RCP measurement with GSA measuring device SG350ex

With the measuring device SG350ex, the mass fractions of hydrocarbons can be determined by means of an RCP measurement. The measurement with the measuring device SG350ex is used to check occupational health and safety. It can be used to test whether the permissible occupational limit values of the respective mixtures are exceeded or whether there is no specific health hazard.


Definition of RCP

The abbreviation RCP stands for the description of the measurement method: reciprocal calculation procedure. It is a measurement and calculation procedure that determines the occupational limit value of various hydrocarbon mixtures. determined.

Regularly checking compliance with limit values is an important aspect of occupational safety and employee protection.

What is determined during the RCP measurement?

Hydrocarbon mixtures are listed in the REACH Regulation as so-called“UVBC substances“, i.e. substances whose composition is variable or unknown – “complex reaction products or biological materials”.

As can be deduced from the name, these compounds consist of carbon (C) and hydrogen (H). These compounds include aliphatics and aromatics.

Among aliphatics are compounds that are lipophilic (fat-soluble) and non-polar. They are not aromatic and can consist of saturated (C-C single bond), unsaturated (C-C double bond) and cyclic hydrocarbons and thus form the opposite of aromatic carbon compounds. Examples of such compounds are C2H2 (ethyne, acetylene) or C3H8 (propane).

Why is an RCP measurement carried out?

As the health risk of mixtures cannot be attributed to one substance, another solution must be found. Therefore, the composition of the hydrocarbon mixtures is determined in order to determine the occupationalto be able to calculate theoccupational exposure limit value (OEL).

These hydrocarbon mixtures are therefore divided into three categories in TRGS 900:

  • C6-C8 Aliphates limit values: 700mg/m³
  • C9-C14 Aliphates limit values: 300mg/m³
  • C9-C14 Aromatics Limit values: 50mg/m³

These limit values are the results of numerous studies and data collections with regard to the hazard potential of individual substances contained in the mixtures.

What health hazards do substance mixtures pose?

As these are mixtures of substances, it is not possible to assess a general hazard.

RCP measurement is therefore an important tool in the field of occupational health and safety.
The symptoms of exposure are as numerous as the substances involved. They range from headaches (e.g. with cyclohexane) to respiratory irritation (e.g. with cumene). There are some substances that are included in the calculation with their own OEL. These include, for example, cyclohexane (C6H12) and n-hexane (C6H14). There are also substances that are not included in the calculation despite having their own limit values, such as toluene (C7H8) or ethylbenzene (C8H10).

RCP formula: Calculation of the limit values

Using the RCP formula, the limit values can be determined after analyzing the substance mixture. To do this, the fractions (mass fractions in the solvent mixture) and the group limit values or individual values are entered and the occupational limit value for the hydrocarbon mixture can be calculated from this.


Sources:
[1]: https://www.gischem.de/e1_allgm/glossar-item.htm?view_Glossarliste_OID=106
[2]: https://www.dguv.de/ifa/praxishilfen/praxishilfen-gefahrstoffe/software-arbeitsplatzgrenzwerte-fuer-kohlenwasserstoffgemische/index.jsp
[3]: https://www.baua.de/DE/Angebote/Rechtstexte-und-Technische-Regeln/Regelwerk/TRGS/pdf/900/900-kohlenwasserstoffgemische.pdf?__blob=publicationFile&v=3
[4]: https://www.arbeitssicherheit.de/schriften/dokument/0%3A163371%2C3.html
[5]: https://www.bgrci.de/fileadmin/BGRCI/Downloads/DL_Praevention/Fachwissen/Gefahrstoffe/Analytik_Symposium_2018/Vortr%C3%A4ge_2018/Pflaumbaum_Symposium_2018.pdf
[6]: https://www.dguv.de/medien/ifa/de/pra/kss/messverfahren_rcp-methode.pdf
[7]: https://www.dguv.de/medien/ifa/de/pra/softwa/rcp/anwendung_rcp_rechner.pdf