Caf Digital Imaging
MF36
page 15
4.0
O
PERATING
I
NSTRUCTIONS
.
4.1
Furnace Start-up.
This furnace is available in two options:
Option 1.
CO/CO2 ‘reducing’ gas and Air ‘oxidising’ gas with N2 ‘Purge’ gas.
Compatible with - ASTM D 1857-87.
Option 2.
H2 and CO2 ‘reducing’ gases and CO2 ‘oxidising’ gas with CO2 ‘Purge’ gas.
Compatible with - BS 1016 : Part 113 : 1995 ISO 540.
The principle of operation is the same for both options. The furnace is normally supplied
programmed to operate between a pre-determined set point (start temperature) and 1500°C
(2732°F) at a ramp rate of 7°C/min. (12.6
°
F/min.). The target temperature is set to 1500°C
(2732°F) to avoid operating the furnace at high temperatures unnecessarily. See section 4.5.1.
The following text describes how to use the furnace with this program.
4.1.1. Open the furnace door to check that the silica window is clean. Any slight haze should be
removed before use. If neglected this haze quickly thickens and becomes impossible to remove.
See section 5.4. for instructions on how to remove and clean the viewing window.
4.1.2. Turn on the ‘oxidising’, ‘reducing’ and ‘purge’ gas supplies. If the ‘purge’ gas is not present
when the furnace electrical supply and instrument switch are on the control system will activate
an alarm buzzer and illuminate a warning light on the control panel. See fig 11. This alarm will
continue until the furnace is turned off and the ‘purge’ gas supply is restored. While the alarm is
activated the control system will not allow introduction of ‘reducing’ gas.
4.1.3. Switch on the furnace electrical supply, the instrument switch will illuminate and the cooling
fans will run. Operate the instrument switch to activate the control system, the furnace will begin
to heat up to the start temperature and the work tube will be purged with ‘Purge’ gas. The start
temperature is adjustable using the Up and Down buttons (
qp
) on the controller depending on
your requirements:
For furnaces constructed to use CO/CO
2
and Air test gases with N
2
‘Purge’ gas (compatible
with ASTM D 1857-87. The start temperature is adjustable from 400°C (752 °F).
For furnaces constructed to use H
2
and CO
2
test gases with CO
2
‘Purge’ gas (compatible with BS
1016 : Part 113 : 1995 ISO 540. The start temperature is adjustable from 815
°
C (1499
°
F).
To switch the furnace off, set the instrument switch to off. The case cooling fans remain on.
Leave the fans on until the furnace cools to below 300°C. If the furnace is to be left off, isolate it
from the electrical supply.
Note:
It is not recommended to operate the furnace continuously at temperatures above 1000
°
C
(1832
°
F). The furnace is designed to operate to a programmed ramp; continuous operation at
elevated temperatures will shorten the life of the elements, insulation and tube end seals.
4.2
Eurotherm Controller.
The Eurotherm controller is configured to control the furnace and provide the other signals
necessary to switch gas flows and communicate with the CAF Test Software. The following
sections describe how to adjust the controller as necessary to achieve correct operation of your
furnace.
4.3
Computer Start-up.
The computer is set up by Carbolite to run the following software:
Microsoft Windows 2000 (earlier models: Windows 98).
Carbolite Coal Ash Fusibility Test software: protected by a hardware lock (dongle).
Although the software is already installed, installation CDs are supplied for system support.