EF, AF
LF01
7
4.0 M
AINTENANCE
4.1 General Maintenance
Preventive rather than reactive maintenance is to be preferred. The type and frequency depends on
furnace use: the following are recommended.
4.1.1 Cleaning
Soot deposits may form inside the furnace, depending on the process. At appropriate intervals
remove these by heating as indicated in section 3.2.
The furnace outer surface may be cleaned with a damp cloth. Do not allow water to enter the
interior of the case or chamber. Do not clean with organic solvents.
4.1.2 Safety Switch
The door switch operation mentioned in 3.6 should be checked periodically to ensure that heating
elements are isolated when the door is opened. In normal conditions the safety arrangement should
outlast the furnace, but it could be affected by rough handling, a corrosive environment or work
materials, or exceptional frequency of use.
A qualified electrician should check that the supply to the heating elements is cut, with and
without power being on, when the door is open partially and fully; it is important that isolation is
not just marginally achieved. The check is best made on the element terminals after removal of the
furnace back: probing the element surface inside the furnace could be inconclusive because of
surface oxidation. Note that both live and neutral sides of the element should be isolated when the
door is opened.
4.2
Calibration
After prolonged use the controller and/or thermocouple could require recalibration. This would be
important for processes which require accurate temperature readings or which use the furnace
close to its maximum temperature. A quick check using an independent thermocouple and
temperature indicator should be made from time to time to determine whether full calibration is
required.
Depending on the controller, the controller manual may contain calibration instructions.
4.3
After Sales Service
Lenton’s service division (Thermal Engineering Services) has a team of Service Engineers capable
of repair, calibration and preventive maintenance of furnace and oven products at our customers’
premises throughout the world. We also sell spares by mail order. A telephone call or fax often
enables a fault to be diagnosed and the necessary spare part despatched.
Each furnace has its own record card at Lenton. In all correspondence please quote the serial
number, model type and voltage given on the rating label of the furnace. The serial number and
model type are also given on the front of this booklet when supplied with a furnace.
To contact Thermal Engineering Services or Lenton see the back page of this manual.
4.4
Recommended Spares Kits
Lenton can supply individual spares, or a kit of the items most likely to be required. Ordering a kit
in advance can save time in the event of a breakdown.
When ordering spares please quote the model details as requested above.
Summary of Contents for Lenton AF 11/6
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