§ 627.55 - Ventilated balance enclosures.

(a) Description. A ventilated balance enclosure is a box that surrounds a balance and has a small open area for access and handling material in the front. Air is exhausted out the rear of the enclosure.

(b) Uses. A ventilated balance enclosure is used when containment of a balance is required to weigh hazardous materials that have a low vapor pressure (such as toxins). These enclosures are also used when it is best to use the balance in other than a fume hood (due to the turbulence and vibration) and when biological safety cabinets or glove boxes are inappropriate or unavailable. Dry forms of toxins may be weighed in these enclosures.

(c) Prohibitions. Very volatile or highly toxic volatile materials must not be handled in ventilated balance enclosures unless they are placed in closed containers in a properly functioning fume hood before being transferred to the balance enclosure.

(d) Additional certifications or requirements. (1) The flow through the openings in the enclosure will be at least 60 lfpm and must average between 60 and 80 lfpm.

(2) Containment will be certified prior to first use and annually thereafter by smoke tubes.

(3) The air flow will be certified initially and semiannually by averaging readings taken from the face of the opening.