Psychrometrics of Air

The computer program PSYCHRO is an ACADS-BSG program which was developed by G.J.Van Aken in Canberra ACT. It computes the thermodynamic properties of moist air, at any atmospheric pressure, from its dry bulb temperature and one of four other parameters. The program applies to air conditioning and refrigeration, or any process involving heat and mass transfer in moist air. The program has been tested against ASHRAE data over the temperature range of -40 C to 200 C at standard atmospheric pressure (101.325 kPa) and at 84.556 kPa. However, the sub-programs used in this program are valid for the temperature range of -125 C to the critical temperature of water at 374.15 C, and a pressure range from 1 to 5000 kPa.


All input data is interactively entered through the keyboard as prompted on the screen.

First the atmospheric pressure must be established. This may be entered directly in kPa or, alternatively, by elevation in metres above sea level in the range from -1000m to 12000m (113.930 kPa to 19.286 kPa). The default is for 101.325 kPa which is the standard atmospheric pressure at sea level. A listing of elevations for some typical locations can be displayed upon request. Pressures occurring outside the valid elevation range must be entered directly in kPa, in which case the valid range is from 1kPa to 5000kPa.

The next request is for the entry of the dry bulb temperature. The valid range for this parameter is from -125 C to the critical temperature of water at 374.15 C. After this entry one of four options must be selected and entered as the second parameter to complete the input requirements for the program. These options are:

Wet Bulb Temperature Relative Humidity

Dew Point Temperature Humidity Ratio


All the parameters that can be obtained from a psychrometric chart are displayed and in addition to this the density and specific heat of the moist air mixture, and the water vapour pressures are also displayed.

PSYCHRO is one of the ACADS BSG Shareware programs. Shareware relies upon the honesty of the software users to pay for the software they use. It avoids the cost of marketing and promotion by inviting users to give copies to their friends. A nominal registration fee is charged for the program, this fee contributing to the original development and future enhancements. By registering, users are kept informed of future updates and improvements to the program.

The program is available for use on a micro computer running MSDOS. Copies of the program are supplied on 3.5″ IBM formatted diskettes.

For further information including pricing, contact the ACADS-BSG Office in Glen Iris on Ph +613 9885 6586 or at

Stay informed

Keep up with ACADS – BSG’s latest news. Sign up below or follow us on LinkedIn.

Website Subscription Form

function checkMandatory7438000000146001() { for(i=0;i

The user interface for HYENA+ is much cleaner and more user friendly than the UI used for the original HYENA program. This makes the experience more enjoyable, easy, and less taxing when using the program for long periods of time. HYENA is an excellent tool to have and its now web-based nature with HYENA+ has allowed it to become even more beneficial.

– M. Cummings

It has always been a pleasure dealing with ACADS-BSG team due to their helpful nature and quick response time to any inquiries and technical issues. Camel\Hyena works out of the box and install time is in seconds, I cannot recommend any other company that provides better customer service other than Catherine and her team.

– Marvin D

Catherine and the team at ACADS provide customer service of the highest standards always offering the best solutions for our business with fast response times. I would highly recommend ACADS-BSG.

– Amy

The ACADS BSG suite of software has been used by VOS Group for 30 years. We as a company have grown as the software capabilities have changed with usability and technology. The support from head office has always been quick and accurate, with a resolve to overcome any obstacles. We have always found the outputs to be accurate and reliable and a good basis for good engineering design.

– Shayne C

Moving to a cloud based platform has improved the overall performance of the software. [being able to log in from any device] has improved my overall productivity as I only need to carry my smart phone or a tablet, and I can do my job remotely. Tools and functions are clearly organised within the new interface reducing any confusion for a new user. Copy+ Paste option saves a lot of time for Engineers like me. It just works like an Excel Sheet, where you can copy items and paste them somewhere else. It saves a lot of time especially if you are working on a single project and you want to do multiple calculations.

[HYENA+] allows me to quickly switch from one calculation to another without losing any data. This has reduced the overall lead time in doing calculations. I am sure [HYENA+] will have a positive impact on the Fire Industry.

– Ahkil M