Weighing and powder handling enclosures provide a safe HEPA-filtered environment for the manipulation of potentially hazardous powders.
Design Features & Performance Criteria
- Weighing and Powder Handling enclosures should be equipped with a true air plenum and exhaust through slots in the rear of the unit. This will create a laminar-like flow and enable capture of fine particulates at their source of generation. hand.
- Powder Handling enclosures should be equipped with a “downstream” HEPA (High Efficiency Particulate Arrestor) filter in the exhaust line to capture particles.
- Such enclosures should feature air foils or curved edges around the front opening to reduce the turbulence created by moving air.
- Cleaning of enclosure systems should be safe: The design should allow the scientist to easily reach all internal areas of the unit without opening extra panels or doors.
- Surfaces within the system should be smooth to minimize concentration of powders in corners and gaps.
- The base must be integral to the system, this ensures that if the system is moved no contamination is left behind, in addition the base should be recessed in order to contain any liquid spillage and prevent sample vials rolling off.
- Recommended face velocities for open-faced ventilated enclosures should be between 0.30 to 0.45 m/s (65 to 90 fpm). Lower face velocities reduce vibration and allow sensitive balances to operated effectively.
- The velocity profile should have a uniformity of ±20% of specified design air velocity at all points of the enclosure opening. This performance must be verified on site and documented by the commissioning engineer.
- Airflow condition must be monitored at all times and an audible/visual alarm activated in the event airflow profile fails.
- Extract points from HEPA filters can be connected to the general laboratory exhaust system via a thimble connection or similar device that prevents the exhaust and extract system ‘competing’ with each other.
- Dependent on the risk assessment of the drugs being handled, a double HEPA system can be recommended for recirculation, this makes available a secondary filter should the primary filter drop in capture efficiency.
- Yearly filter integrity and system checks are to be made to ensure the filters are performing to the correct efficiency.
Positioning of Weighing and Powder Handling Enclosures
- Similar to laboratory fume hoods, ventilated balance enclosures and powder handling hoods should not be located near doorways, in high traffic areas, at right angles to each other or in remote corners of the lab against a wall that may impede the flow of supply air.
CTS are the recognise market leader for laboratory safe weighing environments and their ST1 potent powder balance enclosure is used by major pharmaceutical laboratories worldwide.
Find out more information on CTS Potent Powder Weighing Enclosures.
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