VERDER CARBOLITE GERO RHF 14/15 Manual

Installation, Operation and Maintenance Instructions
1400 °C Rapid Heating Furnace - RHF Model: 15 Litres
No Controller
RHF 14/15 + No Controller
MEN-RHF1415-005_NOCTRL (29-10-2021)

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 Prerequisites to Use 5
2.0 Installation 6
2.1 Unpacking and Handling 6
2.2 Siting and Setting Up 6
2.3 Chimney 7
2.4 Heating Elements 8
2.5 Electrical Connections 8
Technical Notes 9
3.0 Temperature Controller 10
4.0 Operation 11
4.1 Operating Cycle 11
4.2 General Operating Notes 11
4.3 Use of Probes and Metal Sheathed Thermocouples 12
4.4 Atmospheres 12
4.5 Heating Elements 12
4.6 SiliconCarbide Protection Tiles Option 12
4.7 Operator Safety 13
5.0 Maintenance 14
5.1 General Maintenance 14
5.2 Maintenance Schedule 14
5.2.1 Cleaning 16
5.3 Safety Switch 16
5.4 Calibration 16
5.5 After-Sales Service 17
5.6 Recommended Spare Parts and Spare Parts Kit 17
5.7 Element Ageing 17
5.8 Power Adjustment 18
6.0 Repairs and Replacements 19
6.1 Safety Warning - Disconnection from Power Supply 19
2

6.2 Safety Warning - Refractory Fibre Insulation 19
6.3 Temperature Controller Replacement 19
6.4 Solid-State Relay Replacement 20
6.5 Fuse Replacement 20
6.6 Thermocouple Replacement 20
6.7 Element Fitting and Replacement 21
7.0 Fault Analysis 25
A. Furnace Does Not Heat Up 25
B. Product Overheats 26
8.0 Wiring Diagrams 27
8.1 WA-13-30 27
8.2 WA-33-30 28
8.3 WA-33-31 29
8.4 WA-43-30 30
8.5 WA-43-31 31
9.0 Fuses and Power Settings 32
9.1 Fuses 32
9.2 Power Settings 32
User Power Setting Adjustments 33
10.0 Specifications 34
10.1 Environment 34
3

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.
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.
Caution – Double Pole/Neutral Fusing
4

1.3 Prerequisites to Use
Prior to the commissioning and use of this product, all personnel involved in its
installation, operation and maintenance must be deemed competent and have:
lRead and understood the information contained within this manual
lReceived the relevant training with regard to safety and operation of the product
lBeen provided with the appropriate PPE (Personal Protective Equipment) required
for the safe operation of this product
Note: The customer is responsible for ensuring that all of the above conditions are
satisfied before the product is commissioned for use.
Note: Unless otherwise specified, the customer is responsible for the
installation of this product and the safe connection of any additional
equipment and gas or liquid supply lines.
5

2.0 Installation
2.1 Unpacking and Handling
When unpacking and handling the product, always lift it by its base. Do not use the
door or any other projecting cover or component to support the equipment when
moving it. Use two or more people to carry the product where possible.
Carefully remove any packing material from inside and around the product before use.
Avoid damaging the surrounding insulation when removing packing materials.
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 and Setting Up
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.
6

Depending on the application of the product, it may be appropriate to position it under
an extraction hood. Ensure the extraction hood is switched on during use.
Ensure that the product is placed in such a way that it can be quickly switched off or
disconnected from the electrical supply.
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.
2.3 Chimney
The chimney is a length of tubing. If it is supplied unfitted, then fit it through the hole
in the top of the case.
If the product is to be used to heat substances that emit fumes, a fume extraction duct
of approximately 75 mm - 150 mm inlet diameter may be placed directly above the
chimney outlet.
Do not make a sealed connection to the product chimney as this causes excessive
airflow through the chamber and results in poor temperature uniformity.
7

Key
A Duct (75mm-150mm diameter)
B Ambient air is drawn into duct
C Chimney
D 25mm vertical gap between chimney and duct
2.4 Heating Elements
The silicon carbide elements are VERY FRAGILE and are packed separately. Fit them
accordingly to the instructions in section 6.0 for element fitting and replacement
instructions.
2.5 Electrical Connections
Connection by a qualified electrician is recommended.
The product covered by this manual normally requires a single phase A.C. supply,
which may be Live to Neutral non-reversible, Live to Neutral reversible or Live to Live.
Some models may be ordered for 3-phase use, which may be with or without neutral.
Check the product rating label before connection. The supply voltage should agree with
the voltage on the label and the supply capacity should be sufficient for the current on
the label.
The supply should be fused at the next size equal to, or higher than the current on the
label. This manual contains a table of the most common fuse ratings.
When the mains cable is factory fitted, internal fuses are also fitted. It is essential that
the operator ensures that the product is correctly fused.
Products with a factory fitted supply cable are designed to be wired directly to an
isolator or fitted with a line plug.
Products without a factory fitted supply cable require a permanent connection to a
fused and isolated supply. The product's electrical access panel should be temporarily
removed, and connections made to the internal terminals.
8

When connecting the product to the power supply, the plug or isolating switch should
be accessible, easy to remove, and within reach of the operator.
The supply MUST incorporate an earth (ground).
Supply Terminal Label Cable Colour
Supply Types
Live - Neutral Reversible or Live-
Live
1-phase L1 Brown to live
to either power
conductor
(For USA 200-240V,
connect L1)
N / L2 Blue to neutral
to the other power
conductor
(For USA 200-240V,
connect L2)
PE Green/ Yellow to earth
(ground) to earth (ground)
Electrical Connection Details:
3-phase L1 Black to phase 1
L2 Black to phase 2
L3 Black to phase 3
N Light Blue to neutral (if fitted)
PE Green/ Yellow to earth (ground)
DO NOT connect a product ordered for three phase use to a single
phase supply or to the wrong type of three phase supply.
Technical Notes
This model has an electronically controlled power limit. Do not attempt to calculate the
Amps from the Wattage. High break capacity fuses should be used. Avoid fast-blow
fuses and magnetic trip circuit breakers - consult Carbolite Gero if in doubt.
Two-phase models use two phases out of a 3-phase + neutral supply. One phase is
unused. The neutral current is equal to the current in one of the used phases.
9

3.0 Temperature Controller
If this product is fitted with a temperature controller, instructions are provided
separately.
10

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.
The product will heat up according to the controller setpoint or program, unless a time
switch is fitted and switched off.
As the product heats up, the heat light glows steadily at first and then flashes as the
product approaches the desired temperature. For more information on temperature
control see the controller instructions.
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 turn the product off, set the instrument switch to its off position. The controller
display will go blank. If the product is to be left unattended, isolate it from the
electrical supply.
4.2 General Operating Notes
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.
When heating large objects, in particular poor conductors, avoid shielding the
thermocouple from the heating elements. The thermocouple is intended to sense the
temperature near the heating elements. However, if a large object is placed in the
chamber it may record the average temperature of the object and the elements, this
can lead to overheating of the elements. Allow large objects to gain heat at a lower
temperature and then reset the controller to a temperature close to the desired
maximum, or heat using a slowly controlled ramp rate. For more information refer to
the controller instructions.
When heating materials that produce smoke or fumes, the chimney must be correctly
fitted and unobstructed. If not, soot will accumulate in the chamber and could possibly
cause an electrical breakdown of the heating element. If the furnace is used to heat
materials that emit smoke or fumes, regularly heat it up to maximum temperature for
one hour with the chamber empty to burn away the soot.
11

Materials such as case hardening compounds and other reactive salts may penetrate
the furnace chamber lining and attack the wire elements, causing premature failure.
Use of a hearth tile may be advisable: please consult the Carbolite Gero technical
department.
4.3 Use of Probes and Metal Sheathed Thermocouples
Any metal object used to probe into the product chamber while the
product is connected to the electrical supply must be earthed. This
applies in particular to metal sheathed thermocouples, where the
sheaths must be earthed. The refractory material of the chamber
lining becomes partly conductive at high temperatures and the
electric potential inside the chamber can be at any value between
zero and the supply voltage. Unearthed probes can cause serious
electric shock.
4.4 Atmospheres
When an optional gas inlet is fitted, there is a label near the inlet saying "INERT GAS
ONLY". In practice, inert or oxidising gases may be used, but not combustible or toxic
gases.
The chamber is not gas tight, the gas usage may be high and the chamber is always
likely to contain some air. Residual oxygen of approximately 1% to 2% is to be
expected.
4.5 Heating Elements
If SiC heating elements are used close to their maximum operation temperature of
1600 °C it is possible for bubbles of silica to form on the surface of the elements. The
size of the bubbles can vary. This is an indication that the elements temperature has
exceeded 1625 °C. The silica bubble can be removed, if they are a nuisance to the
application, by careful use of a vacuum cleaner with an appropriate exhaust filter. To
reduce the likelihood of silica bubbles forming, heat the furnace using a reduced
heating rate and if possible use a lower setpoint.
4.6 SiliconCarbide Protection Tiles Option
This product is available with optional heating element protection tiles. When this
option is specified, silicon carbide (SiC) tiles are added to the insulation assembly,
positioned on both sides of the chamber to create a barrier between the working
chamber and the heating elements. This will protect the heating elements from
potentially harmful contaminants that might be placed in the chamber.
12

This option is ideal for processes which can create acids, water, fumes or aggressive
gases that can react with and damage the heating elements.
The addition of the heating element protection tiles option reduces the width of the
internal chamber and the maximum operating temperature. Please refer to the
"Specifications" section of this manual for further details.
4.7 Operator Safety
This product incorporates a safety switch which interrupts the
heating element circuit when the furnace is opened. This prevents
the operator touching a live heating element and also prevents the
product from heating up if the furnace is left open. The operation of
this switch should be checked periodically.
Depending on use, the surfaces in the working chamber and the
chamber load may still be very hot after the appliance is switched
off. Touching these surfaces may cause burns. Use suitable personal
protective equipment or wait until the appliance cools down to
ambient temperature.
Before removing a hot object from the product, make sure there is a safe place to put
it down. If necessary use tongs, face masks and heat resistant gloves. Heat resistant
clothing and face protection can guard against the effects of radiated heat when the
furnace is open.
When the product is opened during operation there is considerable radiated heat. Do
not keep any flammable objects near the product, nor objects which could be damaged
by radiated heat.
13

5.0 Maintenance
5.1 General Maintenance
Preventive rather than reactive maintenance is recommended. The type and frequency
depends on the product use; the following are recommended.
5.2 Maintenance Schedule
CUSTOMER
QUALIFIED PERSONNEL
DANGER! ELECTRIC SHOCK. Risk of fatal injury. Only electrically
qualified personnel should attempt these maintenance procedures.
Maintenance
Procedure Method
Frequency
Daily Weekly Monthly Bi-
Annually Annually
Safety
Safety Switch Function
Set a safe temperature above ambient,
and open the door to see if the heater
light goes out
Safety Switch Function Electrical measurement
Over-Temperature
Safety Circuit
(if fitted)
Set an over-temperature setpoint lower
than the displayed temperature and
check for an over-temperature alarm as
detailed in this manual
Over-Temperature
Safety Circuit
(if fitted) Electrical measurement
Door Plug Visual inspection, checking the seal and
whether it is free of damage
Door Plug Replacement where necessary
Chimney / Extraction Check and clean if necessary
Electrical Safety
(external) Visual check of external cables and plugs
Electrical Safety
(internal)
Physically check all connections and
cleaning of the power plate area
Function
Temperature Calibration
Tested using certified equipment, fre-
quency dependent on the standard
required
14

Operational Check Check that all functions are working nor-
mally
Operational Check Thorough inspection and report incor-
porating a test of all functions
Performance
Element Circuit Electrical measurement
Power Consumption Measure the current drawn on each
phase / circuit
Hearth Visual check for fit and damage
Cooling Fans (if fitted) Check whether the cooling fans are work-
ing
15

5.2.1 Cleaning
Soot deposits may form inside the furnace, depending on the process. At appropriate
intervals remove these by heating as indicated in the General Operation Notes.
The product's 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.
5.3 Safety Switch
When correctly functioning, the safety switch will isolate all live conductors (live and
neutral connections) within the heating element circuit(s) when the product door is
opened. The safety switch should be checked regularly to ensure that this occurs.
The safety switch should not fail under normal working conditions, however rough
handling, exposure to corrosive materials/ environments, or exceptionally frequent use,
could compromise the safety system.
Weekly check:
The following check can be carried out by a general operator:
lOn the temperature controller, set a safe temperature above ambient. The heater
lights should illuminate.
lOpen the door and check the heater lights. They should no longer be illuminated.
If the heater lights remain illuminated when the door is open, discontinue use and
contact Carbolite Gero Service.
Annual check:
The following checks should be carried out by a qualified electrician, as specified in the
"Maintenance Schedule" section of this manual:
lRemove the element access panel and take a voltage measurement from the heat-
ing element terminals. Do not attempt to take a reading from the heating element
itself as surface oxidation will give an unreliable contact.
lEnsure that power to the heating elements is switched off when the door is opened.
Contact Carbolite Gero Service and discontinue use of the product if it is found that the
heating elements are not fully isolated during these checks.
5.4 Calibration
After prolonged use, the controller and/or thermocouple may require recalibration. This
is important for processes that require accurate temperature readings or for those that
16

use the product 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. Carbolite Gero can supply these
items.
Depending on the controller fitted, the controller instructions may contain calibration
instructions.
5.5 After-Sales Service
Carbolite Gero Service has a team of Service Engineers who can offer repair, calibration
and preventive maintenance of furnace and oven products both at the Carbolite Gero
factory and at customers’ premises throughout the world. A telephone call or email
often enables a fault to be diagnosed and the necessary parts to be despatched.
In all correspondence please quote the serial number and model type given on the
rating label of the product. The serial number and model type are also given on the
back of this manual when supplied with the product.
Carbolite Gero Service and Carbolite Gero contact information can be found on the
back page of this manual.
5.6 Recommended Spare Parts and Spare Parts Kit
Carbolite Gero can supply individual spare parts 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 consists of one thermocouple, one sheath, one solid-state relay, one door
insulation piece, a set of elements, a set of element clips and a set of braids and clips.
Individual spare parts are also available.
When ordering spare parts please quote the model details as requested above.
5.7 Element Ageing
Silicon carbide elements gradually increase in resistance with use; a process known as
ageing. Their heating power reduces correspondingly. To ensure sufficient power to the
product, it may be necessary to adjust the power limit and, ultimately, replace the
elements - taking care to readjust the power limit.
Note: A clamp meter should be used when adjusting the power limit to ensure that
the current is not inadvertently increased beyond safe limits. Please contact
Carbolite Gero Service for guidance on safe current limits.
If the product does not reach temperature, or is slow, check the power limit setting and
increase the value by 5%. It is recommended to make a note of the new settings and
the date of the adjustment in section 9.0. Increase the power limit in steps of 5% until
the product regains its original performance.
If the power limit is set to 100% a new set of heating elements is required.
17

Please note: it is not possible to use the cold resistance of the element as a measure
of ageing as the cold resistance is not an accurate indicator of hot resistance. Hot
resistance is used to calculate furnace power.
See the controller instructions for how to adjust the controller. Always record the
setting when first making an adjustment. If new elements are fitted, return the
adjustments to the original value. A table of standard power limits is given in section
9.0.
5.8 Power Adjustment
The product's control system incorporates electronic power limiting. Power is supplied
to the elements in bursts of approximately 0.33 seconds duration. This prevents
overheating of the elements. The power limit is programmed into the product
controller.
A table of standard power limits is supplied with new products, it is given in section 9.0
18

6.0 Repairs and Replacements
6.1 Safety Warning - Disconnection from Power Supply
Immediately switch the product off in the event of unforeseen
circumstances (e.g. large amount of smoke). Allow the product to
return to room temperature before inspection.
Always ensure that the product is disconnected from the electrical
supply before repair work is carried out.
Caution: Double pole/neutral fusing may be used in this product.
6.2 Safety Warning - Refractory Fibre Insulation
Insulation made from High Temperature Insulation Wool
Refractory Ceramic Fibre, better known as (Alumina silicate
wool - ASW).
This product contains alumino silicate wool products in its thermal insulation. These
materials may be in the form of blanket or felt, formed board or shapes, slab or loose
fill wool.
Typical use does not result in any significant level of airborne dust from these
materials, but much higher levels may be encountered during maintenance or repair.
Whilst there is no evidence of any long term health hazards, it is strongly
recommended that safety precautions are taken whenever the materials are handled.
Exposure to fibre dust may cause respiratory disease.
When handling the material, always use approved respiratory protection
equipment (RPE-eg. FFP3), eye protection, gloves and long sleeved clothing.
Avoid breaking up waste material. Dispose of waste in sealed containers.
After handling, rinse exposed skin with water before washing gently with
soap (not detergent). Wash work clothing separately.
Before commencing any major repairs it is recommended to make reference to the
European Association representing the High Temperature Insulation Wool industry
(www.ecfia.eu).
Further information can be provided on request. Alternatively, Carbolite Gero Service
can quote for any repairs to be carried out either on site or at the Carbolite Gero
factory.
6.3 Temperature Controller Replacement
Refer to the controller instructions for more information on how to replace the
temperature controller.
19

6.4 Solid-State Relay Replacement
Disconnect the product from the power supply and remove the
appropriate cover as given above.
1. Make a note of the wire connections to the solid state relay, then disconnect them.
2. Remove the solid state relay from the base panel or aluminium plate.
3. Replace and reconnect the solid state relay ensuring that the bottom of it has good
thermal contact with the base panel or aluminium plate.
4. Replace the access panel.
6.5 Fuse Replacement
Fuses are marked on the wiring diagram with type codes, e.g. F1, F2. For more
information on fuses refer to section 9.0.
Depending on model and voltage, the different fuse types may or may not be fitted.
If any fuse has failed, it is advisable for an electrician to check the internal circuits.
Replace any failed fuses with the correct type. For safety reasons do not fit larger
capacity fuses without first consulting Carbolite Gero.
The fuses are located at the cable entry point. Remove the back panel or control box
back panel to gain access to the fuses.
6.6 Thermocouple Replacement
Disconnect the product from the power supply. Remove the appropriate
panel to gain access to the thermocouple connections. Make a note of the
thermocouple connections.
Thermocouple cable colour codings are:
Thermocouple leg Colour
positive (type R) orange
negative white
Disconnect the thermocouple from its terminal block and withdraw the thermocouple
from its sheath by bending the metal tag or releasing the screw to release. It is also
advisable to remove the sheath and shake out any broken pieces of thermocouple.
Re-assemble with a new thermocouple, observing the colour coding, ensuring that the
thermocouple is not twisted as it is being inserted and that the metal tag is bent back
to grip the sheath.
Refit the element access panel.
20