Fault Finding - Techne IFB-101 Operator's Manual

FAULT FINDING

Any service or repair work should only be carried out by a trained electronic or
electro mechanical technicians. Untrained personnel should not attempt to dismantle this
equipment.
a) If the cut-out indicator fails to extinguish when the reset switch is depressed, check the
temperature of the fluidised bath to determine whether the bath has overheated and operated
the temperature cut-out. Check the setting of the over temperature cut-out which is situated
within the electrical control console. The over temperature cut-out is factory set to a
maximum temperature of 630°C. The cut-out can be re-set by depressing the red knob on
the bottom of the cut-out.
To over-ride the door safety switch pull the knob down slightly and out.
Also check that compressed air is being supplied to the fluidised bath and that the air
pressure switch is being held in the on position. When operating correctly the air pressure
regulator situated within the pneumatic control console should be set at 204k Pa (30psi) and
the bath should be fluidised.
b) If the fluidised bath fails to reach its operating temperature or the heat-up rate decreases,
check the level of fluidisation. Where an air flowmeter is fitted, check that the air flow rate
agrees with the recommended values, and in any case check that the fluidised bed is evenly
fluidised with bubbles of approximately 50mm diameter.
Also check that the heater elements are functioning correctly. Three heater elements are
fitted which produce a total heater power of 6kW. The heater elements are individually
terminated within the control console (see attached circuit diagrams for wiring details).
To inspect the heater elements, remove the inner container from the outer wrapper, then
remove the three layers of thermal insulation that surround the fluidised bath. The heater
elements are of the ceramic knuckle type, each element being clamped to the inner
container. To remove an element, disconnect the two lead wires from the terminal strip and
unbolt the heater clamps.
Before fitting a new heater element, inspect the walls of the inner container to ensure the
walls are not deformed. It is vital that the heater element is in close contact with the walls of
the container. Any surface irregularities should be treated before a new element is fitted.
Reassemble the unit in reverse order, ensuring that the new heater element is bolted tightly
to the inner container.
c) If the fluidisation within the bath deteriorates, check the compressed air supply and the air
filter assembly. Replace the air filter elements if necessary. Where a flowmeter is fitted,
check the air flow rates correspond with the recommended values. If an automatic fluidising
air control system is fitted and the air flow rates do not agree with the values, re-adjust the
system in accordance with the following:-
i) Ensure that the air pressure regulator is set at 204kPa (30 psi).
ii) FOR UNITS UP TO ISSUE/5 (with two contactor system).
Adjust the set point of the automatic air control temperature monitor which is located
within the electrical console so that both of the air control solenoid valves are closed. The
automatic air control temperature monitor is the right hand monitor.
iii) Adjust the manual valve at the bottom of the pneumatic control console adjacent to the air
filter assembly until the indicated air flow rate is approximately 70 l/min.
iv) Reset the right hand temperature monitor to a temperature of 400°C which will energise
the lower solenoid valve. Adjust the central valve until the total indicated airflow rate is
approximately 110 l/min.
I F B - 1 0 1 O P E R A T O R ' S M A N U A L
PAGE 21