mixer mechanically does pose a hazard to operators when inverting 1800 to the
mixing position and lowering to the levelling and discharge position. The in-built siren does
operate at each change of operating state to warn of machine movement but under Health
and safety regulation in a number of countries enclosure protection is required.
This enclosure will be supplied by Plas mec or the machine can be installed to customers
requirements within customer specified enclosures. Access is usually by key exchange
interlock or infra red entrance protection systems interlocked to the mixing position
The options of each type of mixer depend on customer requirements, do you need a
dedicated Bonding mixer, what size of batch of bonded powder coatings are required, do
we have a constraint on bonding mixer cycle times.
Generally the machine can be modified to Bond powder coatings as well as pre-mixing but should be viewed as a part time Bonding system. Due to its longer cooling cycle and vertical configuration it does not lend itself to 100% bonding operation.
The standard drive system would need to beupgraded for Metallic bonding in order to operate this would require the larger motor andvariable speed control with the add on equipment for dosing the metallic pigment and N2
purging the mixer unit. This specification is usually specified before manufacture and not
Dust Extraction System
The dust extraction system is required to prevent airborne emissions of powder during preweigh, loading the fixed mixer, unloading the portable container mixer and discharging to
Therefore the dust filter will need explosion relief. If the raw materials are
handled very carefully during pre-weigh and loading, then the amount of exposable dust
entering the extraction system should be very low. Nevertheless, the possibility of fines
entering the dust extraction system cannot be ruled out. On this basis, the explosion relief
should be sized to cope with an explosion class ST1 powder (i.e. Kst > 200 bar.m/s).
The dust extraction unit should be as small, located outside, and away from areas of
occupancy as possible. The relief should direct outside to a safe area.
The dust filter bags should be anti-static and earthed to the bag frame. A metal collection
bin should be used and this should be earthed to the main filter housing and emptied on a
regular basis. Emptying at the end of every shift is recommended.
The extraction ductwork should be conductive and as straight as possible and the airflow
sufficient to ensure at least 23 m/s duct velocity. The duct should have some inspection
access to permit easy checking of build up and cleaning out of dust. Ducting should have
smooth internal surfaces and any lap joints should face the direction of airflow. The
extraction fan must be located on the clean side of the filter and located outside if possible
in a soundproof enclosure.