Sharp JX-9400 Informations techniques télécharger pdf (Page 136)

The 2-propanone gas is evaporated in the PAP by placing one or more 30 ml

glass bottles ﬁlled with 10 ml of 2-pr opanone and making diﬀerent holes in the

caps of these bottles. The concentration (in parts per million) of 2-propanone

obtained with one small bottle is about three times the diameter of the hole

in millimetres. Placing one or more bottles enables the production of diﬀerent

2-propanone concentrations. The actual 2-propanone concentrations should be

measured by a suit able calibrated analyser. The position of the small bottles in

the PAP meter is of great importance. Recommended positions are illustrated

in Figure 6.9.

The steady-state concentration of 2-propanone in the top of the diﬀuser

depends on the level of the liquid in the small bottles (which is standardized

at 10ml), the location of the small bottles in the jar of the PAP meter, the

ambient temperature (standardized at 228C), and the size of the holes in the

caps of the small bottles through which the 2-propanone diﬀuses. To get steady

state, it is recommended to condition the whole apparatus and the small bottles

with 2-propanone the day before any test. One hour before the test, place the

bottles in position in the jar, leave the over-caps oﬀ and activate the fan. After

30 minutes a steady-state level with less than 3 per cent variation should be

reached.

The space where the sensory panel is trai ned has to fulﬁl certain criteria.

Preferable is a space that has:

temperature control;

100 per cent outdoor ventilation;

a ﬁltration unit (for example, active carbon);

a Teﬂon layer on walls, ﬂoor and ceiling;

displacement ventilation (from ﬂoor to ceiling) or local exhaust.

Acceptable is a space that is empty (no smoking) and has:

walls, ﬂoor and ceiling covered with a Teﬂon layer or cleaned with a non-

smelling agent;

Bottle

Jar

Fan

Figure 6.9 Recommended locations of small bottles in PAP meter

Source: Bluyssen, 1990.

Contaminants in Air Handling Units 115

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Sharp JX-9400 Informations techniques Page 136