Energy Saving Fume Cupboards
  • V.A.V. ( Variable Air Volume ) Systems

One of the most efficient methods of reducing heating costs in a laboratory where fume cupboards are in constant use,  is to install a V.A.V. control system. A V.A.V. system can be fitted as part of a new installation or retro fitted to existing fume cupboards and extract systems. The basic principal of a V.A.V. system is to reduce the amount of heated air being extracted through the open sash of a fume cupboard, this is achieved by the sash position controlling a damper on the outlet of the fume cupboard. When the sash is open at 500mm the fume cupboard damper will be set at an open position to achieve the required flow rate through the fume cupboard, the extract fan will be running at a constant speed with a constant discharge velocity at the discharge point.

The V.A.V. airflow monitor measures the air flow rate through the open sash, as the sash is closed the damper above closes in order to maintain a constant face velocity across the face of the sash, thus reducing the volume of heated air being extracted. To maintain a constant efflux velocity on the discharge stack a bleed air damper will open and allow outside air to flow through the fan and discharge stack. The bleed air damper is controlled by a pressure sensor in the extract ductwork.

Additional monitors and controls can be fitted in order to control the amount of heated air being supplied into the laboratory via the A.H.U., a room pressure monitor will constantly measure the room pressure and as the fume cupboard sashes are closed to reduce the amount of extracted heated air, the A.H.U. heated air into the laboratory is also reduced, the A.H.U. air output can be controlled either by a damper or motor inverter.

To gain maximum benefit from this type of system, the user must close the fume cupboard sash when access is not required.

  •  Automatic Sash Closer

 The A.S.C. ( Automatic Sash Closer ) solves the problem of users walking away and leaving the sash open, as discussed above this can lead to vast amounts of heated air being wasted unnecessarily. The fume cupboards are fitted with a P.I.R. sensor in order to detect movement around the fume cupboard, whilst there is movement around the fume cupboard the sash will stay in its current position. If no movement is detected within a pre determined time then the sash will close automatically, as a safety feature if any obstruction is detected within the line of the closing sash then the sash will stop.

The system does not open the sash automatically, this is carried out manually.

The sash can be operated up or down manually at any time.

If both auto sash closer and V.A.V system are fitted significant savings can be made on your energy costs.