The Problem
A school woodworking department in the South West of England had had a new dust extraction system installed. The three classrooms this system was designed to service run in a line along the main corridor. Once the extraction system was on for one of the classrooms it was on for all the classrooms. The system had been correctly calculated to offer a more than adequate air velocity and was serviced by a single fan and filter system.
The problem the school was experiencing was that once the system was on to extract dust for one class it was on for all woodworking machines in all the classrooms. This was causing a noise issue for the other classrooms whilst teachers were trying to teach and communicate with the pupils.
The Solution
The school decided to retrofit a control system which activated the extraction only where and when individual machines were being used. Other inactive positions would be turned off by automatic dampers controlled by the central control unit. The fan speed was also controlled by the central PLC via an inverter.
Each automated damper point was activated by a 24v switch, either a current sensor, a manual rocker switch or by being hardwired directly into the machine. The PLC controller was programmed to ensure that even if only a couple of machines were being used enough other dampers were opened to maintain minimum air velocity.
The Results
The results have been threefold for the school,
- The noise issues they were having were reduced substantially
- They did not have to redesign or reinstall their system to achieve their goal
- By not using the system at full capacity all the time they are saving on their energy costs and the return on investment of the control system is within 18 months and expected life of the equipment has been extended
The Lessons
Although an extraction system must be designed to be able to cope with maximum usage, it is very rare that every extraction point is needed at the same time.
It is possible to control this and save energy and the environmental impact of the installation.
Research the market for a control system which will intelligently manage your system and most importantly still operate minimum velocities to keep the extraction within design stipulations.
The installation company are Western Air Ducts and the control system they installed is called Inteliair