Carbolite VST Series - Manual (Page 7)

HST, VST
MF13 – 3.40
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
Check the furnace interior. If soot deposits have formed, remove by heating up to maximum
temperature for one hour without load.
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 safety switch operation mentioned in 3.3 should be checked periodically to ensure that heating
elements are isolated when the furnace 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 furnace 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 covers: probing the element surface inside the furnace could be inconclusive because of surface
oxidation. Note that all live supply wires of a 3-phase supply, and both live and neutral of a 1-
phase supply, 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. These items can be supplied by Carbolite.
Depending on the controller, the controller manual may contain calibration instructions.
4.3 After Sales Service
Carbolite’s service division (Carbolite 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 Carbolite. 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 Carbolite Engineering Services or Carbolite see the back page of this manual.
4.4 Recommended Spares Kits
Carbolite 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. Each kit comprises one thermocouple,
one solid state relay, and two heating elements (models /900: 2 of each length).
When ordering spares please quote the model details as requested above.