Conditions of use : The weighing booth is used for the containment of volatile powders during the loading, weighing, and transfer operations ; and for the preparation of doses to be incorporated into solutions for the manufacturing of batches. Working principle : The weighing area is protected by a vertical laminar air flow class ISO 5 (NF, EN, ISO 14644-1), with a partial air recycling. A combination of two air flows : one that is blowing ultra clean aire into the surrounding room from one extremity of the blowing plenum (10% air bleed) via a grille at the front of the booth ; and the other that is sucking and recirculating the air of the weighing area ; create together a negative pressure within the weighing area (compared to the surrounding room), thus avoiding any cross contamination. Construction : The weighing booth is composed of 3 parts: a blowing plenum, equipped with the HEPA filters, perfectly airtight to the EMERY test; a recirculation duct, which holds the prefilters; and a ventilation plenum, located beside the blowing plenum, and upside the recirculation duct, which holds the ventilation fan, and blows the air into the blowing plenum. The blowing plenum is suspended to the structures on the frontside, resting against the ventilation plenum. The weighing area is equipped with a weighing table.