Fisher Scientific Isotemp 550 Series User manual

Isotemp®Muffle Furnace
550 Series
Instruction Manual
Model 14
Catalog No. 10-550-14 & 14A
Model 58
Catalog No. 10-550-58
Model 126
Catalog No. 10-550-126
83854 • 04/11/06

Table of Contents
Safety Information ..............................................................................................................................................3
Alert Signals..................................................................................................................................................3
Introduction..........................................................................................................................................................4
Installation ..........................................................................................................................................................5
Selecting a Location ....................................................................................................................................5
Unpacking ....................................................................................................................................................5
Preparing the Furnace ..................................................................................................................................6
Furnace Layout ..................................................................................................................................................7
Operation ............................................................................................................................................................8
Power On Reset ..........................................................................................................................................8
Entering a Set Temperature..........................................................................................................................8
Setting the Display Offset ............................................................................................................................8
Example Offset ............................................................................................................................................9
Open Thermocouple ....................................................................................................................................9
Over-Temperature Indicator..........................................................................................................................9
Service ..............................................................................................................................................................10
Replacing a Heater ....................................................................................................................................10
Replacing the Thermocouple ......................................................................................................................11
Troubleshooting ................................................................................................................................................12
Replacement Parts............................................................................................................................................13
Accessories and Supplies ................................................................................................................................14
Performance Characteristics ............................................................................................................................15
Specifications ....................................................................................................................................................16
Wiring Diagram..................................................................................................................................................17
Warranty ............................................................................................................................................................20

3
Your Fisher Isotemp®Programmable Muffle Furnace has
been designed with function, reliability, and safety in
mind. It is your responsibility to install it in conformance
with local electrical codes. It is most important that the
user follow installation instructions exactly as written.
Failure to do so is likely to lead to improper operation,
erroneous calibrations and possible damage to the equip-
ment. Do not attempt operation without this information.
When operating the furnace, always observe the following
Safety Precautions:
• Wear insulating gloves.
• Use tongs.
• Use safety goggles.
• Never stand in front of an open furnace.
• Use the supplied hearth plate on the chamber
bottom
Safety Information
Warning
Warnings alert you to a possibility of
personal injury.
Caution
Cautions alert you to a possibility of
damage to the equipment.
Note
Notes alert you to pertinent facts and
conditions.
Hot Surface
Hot surfaces alert you to a possibility
of personal injury if you come in con-
tact with a surface during use or for a
period of time after use.
Alert Signals

4
Introduction
Fisher Isotemp 550 Series Muffle Furnaces are available
in three sizes: small (Model 14), medium (Model 58) and
large (Model 126). All models provide PID microproces-
sor temperature control at operating temperatures from
50 to 1125°C (90 to 2057°F).
Furnace chambers are molded from alumina silicate
ceramic fibers. Use of this material provides low thermal
mass for fast heat-up and cool-down, as well as an
unusually low exterior furnace temperature for safe opera-
tion. The furnace is heated by electric resistance ele-
ments embedded in easily removable side and base pan-
els. The heating elements are designed to ensure
extended service life, even in atmospheres characteristic
of high-sulfur coal and coke samples.
Temperature readout can be easily viewed on the 7-seg-
ment display. A heater LED located to the left of the tem-
perature display indicates when the heater is being ener-
gized.
For operation with chamber atmospheres other than air
(N2, C02, etc), external gas supplies connect easily
through a provided 3/8-inch port. An Injection Port Kit
(10-550P) connected to the exhaust port allows
convenient venting of the chamber.
Isotemp furnaces incorporate a variety of safety features.
When the furnace door is opened, power is automatically
cut to the chamber heating elements. The heater power is
also cut out when the chamber temperature exceeds the
set temperature by 100°C or more. The alarm condition
is indicated by a flashing “HIGH” on the display. A venti-
lated base design prevents damage to the bench or coun-
tertop.
Athree button control provides simple operation. Arrow
keys service to increase or decrease the furnace temper-
ature set point. A front panel Mode key allows the user to
toggle the display between set point temperature or actual
furnace temperature.

Selecting a Location
Choose a location for the furnace, which will provide an
area of approximately four square feet (2 ft x 2 ft). The
bench or table selected must be capable of supporting at
least 60lbs for the Model 14, 90lbs for the Model 58 or
110lbs for the Model 126. Appropriate electrical power
must be available. Locate the furnace within three feet of
the power outlet so that no extension cord is required.
It is recommended that the site have facilities for venting
an accessory Exhaust Tube Assembly (Cat. No.10-490-
10) which is available for use with the furnace.
Alternatively, the furnace may be located in a fume hood if
samples are expected to produce toxic volatiles.
Unpacking
Fisher Isotemp Muffle Furnaces are shipped in a single
carton. After unpacking, locate each item shown in the list
below. Report any missing items, by name and part num-
ber, to your Fisher branch or representative. In the event
of shipping damage, retain the carton and packing materi-
al and file a claim with the final carrier.
Item
Furnace Assembly
Model 14 120 V, 50/60 Hz
Model 14A 208/240V, 50/60 Hz
Model 58 208/240 V, 50/60 Hz
Model 126 208/240 V, 50/60 Hz
Hearth Plate
Shelf (Model 126 Only)
Instruction Manual
Warranty Card
5
Installation
Caution
Do not install closer than 6 inches
to a wall of combustible material.
Caution
Remove packing materials inside
chamber before operating.

6
Preparing the Furnace
To prepare the muffle furnace for operation, perform the
following procedures:
1. Make certain all packing material is removed
from furnace chamber.
2. Place hearth plate on the bottom of the cham-
ber. Orient hearth plate such that smooth sur-
face faces upward. See Fig. 1.
3. With the Model 126, the supplied shelf may be
used. If desired, install shelf by sliding it onto
top of ledge protruding from each side of the
inner chamber walls.
4. If installing the accessory Exhaust Tube
Assembly, first locate exhaust port at top of fur-
nace (see Fig 1). Use three screws to secure
the port flange to the exhaust port. Attach tub-
ing to port flange using a hose clamp (provided).
Finally, route free end of tube to fume hood or
other outside vent. If desired, exhaust tube may
be cut to length using a hacksaw.
INSTALLATION
Warning
Isotemp Muffle Furnace chambers
contain alumina silicate ceramic fibers.
With continued use at temperatures
above 1000°C (1832 °F), these materi-
als slowly convert to crystalline silica
(cristobalite). Long-term exposure to
airborne cristobalite may result in
severe respiratory diseases in
humans. Tests with laboratory animals
suggest that cristobalite is a possible
carcinogen. Short-term effects may
include irritation to skin, eyes and the
respiratory tract. Please consult the
Material Safety Data Sheet (MSDS)
provided by Fisher Scientific for further
information.
Warning
This unit is not explosion proof. Do
not use in the presence of flammable
or combustible materials; fire or explo-
sion may result. Unit contains compo-
nents that may ignite such materials.

Figure 1 – Furnace Layout
7
INSTALLATION
2
1
4
56
Hearth Plate
Thermocouple
Exhaust Port
7
1 Heater Indicator LED 5 Temperature Display Window
2 Mode Key 6 ON/OFF Power Switch
3 Increase Key 7 Door Switch
4 Decrease Key
See the following pages for keypad/display descriptions.

8
Operation
Power on Reset
When power is initially turned on to the furnace, the dis-
play will show “InIt” followed by the current furnace tem-
perature reading. The control display window shows furn-
cace temperature in °C.
Entering a Set Temperature
To enter a temperature setpoint, perform the following
steps:
1. With the power switch in the ON position, press
the Mode keypad. The display shows the latest
temperature setpoint.
2. In order to change the temperature setpoint,
press the UP arrow key to increase or the
DOWN arrow key to decrease. Once either key-
pad is pressed the decimal point will illuminate
to indicate a change in setpoint. Hold the
UP/DOWN keypad in until the desired setpoint
is reached.
3. Press the MODE keypad again or don’t press
any keypad for 3 seconds and the setpoint will
update with the setpoint indicated on the display.
Once the desired setpoint is entered, the heater indicator
LED will light and the chamber will begin to heat towards
the setpoint.
Setting the Display Offset
Isotemp Muffle Furnaces permit the user to calibrate the
temperature display and control point to a reference stan-
dard set up to read the interior furnace temperature at
any given point. With a display offset entered, the temper-
ature shown on the display will be actual furnace temper-
ature plus or minus the display offset selected.
To enter a display offset, carry out the following steps:
1. Place power switch in the OFF position.
Note
If no keypad activity occurs within 3
seconds, the display will return to the
temperature display mode.

2. While pressing the MODE keypad, place the power
switch in the ON position. The display now shows
the current offset value. The display offset values
are limited to a range of ±30°C.
3. Press and hold the UP arrow keypad to increase or
the Down arrow keypad to decrease the offset
value.
4. Press the MODE keypad again to enter the new off-
set value or wait 3 seconds and the new value will
automatically be entered.
When finished, the temperature display will be updated based
on the offset value entered. For example:
Example Offset
Adesired setpoint of 450°C. is entered and the furnace is
allowed 1 hour to stabilize to the setpoint. A reference temper-
ature is then measured inside the chamber to be 455°C. In
order to match the temperature display to the reference ther-
mometer, a display offset of 5 is entered. The temperature
display is then increased by 5°C and the display is in agree-
ment with the reference standard. The control will then cut the
heater ON time down so that the chamber cools by 5°C, thus
matching the desired setpoint.
Open Thermocouple
In the event the thermocouple becomes detached or broken,
the display will indicate so by showing “otc” (open thermocou-
ple). When this condition is encountered, the heaters are held
off. Repair or replace the thermocouple connection as needed
to clear the display.
Over Temperature Indicator
If the temperature in the chamber exceeds the setpoint by
100 C, the display will warn the user by flashing “HIGH” along
with the current chamber temperature. Also, the safety relay
will cut the heater circuit out and de-energize the heater.
Allow the unit to cool and the “HIGH” temperature alarm will
turn off when it falls to within 25°C of the setpoint. The con-
troller will then resume normal heater control.
OPERATION
Note
If no keypad activity occurs within 3
seconds, the display will return to the
temperature display mode.
9
Note
This condition can also be created by
decreasing the setpoint 100 C lower
than the current chamber temperature.

10
Service
Caution
Only qualified personnel should con-
duct service to the furnace.
WARNING
Always disconnect power cord from
the power supply before servicing
instrument.
All Fisher Isotemp 550 Series Muffle Furnaces use wall
heaters. The Model 550-58 and 550-126 also incorporates
a floor heater to maintain uniform heating. The following
sections describe procedures for replacing a heater or the
control thermocouple.
Replacing a Heater
To replace a defective heater, proceed as follows:
1. Disconnect power cord from the electrical out
let.
2. Open chamber door and allow door to remain
open throughout heater replacement.
3. Remove the screws that secure the perforated
metal back panel of the furnace main chassis.
Remove the panel and set it aside.
4. Loosen two heater terminal screws located on
the terminal barrier strip. Straighten the lead
screws.
5. Carefully withdraw the defective heater from the
chamber. Ceramic wool insulated surrounding
heater wires will fall into the furnace chamber.
Remove it and set it aside for later use.
6. Carefully install the replacement heater be
reserving the procedure in step 5 above.
7. Carefully re-attach the heater terminals by
reversing step 4. Then refill the holes around
heater leads with ceramic wool preserved from
step 5.
8. Re-install perforated metal back panel of the fur-
nace.
9. When the above steps are complete, return the
power cord to the electrical outlet.
Note
Allow chamber to cool to ambient tem-
perature before attempting repair.
Caution
Heater panel material is fragile.
Exercise care when inserting replace-
ment panels into the furnace chamber.
Likewise, bend or flex the heater leads
gently when necessary.