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1.4
Maintenance Considerations for Airbath and Airless Ovens
The following practices must be observed in order to operate, maintain and prevent
compromise of the airbath oven (including programmed temperature oven) and airless ovens
of Maxum II. Modular ovens are described in the next section.
● The user must ensure that the analyzer T-rating is suitable for the area in which the analyzer
is to be installed. If a particular application requires oven temperatures that are very hot, it
may be necessary to locate the analyzer in a different area of the plant that has a better T-
rating. It is the responsibility of the user to ensure that the actual, final analyzer T-rating is
suitable for the area of installation.
● Instrument air supplied to the airbath oven of the analyzer must be clean and dry as
described above. Unsuitable air may cause smoke or other damage to the analyzer and
can result in a hazardous condition.
● The set point resistors used to control the T-rating must have the correct value for the
desired T-rating. These resistors are installed at the factory and should be changed only
by properly trained service personnel. If these resistors are the wrong value, it could be
possible for temperatures within the oven to become too hot for the stated T-rating of the
analyzer.
Note
Always replace the set point resistor board with the same part number and resistance
values. Multiple heated devices in the same analyzer with the same T rating can have
different set point resistor values based on the size of the heater and design of the heater
housing.
● For the airbath oven, the heater apparatus should be inspected for physical damage. If
there are any cracks, bends or other damage, the assembly must be switched off
immediately and replaced. All fittings and conduit attachments must be tight and installed
according to local codes.
● It is possible for heater elements to burn out. In either oven type, the new heater must be
installed using proper techniques.
– For the airbath oven, if the heater is to be replaced, the factory spare part is a complete
sealed system. It cannot be disassembled for repair in the field. If the heater element
or any attached components fail, the entire heater assembly must be replaced with a
new replacement part from the factory.
– For the airless oven, it is possible to replace only the heating element.
Oven Types
1.4 Maintenance Considerations for Airbath and Airless Ovens
Maxum II Valves and Oven Components
Service Manual, 10/2018, A5E42019844001
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