MP Filtri LPA2, User Manual

Page: 56 / 72

Appendix G
56 New ISO Medium Test Dust and its effect on ISO . . .
To clarify matters still further, ISO standards written around the new test dust
will utilize a new identifier, ‘(c)’. Hence µm sizes according to the new ISO
11171 will be expresses as ‘µm(c)’ and Beta ratios according to ISO 16889
will be expressed as ‘Bx(c)’, e.g.‘B5(c)’.
However, it must be stressed that the only real effect users will experience
will be the improved accuracy in particle counts - there will be no change
in the performance of filters, nor in the ISO cleanliness levels that they will
achieve.
The following charts shows the correlation between the old ACFTD and the
new ISO MTD.
The LPA² is calibrated with ISO Medium Test Dust (to ISO 11171). The
correlation between particle sizes and the ACFTD (old standard) to the ISO
MTD (new standard) is as follows :
ACFTD <1 5 15 25 30 50 75 100
ISO MTD 4 6 14 21 25 38 50
XI
70
XII
XI
Not verified by NIST
XII
acftd