PDA

View Full Version : which glycol to use ?







dchatta
10-07-2004, 08:18 AM
I am facing a problem :confused: 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

chemi-cool
10-07-2004, 11:55 AM
There must be some logic behind everything you do.

If you are used to work with propylene glycol and know how to handle it and have the knowledge to setup the refrigeration system, you can supply your client the best.

I don't see any reason to go to something different unless it is much better.

I would discuss it with the client and explain all the pro`s and con`s.

Chemi

mcamacho
11-07-2004, 04:24 AM
I do not have the information at hand, but the main issues to consider with glycols are initial cost and pumping cost. Glycols' viscosity increases rapidly as pressure drops. Maybe the other substance has lower viscosity at same temperature.

-Manuel.

dchatta
12-07-2004, 06:38 AM
I do not have the information at hand, but the main issues to consider with glycols are initial cost and pumping cost. Glycols' viscosity increases rapidly as pressure drops. Maybe the other substance has lower viscosity at same temperature.

-Manuel.

u probably a r rt, even I was thinking on same lines but for want of some thing concrete!

i had a look a Dow's literature (on line ) ... propylene has higher specific Heat , low thermal conductivity, lower Density as compared to MEG(ethylene glycol)...
also Dow Software for Glycol selection throws up both options for the kind of application I was seeking( Glycol temperature of -30 degrees)

CDF
12-07-2004, 09:26 AM
I am somewhat confused. You seem to be discussing which Glycol to use between MEG and MPG around its density and thermal conductivity. The first thing to consider is does the system have to be Food safe or industrial (non food safe). MEG does have a lower viscosity however is obviously only suitable for non food applications. If your application is non food then MEG IS the only answer as otherwise you will be paying for a product that is not required, as you will require more MPG than MEG to reach the same temperature protection. All glycol products however are NOT the same in terms of protection you should refer to the manufactureres technical specifications to ensure you have the correct % in your system for the correct protection.The better products will also have corrosion and scale inhibitor's.

If you require a good glycol product let me know!!

Hope this helps.