If the performance charts are used

If the performance charts are used to plot the operating points of adjustable fans (see Figure 2), then the limit deviations as specified in Table 2 apply only to the specified tolerance zones. For nonadjustable fans, see Figure 3. The specified operating points shall be deemed as having been reached if the measured values (including scatter) fall within, or just touch, the tolerance zone specified for the relevant parameter, which is a function of the selected accuracy class (see Figure 4). By way of example, the boundary of the performance chart may coincide with part of a characteristic, which is the case for a fan having adjustable rotational speeds (see Figure 2). Figure 5 then shows the range of measured values against the specified characteristic (with the limit deviations being indicated as a function of the agreed accuracy class).