Table 1 – ISO Classes of Air Cleanliness by particle concentration
|ISE Class Number (N)||Maximum Allowable concentrations (particles/m3) for particles equal to and greater than the considered sizes, shown belowa|
|0,1 μm||0,2 μm||0,3 μm||0,5 μm||1 μm||5 μm|
|5||100,000||23,700||10,200||3,520||832||d, e, f|
- a All concentrations in the table cumulative, e.g. for ISO Class 5, the 10,2000 particles show at 0,3 μm include all particles equal to and greater than this size.
- b These concentrations will lead to large air sample volumes for classification. Sequential sampling procedure may be applied; see Annex D.
- c Concentration limits are no applicable in this region of the table due to very high particle concentration.
- d Sampling and statistical limitations for particles in low concentrations make classification inappropriate.
- e Sample collection limitations for both particles in low concentrations and sizes greater than 1 μm make classification at this particle size inappropriate, due to potential particle losses in the sampling system.
- f In order to specify this particle size in association with ISO Class 5, the macroparticle descriptor M may be adapted and used in conjunction with at least one other particle size. (See C.7.)
- g This class is only applicable for the in-operation state.