid evaporate at the evaporation temperature by changing state from fluid to gasthe vapor heats above the evaporation temperature - superheatingThe heat transferred to a substance when temperature changes is often referred to as sensible heat. The heat required for changing state as evaporation is referred to as latent heat of evaporation.The most common vapor is evaporated water - steam or moist.EnthalpyEnthalpy of a system is defined as the mass of the system - m - multiplied by the specific enthalpy - h - of the system and can be expressed as:H = m h (kJ)whereH = enthalpy (kJ)m = mass (kg)h = specific enthalpy (kJ/kg)Specific EnthalpySpecific enthalpy is a property of the fluid and can be expressed as:h = u + p v (kJ/kg)whereu = internal energy (kJ/kg)p = absolute pressure (N/m2)v = specific volume (m3/kg)Part of the water vapor - steam - properties can be expressed in a table as:ptsvfvgufughfhgsfsg(bar)(oC)(m3/kg)(m3/kg)(kJ/kg)(kJ/kg)(kJ/kg)(kJ/kg)(kJ/kg.K)(kJ/kg.K)0.006112 1)0.010.0010002206.102,3750.00062,50109.1550,01070.0010001129.2292,385292,5140.1068.974..........1.01325 2)1000.0010441.6734192,5074192,6761.3077.355..........220373.70.002690.003681,9492,0972,0082,1784.2894.552221.2 3)374.150.003170.003172,0142,0142,0842,0844.434.43s is the steam entropysuffix - f - referrer to saturated liquidsuffix - g - referrer to saturated vapor - steamInternal energy - u - can be calculated from (2) and is often omitted in tables. vf - change very little and is also often omitted.1) referrer to absolute vacuum.2) referrer to water boiling at standard atmosphere.3) referrer to water critical point. For pressures above the critical point there is no definite transition from liquid to vapor.Specific Enthalpy of Saturated WaterSpecific enthalpy of saturated water - hf - can be obtained from tables as above. The value depends on the pressure.For saturated water at standard atmosphere - 2) -the specific enthalpy - hf - is 419 kJ/kg. At standard atmosphere - 1 bar (14.7 psi) - water starts boiling at 100 oC (212 oF).The specific enthalpy of water (in SI units) can be calculated from:hf = cw (tf - t0)wherehf = enthalpy of water (kJ/kg)cw = specific heat of water = 4.19 (kJ/kg.oC)tf = saturation temperature (oC)t0 = refer temperature = 0 (oC)Specific Enthalpy of Saturated SteamSpecific enthalpy of saturated steam - hg - can be obtained from tables as above. The value depends on the pressure.For saturated steam at standard atmosphere - 2) - the specific enthalpy - hg - is 2,676 kJ/kg.The specific enthalpy of evaporation can be calculated from:he = hg - hf (4)wherehe = specific evaporation enthalpy (kJ/kg)Specific evaporation enthalpy for water at standard atmosphere is:he = 2,676 - 419 (kJ/kg) = 2,257 (kJ/kg)Specific Enthalpy of Superheated SteamThe specific enthalpy of superheated steam can be calculated from:hs = hg + cps (ts - tf)wherehs = enthalpy of superheated steam (kJ/kg)cps = specific heat of steam at constant pressure = 1.860 (kJ/kg.oC)tf = saturation temperature (oC)ts = superheated steam temperature (oC)cps = 1.860 (kJ/kg.oC) at standard atmosphere. Be aware that cps varies with temperature.Common Units for Specific Enthalpy1 kJ/kg = 1,000 J/kg1 erg/g = 1E-4 J/kg1 Btu/lbm = 2,326 J/kg1 cal/g = 4,184 J/kgVacuumVacuum is defined as air pressure below atmospheric pressureThe vacuum level is the difference in pressure between the atmospheric pressure and the pressure in the evacuated system:0% vacuum = 760 torr = 14.7 psia = 29.92 inc mercury abs = 101.4 kPa abs50% vacuum = 380 torr = 7.3 psia = 15 inc mercury abs = 50.8 kPa abs99.9% vacuum = 1 torr = 0.01934 psia = 0.03937 inc mercury abs = 1.3 kPa absFor perfect vacuum (100%) - the pressure is 0 torr, 0 psia or 0 Pa abs.Vacuum in %, torr, mm Mercury, psi and kPaThe table below can be used to convert between common vacuum units:%TorrMicronpsia,InchesIncheskPaVacuum(mm Mercury)(lb/in2)MercuryMercuryabsabsAbsoluteGauge0760760,00014.729.920101.41.3750750,00015.529.50.4299.91.9735.6735,60014.228.91.0297.77.9700700,00013.527.62.3293.521600600,00011.623.66.3279.934500500,0009.719.710.2266.747400400,0007.715.714.2253.250380380,0007.31514.9250.861300300,0005.811.818.124074200200,0003.97.8522.0726.687100100,0001.933.9425.9813.3889090,0001.743.5426.381289.58080,0001.553.1526.7710.790.87070,0001.352.7627.169.392.16060,0001.162.3627.5689351.751,70012.0327.896.993.55050,0000.971.9727.956.794.84040,0000.771.5728.355.396.13030,0000.581.1828.74496.625.425,4000.14912128.923.497.42020,0000.390.78529.142.798.71010,0000.1930.39429.531.3997.67,6000.1470.29929.62199.911,0000.019340.0393729.880.1399.90.757500.01450.029529.890.199.990.11000.001930.0039429.9160.01399.9990.01100.0001930.00039429.91960.0013100000029.9201 psi (lb/in2) = 6,894.8 Pa (N/m2) = 6.895x10-3 N/mm2 = 6.895x10-2 barVelocities in Vacuum pipesThe air velocity in vacuum pipes can be estimated with the diagrams below.Standard and Actual Air Volume - cfmThe diagram is calculated for steel pipes schedule 40.Standard and Actual Air Volume - l/s

TemperatureDensityKinematic viscosityTemperatureDynamic ViscosityKinematic ViscosityTemperatureDensitySpecific WeightTemperature- t -Temperature- t -s is the steam entropycps = specific heat of steam at constant pressure = 1.860 (kJ/kg.oC)

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