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mechanical air supply with ﬁltered air;

mixing ventilation with a certai n minimum ventilation rate.

During the tests, the background level of 2-propanone should not be more than

1 ppm.

Five diﬀerent 2-propanone concentrations generated by ﬁve PAP meters

are used as milestones for the training. These milestones have PAP values

corresponding to the concentrations in Table 6.1 of 2-propanone in the top

of the cone.

The equation for calculating the values is:

PAP value ¼ 0:84 þ 0:22  2  propanone concentration (ppm) ð6:1Þ

Once the milestones are calibrated, it is important to keep the same PAP meters

with the same bottles at the same lo cations in the jar, since chang ing these para-

meters may change the 2-propanone concentration in the cone.

For selecting the pan el, eight additional PAP meters with ﬁve concentra-

tions ranging from 0–40 ppm and three with 5–90 ppm are prepared. The appli-

cants are asked to assess these eight diﬀerent concentrations of 2-propanone

using the milestones as the reference. They will be instructed to have at least

two inhalations of unpolluted air in between each PAP sniﬀ. The question

asked of the applicants is:

How strong is the air that you perceive? Give a number on a scale from 1

to 20, but refer this number always to the numbers on the milestones 1, 2,

5, 10 and 20. One is equal to no smell (you perceive nothing), 20 is equal

to extreme strong smell.

The app licants are allowed to go back and forth between the eight diﬀerent

unknown concentrations and the milestones as much as they need, and note

the given value for each unknown PAP me ter. The dozen subjects with the

least sum of diﬀerences between given and actual values are selected.

Training procedure

The 12–15 sub jects are trained for three to ﬁve days in smaller groups of three

or four people. Each day, they receive approximately one hour of intensive

training. In the ﬁrst two days, the panel is trained to assess perceived air

Table 6.1 PAP values and 2-propanone concen-

trations in PAP meters used as milestones

Value Concentration [ppm]

1 (no odour) <1

519

10 42

20 87

116 Ventilation and Airﬂow in Buildings

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Sharp JX-9400 Informations techniques Page 137