Glycol soutions and applications

[cme]

I would like some input on using inhibited ethylene glycol solutions vs inhibited polypropylene solutions for freeze protection. What type buildings would you apply ethylene glycol or not and why.

 

[pennpoint]

cme
Simply stated: Ethylene Glycol is toxic and Polypropylene glycol is not toxic. It depends upon your application.
Do a search to find the diffrence and the benifits of either product.

pennpoint

 

[wilg]

Ethylene Glycol :
as pennpoint states, Ethylene Glycol has a High Toxicity,
targets the kidneys

Ethylene Glycol has a more effective freeze point
depression than propylene Glycol
at 30% solution Ethylene Glycol freeze point is 4 deg F
at 30% solution propylene Glycol freeze point is 8 deg F

Ethylene Glycol heat transfer properties are better
than propylene Glycol

Ethylene Glycol has a lower viscosity than propylene Glycol
(propylene Glycol looks like a thick sludge when
you drain the system)

Ethylene Glycol bio-degradation occurs in a shorter time
than propylene Glycol

suggest that you insist on a dye to be incorporated with
the antifreeze to detect leaks.

make sure that you have corrosion inhibitors and spec
no silicate content, silicates are usually found in
automobile antifreeze.

size your expansion tank to be about two-thirds full
during normal operation...Glycol will expand about
6% during normal operation.

Use a low level alarm in lieu of automatic makeup,
this will prevent system dilution.

Do annual chemical checks of system, on a PM basis.

Watch for foaming in the system as this indicates
air entrainment.

 

[cme]

I had a discussion with a local engineer about freeze protection for school projects. He told me without explanation that their standard is propylene glycol. I would like some input on why not use ethylene glycol.

 

[Cooky]

In my view, ethylene glycol should be used for all commercial and industrial applications and propylene glycol should be used for applications in the food industry.

I can confirm what wilg has said about the comparative properties of the different glycols. From a thermophysical point of view, ethylene glycol gives higher rates of heat transfer, it has a higher specific heat capacity and requires less electrical power to drive the water circulation pump.

From an environmental perspective, ethylene glycol should not be allowed to enter surface water drains (as opposed to foul water drains), due to its toxic properties. I was interested to note wilg's comment about ethylene glycol degrading faster than propylene glycol.

Personally, I would use ethylene glycol for a school system. Ethylene glycol has a very very sweet taste, and I could not imagine anyone knowingly drink the liquid.

Although, I suppose it could be absorbed through the skin, does anybody know if this is possible?