The comparative measurement is performed by using a secondary calibration solution.
The calibration of particle counters is divided into primary and secondary calibration.
Primary calibration is performed in accordance with ISO11171, which defines standards-compliant procedures for the calibration of particle counters for the contamination analysis of hydraulic fluids. These procedures use a defined test dust traceable to NIST SRM 2806B, which is suspended in purified mineral oil. The suspension is then analysed by means of an electron microscope. This ensures that the particle-size distribution of the reference dust actually complies to the required standards. In the given oil circuit, the reference device is then calibrated in a traceable manner.
The calibration of our oil particle monitor is performed following ISO11943. The secondary calibration is performed on the basis of the defined test dust from the primary calibration. During this procedure, purified mineral oil is again mixed with a defined amount of test dust. The suspension is then analysed with the device under test, i.e. the oil particle monitor, and the primarily calibrated reference sensor before the results are compared.
The calibration is performed on the basis of 4 measuring channels and indicates the exact particle-size distribution on 4, 6, 14 and 21 µm of the secondary calibration suspension.