VERDER Carbolite Gero EHC 12/450B Manual

Installation, Operation and Maintenance Instructions
1200°C Tube Furnace (3-zone) EHC Model: 450mm
No Controller
EHC 12/450B + No Controller
MEN-EHC12450B-16_NOCTRL (09-07-2019)

Contents
This manual is for guidance on the use of the Carbolite Gero product specified on the
front cover. This manual should be read thoroughly before unpacking and using the
furnace or oven. The model details and serial number are shown on the back of this
manual. Use the product for the purpose for which it is intended.
1.0 Symbols and Warnings 4
1.1 Switches and Lights 4
1.2 General Warnings 4
1.3 Warning Labels 5
2.0 Installation 7
2.1 Unpacking and Handling 7
2.2 Siting 7
2.3 Setting Up 8
2.4 Electrical Connections 14
3.0 Temperature Controller 15
4.0 Operation 16
4.1 Operating Cycle 16
4.2 Control Method 16
4.3 Safe Operation of the Furnace 16
4.4 3-Zone Control Methods 17
A. Back-to-Back Thermocouples 17
B. Retransmission of Setpoint 18
C. Independent Control 19
4.5 General Operating Advice 19
4.6 Operator Safety 19
4.7 Tube Life 20
4.8 Pressure 20
4.9 Gas Tightness 20
5.0 Maintenance 22
5.1 General Maintenance 22
5.2 Maintenance Schedule 22
5.2.1 Cleaning 24
5.3 Calibration 24
5.4 After-Sales Service 24
5.5 Recommended Spare Parts and Spare Parts Kit 24
6.0 Repairs and Replacements 25
6.1 Safety Warning - Disconnection from Power Supply 25
2

6.2 Safety Warning - Refractory Fibre Insulation 25
6.3 Temperature Controller Replacement 25
6.4 Solid-state Relay Replacement 26
6.5 Thermocouple Replacement 26
6.6 Element Replacement 26
6.7 Fuse Replacement 27
7.0 Fault Analysis 28
A. Furnace Does Not Heat Up 28
B. Product Overheats 29
8.0 Wiring Diagrams 30
8.1 WC-13-30 30
8.2 WC-13-31 30
9.0 Fuses and Power Settings 31
9.1 Fuses 31
9.2 Power Settings 32
10.0 Specifications 33
10.1 Environment 33
Furnace drying out process 34
3

1.0 Symbols and Warnings
1.0 Symbols and Warnings
1.1 Switches and Lights
Instrument switch: when the instrument switch is operated the
temperature control circuit is energised.
Heat light: the adjacent light glows or flashes to indicate that power
is being supplied to the elements.
Heat switch: the switch disconnects power to the heating elements;
unless this switch is OFF there is a danger of electric shock when
inserting objects into the product.
1.2 General Warnings
DANGER – Electric shock. Read any warning printed next to this
symbol.
WARNING: Risk of fatal injury.
DANGER – Hot surface. Read any warning printed next to this
symbol.
WARNING: All surfaces of a product may be hot.
DANGER – Read any warning printed next to this symbol.
4

Caution – Double Pole/Neutral Fusing
1.3 Warning Labels
On the front control panel there are 2 warning labels as shown in figure 1.3.1; they are
numbered 7 and 8. These warnings must be followed for the safe operation of this
furnace.
7- Warning label - Do not operate without a work tube.
The furnace must not be operated without the correctly sized work tube
and correspond work tube adaptors or it could be possible for an
operator to access electrically live element coils that could cause serious
injury or death.
8- Warning label - Switch off the furnace before loading and
unloading.
The furnace heaters must be switched OFF using the heater switch, item
2 in figure 1.3.1, when the furnace is being loaded or unloaded. The
work tube can become electrically conductive at high temperatures,
presenting a possible hazard to the operator. If element failure is left
undetected the element could collapse onto the work tube.
5
1.0 Symbols and Warnings

1.0 Symbols and Warnings
Figure 1.3.1 - Control Box layout and warning
labels.
Figure 1.3.2- Back of control box showing
mains lead socket
Index to numbered items in Figure 1.3.1 and 1.3.2
1. Electrical supply switch - switches electrical power ON and OFF to the furnace.
2. Heater switch - switches electrical power ON and OFF to the furnace heating ele-
ments.
3. Heater ON light - indicates that the furnace heating elements are energized.
4. Product rating label indicating the product serial number and electrical inform-
ation.
5. Access holes to front panel fixing screws.
6. Warning label - Disconnect the mains supply before removing this cover.
7. Warning label - Do not operate without a work tube.
8. Warning label - Switch OFF the furnace before loading and unloading.
9. Electrical power lead socket.
10. Back panel fixing screws.
6

2.0 Installation
If the product has been transported or stored in humid conditions it
must be dried out completely before operating the furnace. Contact
Carbolite Gero Service for instructions.
2.1 Unpacking and Handling
When unpacking or moving the product, always lift it by its base or both ends of the
main body. Never lift it by the end insulation or by a work tube. It may take 2 or 3
people to lift the furnace, depending on the size and configuration.
NOTE: This product contains Refractory Ceramic Fibre (also known as
Alumino Silicate Wool - ASW). For precautions and advice on handling
this material see section 6.2.
2.2 Siting
Place the product on a level surface in a well ventilated area.
Site away from other sources of heat and on a non-flammable surface that is resistant
to accidental spillage or hot materials.
The surface on which the equipment is mounted should be stable and not subject to
movement or vibrations.
The height of the mounting surface is important to avoid operator strain when loading
and unloading samples.
Unless otherwise stated elsewhere in this manual, ensure that there is at least 150
mm of free space around the back and sides of the product. Clear space is required
above the product to dissipate heat.
Work tubes:
It is recommended that the work tube has either insulation plugs or
radiation shields fitted to minimise heat loss from both ends of the work
tube. If the work tube has open ends, a significant amount of energy
could be radiated from the ends of the work tube. Adjacent surfaces
should always be made from a non-flammable material.
Ensure that the ends of the work tube are positioned at least 500 mm
away from any adjacent surface so that any energy radiated cannot heat
an adjacent surface to a dangerous temperature.
7
2.0 Installation

2.0 Installation
If the product is to be used in a process which could liberate hazardous gases, then it
should be installed together with a suitable fume extraction system.
Ensure that the product is placed in such a way that it can be quickly switched off or
disconnected from the electrical supply.
2.3 Setting Up
The horizontal models must have work tubes fitted before being used. The diameter of
the work tube is a customer order option and therefore varies between tube furnaces.
Note: If a metal work tube is being used in the furnace, ensure that it is
earthed. See 4.6.
Under no circumstances should any objects be placed on top of the product.
Always ensure that any vents on the top of the product are clear of any
obstruction. Always ensure all cooling vents and cooling fans (if fitted) are
clear of any obstruction.
Fitting the standard length work tube to furnace
Tools required: 4 mm Allen key
Fitting work tube is as follows with reference to Figure 2.3.2. Please note that standard
length work tubes are also referred to as tubes suitable for working in air. They are 150
8

mm longer than the heated length of the furnace (see the Specifications table at the
back of this manual). Read section 6.2 before fitting the work tube.
Figure 2.3.1 - Furnace model mounted on a
control box
Figure 2.3.2 - Exploded view showing how to fit
the work tube in the furnace
Index to numbered items in Figure 2.3.2
1. Tube furnace body
2. Work tube (diameter customer option)
3. Work tube adaptor (size dependent on work tube diameter)
4. Work tube adaptor fixing bracket
5. Work tube end stop (size dependent on work tube diameter)
6. Fixing screws M6 x 15
7. Washer M6
8. Tube furnace end guard
lRemove the work tube end guard (8) then remove the work tube adaptor fixing
bracket (4) that holds in place the work tube end stop (5) and the end adaptor (3)
from one side only. Note that if a different work tube with a different outer diameter
is being fitted it will be necessary to fit new correctly sized work tube adaptors (3) in
which case both end guards and work tube adaptor fixing brackets (4) will need
removing.
lSlide the work tube into the furnace through the work tube adaptor (3) until it
reaches the opposite work tube end stop (5). Note that the work might be a tight fit
when it is new and may need to be twisted backwards and forwards slightly as it
slides in. For long work tubes it may be necessary to use a long wooden pole to sup-
port and line up the work tube as it pushed through. It may also take 2 people to per-
form this operation.
lReassemble the work tube end stop (5), work tube adaptor bracket (4) and tube end
guard (8).
Fitting the extended work tube in the furnace
Tools required 4 mm Allen key.
Fitting of the work tube is as follows with reference to Figure 2.3.2 to 2.3.8.
9
2.0 Installation

2.0 Installation
lBefore the extended work tube can be fitted, the work tube end stops for the stand-
ard length work tube (item 5 in figure 2.3.2 ) must be removed from both ends of
the furnace. This is done by removing the furnace end guard (8) and the work tube
adaptor brackets (4) to release the work tube end stop (5). The brackets should then
be refitted.
lFit the tube support bracket, (5), figure 2.3.4. Use the M6 button head screws and
washers supplied.
lFit the extended work tube guard, (4), figure 2.3.5. Use the M6 button head screws
and washers supplied.
lRe-fit furnace end guard, (3), figure 2.3.6. Use the M6 button head screws and wash-
ers supplied.
lIf supplied, fit the optional tube end seal assembly as shown in figures 2.3.9. and
2.3.10. Refer to manual MEN-ENDSEALS-01 for detailed fitting instructions.
lFit the tube support bracket, (1), figure 2.3.7. Use the M6 button head screws and
washers supplied.
lFinally, fit tube support collar, (2) and secure figure tight using (6) until the tube is
secure to be used in a vertical arrangement. The fitting arrangement is shown in fig-
ure 2.3.8.
lFigure 2.3.3 - shows an exploded view of all the required parts.
lFigure 2.3.8 - shows the assembled parts as they would be used.
Figure 2.3.3
10

Figure 2.3.4 Figure 2.3.5 Figure 2.3.6
Figure 2.3.7 Figure 2.3.8
11
2.0 Installation

2.0 Installation
Figure 2.3.9 - Tube support and end seal assembly
Figure 2.3.10 - Tube support and end seal assembly
Index to numbered items in figure 2.3.3 - 2.3.10
1. Tube support bracket
2. Tube support collar
12

3. End guards
4. Extended work tube guard
5. End adaptor
6. Fluted grip knob
Fitting the Optional Insulation Plugs and Radiation Shield
For optimum temperature uniformity, insulation plugs or radiation shields should be
placed in the work tube ends as shown below. With a standard work tube, the insulation
plug must be fitted as shown in figure A.
If a gas/vacuum end seal is fitted, either horizontally or vertically, the insulation plug
hooks onto the end seal hook; see figure B.
Alignment of radiation shields is similar to that of insulation plugs, see figure C.
If a metal work tube is being used in the furnace, ensure that it is earthed. See the
safety warning in section 4.6.
Figure A- Cross-section view showing standard
length work tube insulation plug fitted
Figure B- Cross-section view showing extended
work tube insulation plug fitted
Figure C- Cross-section view showing an extended length work tube with a radiation shield fitted
13
2.0 Installation

2.0 Installation
2.4 Electrical Connections
Connection by a qualified electrician is recommended.
All furnaces in the range are single-phase and operate over the voltage ranges 100 to
110 volts or 200 - 240 volts. Check the rating label before connection, see "Warning
Labels" for location of rating label. To check that the OP.Hi setting is correct for the
appropriate voltage, or to change to another setting, follow the instructions in section
9.2.
The electrical supply should be fused at the next standard size equal to or higher than
the design current. Where a supply cable is supplied there are internal supply fuses, in
which case customer fusing is preferred but not essential. See section 9.0 for furnace
rating power, current and fusing information.
The external connection should be either a permanent connection to a fused isolator
supply or to a socket on a fused isolator supply; the isolating switch must operate on
both conductors. Make sure that the isolator switch is within easy reach of the furnace
operator.
Supply Terminal
Label
UK/ Europe
Cable Colour
USA/
Canada
Common
Cable
Colours
Supply Type
Live -
Neutral
Reversible or
Live - Live
1-phase
L Brown Red or
Black To live to either power conductor
N Blue White To neutral to the other power
conductor
PE Green/ Yellow
Green or
Green/
Yellow
To earth
(ground) to earth (ground)
Terminal Connection Details
14

3.0 Temperature Controller
If this product is fitted with a temperature controller, instructions are provided
separately.
15
3.0 Temperature Controller

4.0 Operation
4.0 Operation
4.1 Operating Cycle
This product is fitted with an instrument switch which cuts off power to the control
circuit.
Connect the product to the electrical supply.
Turn on the instrument switch to activate the temperature controllers. The controllers
illuminate and go through a short test cycle.
Over-Temperature option only. If the digital over-temperature option has not yet
been set as required, set and activate it according to the over-temperature controller
instructions.
Switch on the heater switch, located on the instrument panel. Unless a time switch is
fitted and is switched off, the product will start to heat up. The Heat light(s) glow
steadily at first and then flash as the product approaches the desired temperature or a
program setpoint.
Over-Temperature option only. If the over-temperature circuit has tripped, an
indicator on the over-temperature controller flashes and the heating elements are
isolated. Find and correct the cause before resetting the over-temperature controller
according to the instructions supplied.
To switch off power to the heating elements, use the heater switch. To switch the
product off, use both the heater switch and the instrument switch. If the product is to be
left switched off and unattended, isolate it from the electrical supply.
4.2 Control Method
Set the three temperature controllers to the desired setpoints. The setting and
operation of the end zone controllers depends on the 3-zone control options selected
when the product was ordered. These options are described in the 3-zone control
methods section.
Note: Despite its vertical orientation, the heated zones of the KVZ model are labelled
to correspond with the relevant control module on the CC-T1 touchscreen controller
display (Left, Main, Right).
4.3 Safe Operation of the Furnace
For the safe operation of this furnace the following warnings must be followed:
16

Explosive Materials
The furnace must not be used to heat materials which could explode, or
which could emit gases that could form explosive mixtures. If the safe
heating of a material is dependent on its temperature, only heat these
type of materials if the furnace has the optional over-temperature
protection device fitted. Ensure that the over-temperature device is
calibrated and set to an over-temperature safety limit that is sufficiently
large as to avoid any hazards. If in doubt, seek expert advice before
proceeding. Customers are responsible for carrying out their own risk
assessments on the heating of materials.
Do not operate without a work tube. The furnace must not be
operated without the correctly sized work tube and correspond work
tube adaptor. Otherwise, an operator can access electrically live
element coils that could cause serious injury of death.
Switch off the furnace before loading and unloading. The furnace
elements must be switched off using the heater switch, item 2 in
"Warning Labels", when the furnace is being loaded or unloaded. The
work tube can become electrically conductive at high temperatures. If
an element has failed and collapsed onto the work tube, the work tube
will become live causing serious injury or death.
4.4 3-Zone Control Methods
There are three different control options (A, B & C).
(A) Back to back thermocouples
(B) Retransmission of Setpoint
(C) Independent control
The models listed in this manual are designed to achieve an extended uniform
temperature zone, through use of three control zones, rather than achieving different
temperatures in each zone.
For A & B, the control zones are linked so that they all follow the centre zone controller
in a master-slave approach
Note:
lOption A is NOT applicable when using the CC-T1 controller
lOption B is NOT applicable when using the Eurotherm 2132 End Zone Controller
A. Back-to-Back Thermocouples
This is the most commonly supplied option. The centre zone of the tube furnace is
controlled directly by the centre zone temperature controller. The two end zone
17
4.0 Operation

4.0 Operation
thermocouples are wired in opposition to the centre zone reference thermocouple. If
the temperatures of the centre and end zones are the same then 0°C will be displayed
on the end zone controllers. If the end zone temperatures are either higher or lower
than the centre zone, the end zone controller will display the difference in temperature
(higher = positive value, lower = negative value).
It is best practice to set the setpoint of the two end zone controllers to zero.
Alternatively, a small temperature difference (offset) can be created by setting a non-
zero value, for example to compensate for heat losses at the end or where using a gas
flow. However, the sum of the centre zone controller setpoint and the end zone
controller offset MUST NOT exceed the furnace maximum temperature.
To alter the setpoint with the display showing the Home screen, press Down
or Up once to display the setpoint and then press again or hold down to
adjust it. The display returns to the measured temperature when no key is
pressed for a short period of time.
Sometimes a furnace using this type of control does not cool down because the end
zones lose heat first and therefore the end zone controllers try to compensate for this
by switching on the end zone elements, preventing the furnace from cooling.
B. Retransmission of Setpoint
Three independent thermocouples are connected to three controllers. The three
controllers are linked together and the centre zone controller communicates the desired
setpoint to the end zone controllers. If the centre zone controller is set to a setpoint or is
running a program, the end zone controllers will automatically follow.
For products with the CC-T1 controller, please refer to the separate CC-T1 controller
manual for details on enabling and disabling setpoint retransmission.
For other products, additional communication modules are fitted in the controllers. The
communication between the controllers of the Eurotherm 3000 series is known as
Broadcast communications. It is possible to switch off the linked control and allow the
controllers to work independently. In the level 2 menu of the end zone controllers (see
controller operating instruction), scroll to L-r. Where the end zone controller is a 3216
use the up down buttons and select NO. Where the end zone controller is a 3508
use the up down buttons to select SP1, (SP1 = Local, and SP2 = Remote). There
is no need to alter the centre zone controller.
It is possible to set an offset (local trim) between the centre and end zone controllers.
This can be either a positive or negative difference from the centre zone temperature.
Once entered, this offset will always be added to, or subtracted from, the retransmitted
setpoint temperature.
For products with the CC-T1 controller, please refer to the separate CC-T1 controller
manual for details on how to set an offset trim.
18

To make this adjustment on other controllers, enter thelevel 2 menu of the end zone
controllers (see controller operating instruction), scroll to LOC.T (local trim) and use the
up down buttons to enter the desired positive or negative value. This will then be
added to, or subtract from, the end zone set temperature. There is no need to alter the
centre zone controller.
C. Independent Control
The three controllers are completely independent. Note that it is not possible to
maintain very different temperatures in the three zones because of heat transfer
between the zones. The models listed in this manual are designed to achieve an
extended uniform temperature zone by the use of three control zones rather than
achieving different temperatures in each zone.
4.5 General Operating Advice
Heating element life is shortened by overheating. Do not leave the
product at high temperature when it is not required. The maximum
temperature is shown on the product rating label and in section 10.0
towards the back of this manual.
Lightweight ceramic fibre insulation can easily be marked by accidental
contact. Some fine cracks may develop in the surface of the insulation
due to the progressive shrinkage of the insulation materials. Cracks are
not usually detrimental to the functioning or the safety of the product.
Clean up any spillages in the insulation, as these can increase the rate of degradation of
the insulation material.
4.6 Operator Safety
The ceramic materials used in the product manufacture become
electrically conductive to some extent at high temperatures. DO NOT
use any conductive tools within the product without isolating it. If a
metal work tube is used, it must be earthed (grounded).
Switch off the heater switch whenever loading or unloading the product.
The elements are isolated when the heater switch is OFF. This switch
cuts both sides of the circuit via a contactor.
19
4.0 Operation

4.0 Operation
4.7 Tube Life
A ceramic work tube may crack if work pieces are inserted too quickly or at
temperatures below 900 °C (when the tube is more brittle). Large work pieces
should also be heated slowly to ensure that large temperature differences do not
arise.
Poor thermal contact should be encouraged between the work piece and the tube;
crucibles or boats should be of low thermal mass and should have feet to reduce the
contact with the tube (fig. 4).
Key
A Tube
B Crucible
Fig 4 - Avoidance of thermal contact
Do not set too high a heating or cooling rate. As tubes are susceptible to thermal shock
and may break. Tubes which extend beyond the heated part of the furnace are more at
risk. A general rule for maximum heating or cooling rate is 400 ÷ internal diameter in
mm to give (°C/ min); for 75 mm i/ d tubes this comes to 5 °C per minute. The
controller can be set to limit both the heating and cooling rate.
4.8 Pressure
Work tubes are not able to accept high internal pressure. When gas seals or similar
fittings are in use, the gas pressure should be restricted to a maximum of 0.2 bar (3
psi). A pressure of approximately half of that should normally be sufficient to achieve
the desired flow rate. The operator must ensure that the exhaust path from the tube is
not blocked, so that excess pressure does not occur.
A suitably regulated gas supply should always be used.
It is recommended that a pressure relief system should be used to avoid an over
pressurisation of the work tube.
Please note: A product should not be heated up if any valves that have been fitted are
closed to create a sealed volume. A sealed work tube should not be heated from cold
due to the pressure increase caused by the trapped air or gas expanding during the
heating process.
4.9 Gas Tightness
Work tubes of IAP material are impervious. Sillimanite may look similar but is porous.
Ensure that the correct tube material is in use before connecting and using gases other
20