An aqueous solution of propylene glycol

A propylene glycol solution is a mixture of propylene glycol and distilled water.
The higher the concentration of propylene glycol, the lower the initial crystallisation temperature becomes. However, at the same time, the solution becomes more viscous.
Therefore, the concentration should be selected based on the actual minimum temperature, rather than on the principle of ‘the higher, the better’.
For solutions produced by AO Khimprom Ltd, the concentration is specified as a percentage by mass.
For example:
40 % = 40 kg of propylene glycol + 60 kg of distilled water per 100 kg of finished solution.

Table 1.
Freezing point and density of propylene glycol aqueous solutions.

What does the crystallisation onset temperature mean?

This is the temperature at which the first crystals begin to form in the solution.
This does not mean that the entire solution freezes immediately.
As the solution cools further, it becomes thicker, and circulation within the system becomes more difficult.
Therefore, the operating temperature must be set at a margin above the crystallisation onset temperature.

Why you should not choose the maximum concentration

A higher concentration lowers the crystallisation onset temperature, but it also:
• increases viscosity;
• puts more strain on the pump;
• alters the thermophysical properties;
• may impair circulation at low temperatures.
The optimum concentration is not the maximum, but the level sufficient for your temperature conditions.

Propylene glycol solution or ready-to-use heat transfer fluid

These are different products.
Propylene glycol solution
Composition:
propylene glycol + distilled water.
Contains no anti-corrosion, anti-foaming or other functional additives.
This product is used:
• as a raw material;
• as a component in the production process;
• for in-house formulations;
• in equipment that permits the use of an aqueous propylene glycol solution without additives.
AO Khimprom LLC can manufacture solutions of various concentrations.

Ready-to-use heat transfer fluid
Ready-to-use heat transfer fluid contains not only propylene glycol and water, but also a functional additive package.
In the ‘Novokhim’ range, these are the FREEZLIGHT® heat transfer fluids.
If the system requires corrosion protection and other functional properties, it is necessary to choose a ready-to-use heat transfer fluid rather than a standard propylene glycol solution.
Can a standard solution be used in a heating system?
Only if the equipment manufacturer and the system design permit the use of an aqueous propylene glycol solution without additives.
Propylene glycol on its own does not replace an anti-corrosion additive package.
For systems requiring an inhibited heat transfer fluid, it is better to use a ready-to-use product with the appropriate additives.

What to bear in mind before filling

Before filling the system, it is important to:
1. Know the required concentration.
2. Remove as much residual water as possible.
3. Check the equipment manufacturer’s specifications.
4. Take the system materials into account.
5. Check whether the solution’s viscosity is suitable for the pump.
Residual water reduces the actual concentration after filling.

Common mistakes

40 % = −30 °C.
No. For 40 % by mass, the approximate crystallisation start temperature is around −22 °C.
The more propylene glycol, the better.
No. Viscosity increases as the concentration rises.
Standard solution = ready-to-use heat transfer fluid.
No. A standard solution does not contain any functional additives.
The water remaining in the system can be disregarded.
No. It dilutes the ready-to-use solution.

How to choose

If you require a specific concentration without additives, choose an aqueous propylene glycol solution.
If you require a ready-to-use working fluid for a heating or cooling system with a functional additive package, choose FREEZLIGHT®.
If you require a different concentration, AO Khimprom LLC can manufacture it to order.

Related products
• 40% propylene glycol solution without additives
• Concentrated propylene glycol
• FREEZLIGHT® −20 °C, propylene glycol-based
• FREEZLIGHT® −32 °C, propylene glycol-based

Where to buy propylene glycol solution

At ‘Novokhim’, you can purchase a ready-made 40% propylene glycol solution in distilled water without functional additives.
It is also possible to produce aqueous propylene glycol solutions of other concentrations to order.
If you require not a standard solution but a ready-to-use heat transfer fluid with a functional additive package, the catalogue features FREEZLIGHT® −20 °C and FREEZLIGHT® −32 °C, both propylene glycol-based.
To prepare a solution of the required concentration yourself, you can purchase concentrated propylene glycol

Click on the link and choose your heating solution:

based on propylene glycol

glycerin

ethylene glycol based

FAQ

What does 40% mean?
40% by mass means 40 kg of propylene glycol and 60 kg of distilled water in 100 kg of the finished solution.
What is the crystallisation onset temperature of a 40% solution?
Approximately −22 °C.
Can I order a different concentration?
Yes. We can produce solutions of various concentrations.
Do these solutions contain anti-corrosion additives?
No. They consist of propylene glycol and distilled water.
How do they differ from FREEZLIGHT®?
FREEZLIGHT® contains a functional additive package and is a ready-to-use heat transfer fluid for the relevant systems.