Powder Units

Powder units

• Clean work station for weighing of raw material and taking samples of it
• Protects also the operator and environment
• Filtration in two, three or four steps
• Dimensions and materials according to the customer’s needs
• Several options to choose:
  – light fixtures
  – half speed function
  – side walls or curtains
  – velocity gauge and alarm functions
  – fresh air connection
  – built-in cooling or heating element
  – interlocking with general ventilation
• Air curtain can be included to ensure free entrance to the working area

Function

Air recirculates in the module normally through 3 set of filters. Air circulates through grilles close to the floor in the back wall of work chamber. The first filtering step is after the grilles. Class of filters is EU3 – EU5. Biggest part of visible particles are filtered in this step. The next filtering step is EU6 – EU9 where rest of the visible particles and big part of smaller particles are filtered.

After this air is blown into a plenum through fans. Bottom of the plenum (ceiling of the work chamber) is built of HEPA -filters EU13 – EU14. Air streams through HEPA -filters and parallel down through the work chamber. The parallel (laminar) air flow effectively keeps the work chamber clean, free of particles. A small air volume is exhausted from the circulation through a small HEPA -filter on top of the plenum (or on side). Same air volume is taken in from ventilation system of the building or directly from the ambient.

Regulation and controls

Air velocity under HEPA -filters is 0,3 – 0,4 m/s. Light fixtures can be located between the HEPA -filters or on sides of filter area. HEPA -filters can be protected against physical damage by installing protective grilles under the filters. Side walls of the work chamber can be made of metal or plastic material. Plastic curtains or air curtain can form the front wall of the work chamber (or side wall if access to work chamber is wanted from side). Air velocity of the air curtain is 2 – 5 m/s.

Construction and materials

The effect of fans (both recirculation fans and fan of air curtain) are steplessly regulated. Switches and potentio-meters are built in the back wall of the work chamber. The first two filtering steps have their analog manometers for controlling pressure drop. Air flow under the HEPA -filters is controlled with an electronic velocity gauge which gives alarm if the flow is too low.

The module has a rigid steel profile frame which is covered with steel sheets. Side walls are made of steel or plastic material. Steel sheets can be enamelled mild steel or stainless steel AISI 304.