ISO 11943:2021 pdf download – Hydraulic fluid power- Onlineautomatic particle-counting systems for liquids – Methods of calibration and validation
ISO 11943:2021 pdf download – Hydraulic fluid power- Onlineautomatic particle-counting systems for liquids – Methods of calibration and validation.
9.5 lIthe particle counts obtained in 9,3 are outside the limits set, take corrective action and repeat the verification procedure described in 9,1 through 9A.
a) the proper sensor Ilowrate Is being used;
b) the particle size threshold settings are correct;
c) the fluid is completely degassed;
d) the sample weights and volumes are correct;
e if interpolation olthreshold settings between verified points Is required, the Iso 11171 method of interpolation shall be used. Extrapolation may not be used.
10 Matching of two or more particle counters
10.1 This procedure shall be used when two or more APCs are to be used upstream and downstream of a filter to measure its filtration efficiency at various sizes.
NOTE The ‘master’ system (sensor 1) in the matching process is the system with the higher signal to noise ratio. This allows the ‘slave’ sensor (sensor 2) a wider matching range.
10.2 In itself, this procedure is not suited to performing or verifying the calibration of one of the two instruments. For calibration refer to Clause 7: for online calibration refer to Clause 9.
10.3 Connect the APC calibrated in accordance with Clause 9 (online calibration) and another one to be matched to the sampling points described in £5 ala closed 1oop system validated in accordance with Clause 8.
The two instruments shall match together without using the dilution system.
10.4 Set the instruments to the cumulative mode and to at least six different threshold settings over the particle size range of interest.
105 Adjust total fluid volume, expressed in L in the hydraulic test equipment to the desired level and measure within *1 %. Maintain fluid viscosity at (15 ± 2,0) mm2/s. The concentration of particles at any size should be statistically significant and particle counts should beat any sIze >10.
10.6 CIrculate the fluid through the clean-up filter until the fluid contamination level is c S particles>
10.7 Determine the ISO MTD concentration to be used for the matching so that the maximum particle count at the lowest particle size can be approximately 75 % of the APC coincidence error limits determined In 72. Prepare In accordance with £3. Record the ISO MTD batch/lot number
10.8 Bypass the clean-up filter, add the contaminant to the reservoir and mix by circulation for about 15 mm or until the counts have stabilized across the size range.
10.9 Start the APC matching procedure by conducting online automatic counts at 1-mm intervals for a period of at least 30 min.
11 Validation of an online dilution and particle counting system
11.1 Perform a validation of the online dilution system, where used, at the same frequency as calibration verification. The procedure Is described In Fiui-e2.
11.2 Use dilution fluid which has been filtered to a cleanliness level of < S particles> S pm(c) per ml, unless it can be established that a higher level does not add more than 1 % error to the resulting particle counts.
11.3 Validate first at the minimum dilution factor to be used.
11.4 Circulate the fluid through the clean-up filter until the fluid contamination level is c 5 particles> S iam(c) per mL
11.5 Prepare an ISO MTD secondary calibration suspension In accordance with &1 to 8.6 but at a level equal to (75 t 10) % of the concentration limits in 72. multiplied by the dilution factor selected. Record the batch number of ISO MTD.
EXAMPLE For a two times dilution factor (1 part diluent: I part suspension), use a sample concentration equal to 2 times 75% olthc counter concentration limit.
11.6 Bypass the clean•up filter, add the contaminant to the reservoir and mix by circulation for about
15 mm or until the counts have stabilized across the size range, whichever occurs first.
11,7 Set the particle counter at a minimum of six particle size threshold settings covering the range 0 interest.
11.8 Using the dilution factor selected, obtain a minimum of three 25 ml particle counts (after the counts have been stabilized) for each sensor and calculate the average count of the diluted sample for each partide size.
11.9 Calculate the average counts per mL for each particle size threshold setting dividing the average count by the fluid volume counted in ml. Record the values in Table 6. Use separate data sheets for both sensors 1 and 2 where used.
11.10 All particle counts obtained In 11.7 should be equal to the reference counts, ± the calibration limits in column 3 of Table3, (or each particle size counted. In addition, when sensors land 2 are being used the average counts from the two counters (sensors) shall agree within the allowable variation given in 10,10, for each particle size counted.
11.11 Repeat the procedures giveli In 11.4 to 11.10 at the maximum dilution factor to be used and at least two other intermediate dilution factors within the total dilution range of the system. It is recommended that the most common dilution ratios that will be used for the equipment be checked as described in this clause.