Laboratory safety equipment and enclosure manufacturer Bigneat Ltd manufactures a range of HEPA filtration safety cabinets for user protection for up to OE level 5.
There are four ranges to choose from and your choice will be influenced by the precision of the weighing you wish to undertake. The compact ‘F3-XIT’ is suitable for weighing on a precision balance to three decimal places, however if you wish to weigh on an analytical balance then you will need to consider the ‘XIT Plus’ Weighing Station.
The key to being able to weigh with minimal fluctuation is down to two factors, the quality of the airflow in the cabinet and the positioning of the cabinet away from fluctuation causing factors such as doors, windows, people traffic and building vibration.
Bigneat’s cabinets are designed to provide suitable face velocity at the front of the cabinet at between 0.3 and 0.5m/s depending on the application, the flow needs to be as low as possible yet with the ability to contain the airborne particle within the cabinet enclosure and carry it away into the HEPA particulate filter. Bigneat fans have the added benefit of being energy efficient and quiet.
For micro-balance weighing the user will be requiring five or six decimal places. Bigneat offers the ‘Excel Plus’ range which incorporates aerofoil technology and a graded rear back baffle which together reduce air turbulence and smooths the air flow across the width of the work surface.
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A ‘Safechange’ version of the Excel Plus is designed to enable the removal of HEPA particulate filters when required under negative pressure within the cabinet ensuring no powder is released into the fan housing or downstream into ductwork.
This latter cabinet has been thoroughly tested and validated using lactose powder as a tracer agent in repetitive tests designed to simulate real use of the cabinet. There was no detectable breakthrough of any lactose particles during testing. Details of the test are available on request.
Bigneat manufactures bespoke cabinets on request and manufactures all its products in Britain.
VIDEO: See powder handling & weighing in action: