Cole Parmer Techne IFB-201, Инструкция по эксплуатации

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4) The fume extraction system (if used) should be regularly maintained. The cyclone trap collection bin
should be emptied at the end of each days use; the collected fluidising medium being returned to
the fluidised bath. It is important to ensure that the air tight seal between the cyclone and collector
bin is remade.
For maintenance of other fume treatment equipment see the associated maintenance manuals.
5) Any media trapped in the extraction hood should be cleared to ensure that all fumes are removed
from the working area through the extraction system.
The top cover/hood can be removed and any media should be returned to the bath.
SPECIAL MAINTENANCE PROCEDURES TO BE ADOPTED WHEN BURNING OFF PVC OR OTHER
HALOGENATED POLYMERS
Burning off PVC (poly vinyl chloride) in a fluidised bath offers one of the most severe conditions of
operation. Hydrogen chloride (HCL), liberated on the breakdown of PVC, is absorbed by the bed
medium, creating an acidic environment within the bed, especially when the bed also absorbs water
from the atmosphere or fluidising air when cold. HCL is extremely corrosive, especially when aerated
and wet. In addition, in water it produces water ions which, even in neutral or alkaline solutions,
promote corrosion and rusting in steel; witness for example, the corrosive nature of sea water and
calcium chloride road de-icer.
Consequently, fluidised beds used for burning off PVC require strict supervision to minimise
corrosion of the bed its self and of the parts cleaned in it, especially if these are of uncoated steel.
The purpose of most of the recommended maintenance procedure is aimed at keeping the bed
medium clean and free flowing, and free of gums, acids, agglomerates, partly decomposed plastic,
char and larger particles. These cleaning processes have the additional benefit of ensuring good
fluidisation and this, in turn reduces burn off time, reduces uneven heating of parts and thus
distortion, increases heater life by eliminating localised hot-spots, and makes cleaning easier on a
regular basis.
The following instructions apply generally to halogenated polymers and specifically to PVC. They are
aimed at minimising corrosion of the bath and of immersed metals.
a) DaIly IntervalS - at the end of each working day
1) Maintain the working temperature (about 400°C) for half an hour after the last processed
batch, to assist removal of corrosive acids from the bath.
2) If possible, maintain the temperature of the bath at about 100°C overnight and over
weekends and holidays to reduce absorption of water vapour into the batch. Overnight, the
residual heat in the bath will usually ensure this.
3) Scoop charred plastic residues, clods of media and articles being processed.
B) WeeKly IntervalS - at the end of each working week and before prolonged shut-downs
1) Ensure compliance with instruction A, above.
2) Add about 50g (2oz) of powdered mild alkali to the bath and mix in well by maintaining
fluidisation for 5 minutes. Suitable alkalis are limestone, dolomite, hydrated or slaked lime,
sodium bicarbonate, sodium carbonate, magnesia. The addition of corrosive alkalis such as
caustic soda (sodium hydroxide) and quick lime (calcium oxide) should be avoided.
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