For older units the following control parameters have been factory pre-set on the Eurotherm 807:-
High Alarm
Hi Al
630°C
1166°F
Low Alarm
Lo Al
0°C
32°F
Deviation Alarm
D. Al
630°C
1166°F
Proportional Band
P
17%
17%
Integral Time
I
124 sec
124 sec
Derivative Time
D
3 sec
3 sec
Heater Cycle Time
HCT
0.3 sec
0.3 sec
High Cut Back
HCB
17°C
62°F
Low Cut Back
LCB
17°C
62°F
As the fluidised bath heats up the fluidisation will become more vigorous, due to the expansion of the
fluidising air. Units fitted with the automatic fluidising air control system will automatically reduce the air
input so as to keep a constant level of fluidisation. Manually operated units must have fluidising air flow
reduced until the level of fluidisation returns to its original state. The following table indicates the flow
rates that are factory set on an auto-air unit
Ambient to 200°C
220 l/min
200°C to 400°C
180 l/min
400°C to 600°C
150 l/min
The fluidised bath should be operated with the bath lid fitted to reduce heat loss during the heat up
period, and to increase the efficiency of the fume extraction system. As the temperature of the fluidised
bath approaches the set point, the heater indicator, situated in the temperature controller fascia, will
cycle on and off, until the actual temperature reaches the set point temperature.
It may be desirable, depending on the process being carried out in the fluidised bath, to check the actual
bath temperature with an independent temperature sensor. Any offset in the temperature may be
corrected by adjustment of the temperature controller (an instruction manual for the temperature
controller is included with this manual). Further temperature checks may be made at various points
within the fluidised bath to ensure good temperature uniformity is being achieved throughout the bed.
Slight adjustment of the fluidising air flow rates will reduce any excessive temperature gradients.
CautIOn:
Care should be taken when handling hot parts which have been removed from a fluidised
bath. We recommend that protective clothing (gloves, aprons, and visors, etc) be worn at all times when
working with fluidised baths and that the installation and maintenance procedures outlined in this
booklet be followed explicate.
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