Harmful CMR substances – high burden for plant operators

FRAGOL recommends replacing aromatic hydrocarbons with CMR classification

Aromatic hydrocarbons (AHC) are widely used as heat transfer fluids due to their thermal stability. A well-known example is the substance dibenzyltoluene (DBT), which is used in MARLOTHERM® SH, for example. However, the chemical properties of DBT are highly problematic for humans and nature: The substance is practically not degraded in the environment, is classified as CMR (carcinogenic, mutagenic or toxic to reproduction) and has recently been assigned to the highest water hazard class.

Plant operators who use MARLOTHERM® SH must take a large number of restrictive protective and preventive measures and fulfill extensive labeling and information requirements. The effort for companies is already enormous – and will continue to grow. Anyone looking for a powerful and environmentally friendly alternative to DBT will find what they are looking for at FRAGOL.

Dr Jens Schumacher, who holds a doctorate in chemistry, is an application engineer at FRAGOL and an expert in the regulatory classification of heat transfer fluids. Because harmful aromatic hydrocarbons such as DBT are subject to ever stricter regulations, his customers are also becoming increasingly concerned: "Many are asking what needs to be done specifically – and how they can solve the aromatic hydrocarbon problem in a future-proof manner."

Aromatic hydrocarbons – useful tools of industry

Aromatic hydrocarbons are a group of organic compounds that are used, among other things, as a solvent or precursor for the production of plastics in petrochemistry. They are used as heat transfer fluids in the chemical and pharmaceutical industries, but also in the food industry, for example in baking lines. They "owe" their high popularity to their chemical structure consisting of a planar ring system with conjugated double bonds. Dr Jens Schumacher: "The molecules achieve a particularly high level of thermal stability – ideal conditions for use as a heat transfer fluid in the temperature range of up to around 400 °C."

Dibenzyltoluene: CMR hazardous substance in heat transfer fluids

If it weren't for the extremely critical "dark side" of aromatic hydrocarbons. Many of them are classified as so-called CMR substances. This designation summarizes hazardous substances that are carcinogenic, mutagenic and toxic to classification. The CMR group also includes the aromatic hydrocarbon dibenzyltoluene – the basis of the well-known heat transfer oil MARLOTHERM® SH. 

Within the CMR classification, categories and hazard statements describe the specific hazards that emanate from chemical substances or mixtures. DBT is found in category 1B with characteristics H360FD. In short, the substance is believed to endanger human reproduction by affecting fertility and harming the unborn child.

Classification in the highest water hazard class

Another current development is important for system operators: Based on H360FD, the legislator assigned DBT to the highest water hazard class (WGK) 3 in June 2022. There is a risk that DBT will lead to soil and water contamination in the event of leaks, maintenance work or improper disposal. The substance can also enter the food chain and have long-term effects on animals and humans.

Strictest testing and control obligations
Basically, the following applies: Operators are obliged to assign their systems to a hazard level depending on the oil and oil volume used. This is to ensure that when handling, storing and disposing of heat transfer fluids, the necessary measures are always taken to prevent damage to the environment and human health.

The classification of DBT in the highest water hazard class therefore has consequences, as Dr Jens Schumacher explains: "If, for example, more than 10 m3 of a WGK 3 substance such as MARLOTHERM® SH is used in a heat transfer system, the system must now be assigned to the highest hazard level D. This means that the strictest legal requirements and the tightest test times and intervals apply.”  

High precautionary and documentation effort

Dr Jens Schumacher points out that plant operators who use substances from WGK 3 must draw up an operational water protection concept which, according to Section 44 of the Ordinance on Plants for Handling Water-Hazardous Substances (AwSV), “contains a monitoring, maintenance and emergency plan and immediate measures for against adverse changes in the properties of water bodies.”

As further stated in the ordinance, the operating personnel of the plant must be instructed before starting work and then regularly at appropriate intervals, but at least once a year, on how to behave according to the operating instructions. The implementation of the instruction must be documented by the operator. 

Conclusion of the application technology expert from FRAGOL: “The use of DBT causes a lot of work. A time-, cost- and personnel-intensive undertaking for the plant operator.”

Mandatory test of substitutes

The WGK classification is not only lengthy and tiring for plant operators. It should also create an incentive to consistently replace particularly hazardous substances. In the Ordinance on Hazardous Substances (GefStoffV), the legislature therefore makes a substitution check mandatory and demands the replacement of hazardous substances with substances that are not or less dangerous under the respective conditions of use for the health and safety of employees.

Dr Jens Schumacher emphasizes: "If there are new findings on hazardous material properties, such as the current WGK classification of DBT, the risk assessment of the system must be repeated. And then at the latest, a substitute substance test must also be carried out.”

If the decision is then made in favor of a substitution, customers should use upcoming oil changes, maintenance or refills to keep costs down.”

Alternative high performance products from FRAGOL

FRAGOL offers various mineral oil-based heat transfer media that can very well substitute MARLOTHERM® SH in the temperature range up to 305 °C:

The alternative products from FRAGOL mentioned offer companies numerous advantages that avoid the problematic consequences of using DBT. They are:

  • no CMR substance
  • classified in the lowest WGK 1
  • no dangerous goods and mostly no dangerous substances
  • significantly cheaper

Dr Jens Schumacher is at your disposal for detailed product information and all other questions relating to the exchange of aromatic heat transfer fluids without obligation.

Telephone: +49 (0)208 30002 51
E-mail: j.schumacherfragol.de

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