Bulletin #: 2009-002
Subject: New water table gives incorrect density at higher temperatures
Program affected: PIPE-FLO Professional, Flow of Fluids, PUMP-FLO
Approved by: RL
An error in the Water Table was discovered which affects the liquid density of water at higher temperatures. Above 302 ºF (150 ºC) there is significant deviation between the density calculated from the table and actual water density data from the International Association for the Properties of Water and Steam (IAPWS). This table was created to improve the accuracy of water density calculations at lower temperature ranges, particularly 32 to 212 ºF (0 to 100 ºC). It was first offered for download in the Knowledge Base beginning in February of 2008, the file name of this table was Water_IAPWS.ftbl. This table was then included as the default Water table (Water.ftbl) with the 2009 versions of PIPE-FLO Professional and Flow of Fluids, as well as PUMP-FLO version 10. An updated Water table has been created that fixes the inaccurate density data for higher temperatures, and has now been made available.
To determine whether you have the latest Water table, you can check the version number of the Water table installed on your computer. The latest Water table is version 2. To check the version number in PIPE-FLO or Flow of Fluids, go to the "Fluid Zones" dialog box and select "Water" from the installed fluid table list. The version number will be displayed near the bottom of the dialog box. In PUMP-FLO go to the "Fluid & NPSH" tab in the "System Data" dialog box and select "Water" in the installed fluid table list. The version number will be displayed directly below the installed fluid table list.
If you use the Water table at temperatures below 302 ºF (150 ºC), the liquid density is accurate and you will see very little change between the version 1 and version 2 of the Water tables. However, even if the error does not affect your system we recommend downloading the new Water table. The version 2 Water table download and installation instructions can be found in Knowledge Base article 1489, "New Water Table." The version 2 Water table will also be included with the maintenance release of the 2009 version of PIPE-FLO Professional and Flow of Fluids.
The inaccurate water table was available from February 2008 until October 2008 as a download. If you downloaded the Water_IAPWS.ftbl within this time period your table is incorrect and any PIPE-FLO Professional or Flow of Fluids project files that utilize that table will need to be updated once the version 2 Water table is installed. If you download the PIPE-FLO Professional 2009 or Flow of Fluids 2009 maintenance release, you will also need to update any files that use the Water table. For instructions on updating project files to use the version 2 Water table, refer to Knowledge Base article "New Water Table."