Skip to main content

.TT pocketEngineer softDesign

... pocketEngineer software for mobile design

pocketEngineer software  animated gif (free)  email me  buy now  thoughts   
...Ductulator Plus+
...aDuctulator (And)
...aBattMV (And)
...aKitchenExhaust (And)
...tRod Sizer (free)
...pocketPipe Sizer
...aPipeSizer (And)
...multi Pipes PD (And)
...aPocketGas (And)
...rhoAIR (free)
...aRhoAIR (free) (And)
...aPsychroAC (And)
...AirTAB superEZ
...Qcool Check
...aCriticalVel (And)
...aPocketPool (And)
ePF Loop Pdrop
...hydrant pressure drop
...Pumping Mainline
Rethink, Reinvent apps
...CurveFit Tracer
...gas suppression
...CA ring main Pdrop
.TT pocketEngineer  software - creating mobile design environment for engineers & designers ...
 rhoAIR v7.14 (free)

air density + psychrometric air properties calculator



To take a glance at all pocketEngineer software and OS requirements, click Overview.

 For Android, see aRhoAIR free.


ALERT! The original copy of rhoAIR is only available on this site. If you have downloaded it from other sites, you may have downloaded a fake/spam one. The original copy does not require setup installation, and there is no ads.

 rhoAIR: air density + air properties calculator 

rhoAIR is a state point psychrometric air properties calculator to find air density, vapour pressure, dew point temperature, moisture content, enthalpy, etc. It is specially designed by a professional engineer to replace the psychrometric chart. rhoAIR will change the way you normally find air properties and air density by using conventional psychrometric chart.

Aim: creating a mobile design environment (
ShowMe!) for the practising engineers & designers in today's mobile world.

Results: Instant solutions at your fingertips.



- calculate Air Density, DewPoint Temperature, various Vapour Pressure, Moisture Content, Specific Volume, Enthalpy, etc.
- input options for RH or Wetbulb Temperature.

- calculation formulation to ASHRAE guidelines.
- alternative method to using conventional Psychrometric Chart.
- mobile & independent program for Windows Mobile & Windows PC.

- in SI & IP units.

- save results function for printing.


 Did you know? . . .about Enthalpy Units 


It is incorrect to directly convert Enthalpy from SI unit (kJ/kg) to IP unit (Btu/lb), and vice versa. Hard to believe! Test it yourself.



 Did you know? . . .the definition of Standard air density = 1.204 kg/m3 ?  


The value is of course valid only for what is termed standard air conditions.


In the International Standard Atmosphere (ISA), standard temperature and pressure is 15 oC and 101325 Pa respectively. This gives the air density of 1.225 kg/m3 at sea level and the air does not contain water vapour, i.e. dry air.


At 20 oC, the dry air has a density of 1.204 kg/m3. At 20 oC and 101325 Pa, it may be referred to as Normal temperature and pressure conditions.


In AMCA 210 Standard for fan performance testing, standard air is defined as air with a density of 1.2 kg/m3 (at 20 oC, 50% RH and 101325 Pa approximately). see calculation example below.


ASHRAE 37 Standard for unitary air-conditioning testing defines standard air as dry air having a mass density of 1.204 kg/m (at 20 oC and 101325 Pa).


SMACNA 126 Standard for HVAC duct testing defines density of standard air equals 1.204 kg/m3.


Note that there are many definitions of standard temperature and pressure. To avoid confusion, it is  often necessary to state the standard reference conditions.



 Calculation Exapmle 

At 20 oC , 50% RH and sea level, find air density, dewpoint temperature, moisture content, enthalphy, etc?


Altitude, Z = 0 m
DryBulb, Tdb = 20 °C
Relative humidity, RH = 50 %
WetBulb, Twb = 13.8 °C
Air density, rho = 1.199  kg/m³
DewPoint, Tdp = 9.3 °C


Details . . .
(1) Atmospheric pressure, P = 101,325 Pa
(2) Saturation vapour pressure, Pws = 2,338.8 Pa
(3) Partial water vapour pressure, Pw = 1,169.4 Pa
(5) Humidity ratio (Moisture content), W = 7.262 g(water)/kg(dry air)
(6) Specific volume, v = 0.8402 m³/kg(dry air)
(7) Enthalpy, h = 38.55 kJ/kg




 Calculation Exercise 

A sling psychrometer reads 44 oC dry bulb temperature and 30 oC wet bulb temperature. Calculate air density and other psychrometric properties.



 Air Mixing Problems? 

rhoAIR is not designed to calculate mixing air psychrometric properties. See comparison below.







 State point psychrometric air properties yesyes 
 Air mixing psychrometric air properties noyes 
 AHU coil condensate flowrate noyes








 Price :  free download


OS requirements: Windows Mobile, Windows.



(1) For ultimate duct sizer, see  Ductulator+


(2) For Coil condensate and Air mixing calculations, see  Qcondensate.



For product sales, see buy now. For product enquiry, email me.