Differences between glycol-based fluids.
Differences in terms of environmental aspects
-monopropylene glycol (MPG):
When your priority is the safe operation of the system, you should consider using a solution that is based on environmentally friendly monopropylene glycol. Such a medium is most commonly used in systems where there is a risk of release of the fluid and contamination of food or soil. To highlight the environmental friendliness of the fluid, manufacturers usually dye it green. Some global manufacturers produce colourless fluids, but the National Institute of Hygiene recommends dyeing them to reduce the risk of accidental ingestion.
As a raw material, propylene glycol is considered a harmless or nearly harmless compound. Accidental ingestion does not pose a risk to health or life. However, the content of propylene glycol is not the only aspect that determines whether a given fluid is safe or not. All other additives should also be environmentally friendly. A safe fluid should have no hazard warning pictograms in its safety data sheet. When choosing a product, it is also recommended to take into account any relevant approvals, such as PZH hygienic approval. Such documents must be valid, as they are usually issued for a period of 3-5 years.
-monoethylene glycol (MEG):
Fluids based on monoethylene glycol are highly toxic. They are used in systems where there is no direct contact with food or there is no risk of release into the soil. MEG causes acute poisoning or even death if ingested.
Manufacturers usually dye these types of fluids blue. Until the beginning of 2015, it was possible to apply for PZH hygienic approval for this type of fluids. However, due to changes in regulations and the high toxicity of monoethylene glycol, the National Institute of Hygiene has discontinued the certification process of industrial fluids containing MEG.
Application due to environmental reasons: solar panels, heat pumps, installations used in the food industry.
Physical and chemical differences between monoethylene glycol (MEG) and monopropylene glycol (MPG)
In addition to environmental aspects, fluids based on MEG and MPG also differ considerably in terms of their physical and chemical properties. These differences have a significant impact on the system’s performance, energy efficiency and operating conditions.
The most important factor that determines the choice of a suitable fluid are the operating parameters of the system. In large systems with low operating temperatures, monoethylene glycol-based fluids are preferred due to their lower viscosity, which allows to cut down the costs of running the pump and operating the system.
In the case of systems (e.g. solar panels) which require heat transfer medium with a higher thermal capacity, monopropylene glycol-based fluids are a better choice, as they allow to optimise the operation of the solar installation, making it more efficient. The physical and chemical differences of various types of fluids are significant. Selection of the most suitable medium, based on its physical and chemical properties, is a key to efficient, smooth and trouble-free operation of the system.
The table below shows the differences in the basic physical and chemical properties of MEG-based and MPG-based fluids at a temperature of -25°C. It shows values at different operating temperatures.
Factory -25°C (based on 40% monoethylene glycol MEG)
Factory EKO -25°C (based on 42% monopropylene glycol MPG)
For comparison purposes, the tables show only the basic parameters of the glycols in one temperature option. You can contact us for detailed parameters in other temperatures.
Differences in physical and chemical properties can significantly alter the performance of a system. We know from our customers’ experience that replacing one type of glycol with another often leads to better efficiency of the system.
Origin of different types of glycols.
Currently, antifreeze manufacturers have a very wide range of glycols to choose from, derived from different processes. The glycols that are currently available on the market come from the following sources:
Monoethylene glycol (MEG) and monopropylene glycol (MPG) are also obtained as a by-product of fuel production. An example of a Polish supplier of MEG is PKN Orlen. The company is planning to set up a plant for the production of monopropylene glycol as well. The raw materials derived from refinery processes are characterised by a very good quality and high purity, and are, therefore, the first choice of manufacturers who want to ensure high quality of their products.
Glycols from regeneration processes are also available on the market. Dirty, burnt and often used fluids are subjected to filtration and distillation processes in order to obtain regenerated glycol.
These raw materials are of poor quality, but are chosen due to their low price. Usually, such raw materials are mixed with several types of glycol and contaminated with various elements. They often have an unpleasant smell, similar to that of used engine oil.
Production of antifreeze fluids based on regenerated raw materials may cause product delamination, unpleasant odour from the system, precipitation of deposits and the need to replace the fluid very often.
To see whether a fluid is based on regenerated raw material, one should check the warranty period offered by the manufacturer. Typically, the warranty period should be up to 5 years. Unfortunately, on the Polish market there are a lot of products based on regenerated raw material. Most often they are much cheaper and their quality leaves much to be desired.
Unlike monoethylene glycol (MEG), monopropylene glycol (MPG) can also be derived from plants (e.g. corn or rapeseed) in a fermentation process. This type of raw material is used less frequently in the production of antifreeze due to its higher price compared to glycol derived from refinery processes.
Prices of MEG and MPG glycols. Why do they differ?
Often when choosing a suitable fluid for a system, its price is an important factor. Customers often ask for the cheaper alternative without taking into account the properties and quality of the product. Fluids based on monopropylene glycol (MPG) tend to be about 30% more expensive than those based on monoethylene glycol (MEG). This is due to the fact that they use an environmentally friendly and completely safe raw material, the market price of which is much higher.
Often various manufacturers offer fluids based on glycols of the same type, which, for some reason, differ in price.
Such differences are due to the different additives and the origin of the raw materials. Fluids based on regenerated glycols and additives, with a short shelf life (e.g. 2 years) will logically be cheaper than those with a longer shelf life of up to 10 years.
To sum up, choosing glycols can be compared to choosing a light bulb. If you buy a cheaper one, it will burn out within a few months. However, if you opt for a more expensive alternative, it will serve you for years.
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