I found that Lufft had a new sensor IRS31.
http://www.lufft.de/?lang=en&kat=Produkte:Produktsuche&PHPSESSID=0unb160qjocforu6451hq4r577&Suche=byNr&Nr=8510.U050
price can be seen here
http://www.lufft.de/?lang=en&kat=Produkte:Produktsuche&PHPSESSID=0unb160qjocforu6451hq4r577&Suche=byNr&Nr=8510.U050
it is 300 EURO higher than IRS21. It is better than IRS21.
The IRS21 is a "passive" sensor using the parameters measured to provide, among other values, an indication of freeze point depression - the temperature at which the liquid, if any, should freeze taking into consideration the salinity (NACL) of the liquid.
The IRS31 performs the same function, but permits the user to select from up to 10 different "salts", rather than NACL only.
The IRS31 (correcting earlier typo) is certainly "better" for road maintenance organizations using other salts having, for instance, lower freeze point depressions (though typically at significantly higher costs).
* Last updated by: wildmanCSI on 9/18/2008 @ 4:23 PM *