W:\ELECTRICAL\INSTRUCT\FURNACE\FURNACE GENERAL INSTRUCTIONS 2011.DOC
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01/2014
5 PROCESSING
5-1
DO NOT LEAVE THIS EQUIPMENT IN OPERATION UNATTENDED
When using any heat processing equipment there is always the risk of overheating
due to a component malfunction. A trained operator should always be present. If
this is not possible, the furnace should be located where overheating will not cause
damage to the building, adjacent stock or endanger personnel. Special consideration
should be made for the potential of smoke damage should a fire ensue. Fire
suppression equipment should be installed to protect the furnace and building. The
excess temperature limit interlock should be connected to the building alarm system.
5-2
For start-up, emergency shut down and operation of optional equipment, refer to the
specific Operating Instructions for your equipment located elsewhere in the manual.
A second set of these specific Operating Instructions are provided for posting at the
furnace for the operator.
5-3
When loading a furnace care must be taken to avoid touching or insulating the
thermocouple or temperature sensor. Free air movement around this sensor is
essential for safe and correct temperature control.
5-4
The excess temperature limit interlock should be set slightly above the operating
temperature to protect the workload. Overheating of material is a major cause of fire
loss. Excess temperature limit interlock should indicate in the same temperature
units (°F or °C) as the main controller.
5-5
An alarm should be installed that will sound upon the excess temperature limit interlock
being activated. This alarm should be installed in an area where it will attract the
attention of plant personnel properly trained to take corrective action. The wiring
schematic provided in this manual indicates where the alarm relay should be located
for this alarm circuit.
5-6
Furnaces handling flammable solvents and fuel fired furnaces have a minimum safe
exhaust rate. These furnaces have cut off dampers on fresh air and exhaust. Do not
close the fresh air or exhaust beyond these settings.
5-7
Furnaces that are designed for flammable solvent processing and/or are fuel fired,
include a purge timer. This timer is factory set based upon a specific application. DO
NOT change the purge timer setting. Purge time is calculated to exhaust four (4)
furnace volumes of fresh air prior to allowing the heat to be turned on. Reducing
purge time could result in failure to remove combustible vapors from furnace before
heat is turned on. This could result in an explosion and fire. A caution nameplate is
located next to the purge timer indicating the correct setting.
5-8
Do not overload the furnace. Air circulation and shadowing by other parts is very
important to the proper operation of a furnace.
5-8.1
Leave space between articles on each shelf (if so equipped) to allow air to move
between parts and prevent parts from shadowing each other.
5-8.2
Parts should be uniformly distributed on the furnace hearth to prevent hot or cold
spots.
