I am facing a problem at one of my clients ..... they require one 30 TR plant @ -25 and another of 25 TR @ -30 degree celcius.
One manufacturer has suggested to them that they that they use MEG , but in our systems we use Propylene Glycol ....
now the problem is that some manufacturers suggest them Propylene Glycol while others suggest MEG ...to further add to their dilemma one hand book( Perry's suggests Use of MEG and not Propylene Glycol ) at such low temp......while the other hand book (author i dont remember) suggests use of Propylene glycol....!

our experience has been using Propylene glycol ( we use them for Soap Stamping M/c's which require liquid @ -30 degree celcius )
NOW , WHAT actually is the basis ? how to suggest which glycol or liquid mixture is suitable for which condition ?

kindly suggest wt to do ?

dchatta