The following sampling systems are available in the GSA for the sampling of MWF:
- SG10-2 with PGP GGP3.5 (personal sampling)
- SG5100ex with PGP GGP3.5 (person-carried sampling)
Personal and stationary sampling is usually carried out with SG10-2 and PGP GGP3.5 or with SG5100ex with PGP GGP3.5.
The dust-laden air is sucked in with a battery-operated pump (SG-10-2) with a volume flow of 3.5 l/min (210 l/h). We recommend a measurement duration of at least 2 h, so that a volume of 0.42 m³ is reached in order to be able to detect 1/10 of the limit value (10 mg/m³). The air loaded with cooling lubricants flows through a membrane filter, a binder-free glass fibre filter with 37 mm diameter, on which the oil mist / aerosols are separated. In addition, a cartridge filled with 3 g XAD on which the oil vapours are separated.
- FTIR-Spectrometer Spectrum TWO and Spectrum 100 by Perkin Elmer
Preparation of the sampling system for analysis
The membrane filter, a binder-free glass fibre filter of 37 mm diameter and the 3 g XAD are wetted with 10 ml tetrachloroethylene for 16 h in order to transfer, i.e. to extract the fraction of cooling lubricants into the tetrachloroethylene.
A glass fibre filter (binder-free) with a diameter of 37 mm is used as the collection phase to collect the aerosols, and 3 g XAD-2, grain size 0.5 – 0.9 mm, is used downstream to collect the vapour phase.
To determine the concentration of cooling lubricants, the glass fibre filter and the XAD-2 are transferred separately into sealable glass vessels. Then covered with 10 ml of tetrachloroethene and left sealed at room temperature for 16 hours. The filtrate is then filtered and transferred to a quartz cuvette.
The analysis is carried out with an FT-IR spectrometer, model Spektrum 100 by Perkin Elmer, with a resolution of 2 cm-1 and 20-fold spectra addition. After subtraction of the solvent spectrum, the range of aliphatic CH valence vibrations from 2800 cm-1 to 3000 cm-1 is integrated.
Calibration is carried out according to the standard calibration method with solutions of the substance used at the sampling location. The mass concentration is calculated by dividing the mass found by the sample volume.
Assessment standard according to DGUV 109-003.
At present, the current technical rules for hazardous substances TRGS 900 do not specify a valid occupational exposure limit for “cooling lubricants”.
DGUV Regulation 109-003 (Activities involving cooling lubricants, previously (BGR/GUV-R 143) does, however, specify an assessment standard for activities involving cooling lubricants. This defines the upper limit for MWF concentrations in the air breathed for the cases which apply here:
– Non-water-miscible cooling lubricants with a flash point > 100 °C in metalworking
– Water-miscible cooling lubricants for metalworking and for glass and ceramics processing, water-miscible and water-mixed forming lubricants are fixed at 10 mg/m³.
This concentration of cooling lubricants in the air in working areas is achievable according to the current state of the art in the industries and areas concerned. If the concentrations fall below this level, it can be assumed that no further measures are necessary in accordance with the graduated concept (see DGUV Regulation 109-003 Section 6.3.3).