Fisher Scientific 282A User manual

Instructions
Fisher Isotemp
Model 282A
Vacuum Oven
Catalog No. 13-262-52 & 53
Manual PN 52063 (REV H)
Published 3/02
2000 Park Lane
Pittsburgh, PA 15275
[phone]

1
THE INSTRUMENT 2
Performance Characteristics 2
CONTROLS, INDICATORS AND CONNECTORS 3
CONNECTORS AND VALVES4
Site Requirements 6
Installation 7
OPERATION 8
Main Controller Menu 8
Table 2: Default Menu (Menu 1) 8
Key Entry 8
Table 3: Adjust Temperature Offset (Menu 2) 8
Key Entry 8
Table 4: Adjust Barometric Pressure Offset (Menu 3) 8
Key Entry 8
Table 5: Set Time and Day (Menu 4) 9
Key Entry 9
Table 6: Program Mode ON / OFF (Menu 5) 9
Key Entry 9
Table 7: Program Edit Mode (Menu 6) 9
Key Entry 9
Establishing Operating Conditions 10
TEMPERATURE/PRESSURE OFFSETS 12
CALIBRATION PROCEDURES 14
Calibration Routine 14
INIT-Initialize Memory 15
TCCB-Thermocouple Calibration 15
D/AC-Temperature/Vacuum Recorder Outputs 17
MAINTENANCE 17
SERVICE 21
Table 10: Trouble Analysis Chart 21
REPLACEMENT PARTS 22
SCHEMATICS 24
Figure 7: 115V Schematic 24
Figure 8: 230V Schematic 21

2
THE INSTRUMENT
The Fisher Isotemp® Vacuum Oven, Model 282A, is designed to operate with reduced pressures and/or with inert
atmospheres. As such, it is equipped with separate vacuum and gas ports--each has its own control valve.
Additionally, a special digital readout display indicates time of day, chamber temperature, pressure and schedules
for programmed oven operation.
Temperature settings and vacuum pump operation can be controlled at the touch of a button. A 7-day
programmable timer provides automatic temperature/vacuum control in real time programmable steps. The dual
displays provide constant day/time and temperature/pressure updates every 5 seconds. Chamber temperature
and pressure can be externally recorded by connecting to the recorder outputs located on the back of the control
board. PURGE and VACUUM valves, conveniently located under the control panel, provide access for a vacuum
pump and/or the presence of inert gases into the chamber.
The Model 282A design features a 1.5 cubic-foot stainless steel chamber with fully adjustable shelves. An
additional feature is a chamber door with full view, and tempered safety glass.
The stainless steel chamber permits performance of practically every laboratory need associated with general
drying, curing, conditioning, desiccating, annealing, and moisture tests. Additional applications include vacuum
embedding, out-gassing solids and liquids, aging tests, plating, and electronic process control.
Five built-in, self diagnostic features--open thermocouple, over temperature, power failure, low battery, and
calibration data corruption--on the front panel displays to alert the operator of a malfunction and thus prevent
damage to both samples and equipment.
Performance Characteristics
Temperature
Temperature Range ....................................Ambient to 280ºC continuously adjustable with 1ºC resolution
Heat Rise time............................................Ambient to 100ºC in <30 minutes, with temp set to 200°C.
Temperature Set-Point Accuracy .................<±2º C from 50 to 280°C
Cool-Down Time..........................................280 to 100ºC in approximately 2.5 hours
Temperature Set-Point Reproducibility.........±0.1ºC
Temperature Control Band..........................±0.2ºC
Long-Term (12 hours) Temp. Stability...........±0.03ºC
Temperature Display...................................3 digit LED display to nearest to nearest 1ºC
Average Temperature Uniformity……….………<±5ºC (in vacuum),based upon measuring points at the
geometric center and each corner of oven chamber at 100°C
Vacuum
Vacuum Pump Down Time...........................To <1 torr in 3 minutes using a pump having a free air
displacement of 100 LPM; 8 minutes using a 35 LPM pump
Average Leak Rate ......................................<1 inch Hg per 24 hours
Maximum Vacuum......................................Evacuates to <1 torr (0.039 inch Hg) absolute
Vacuum Display Accuracy...........................Average error 0.14 inch Hg between ambient and complete
vacuum
Atmosphere Control ....................................Use with non-corrosive, non-flammable gases such as nitrogen
and CO2
Power Requirements
Catalog No. 13-262-52.................................115V ±10%, 14.7 Amps, 50/60 Hz
Catalog No. 13-262-53.................................230V ±10%, 7.4 Amps, 50/60 Hz
Power Consumption.....................................1700 watts
Vacuum Pump Contacts (Tabs 3&4)..............1 HP @ 115 VAC, 2 HP @ 230VAC
Environmental:
Operating Temperature...............................60º to 100ºF
Storage Temperature ..................................32º to 120ºF

3
Humidity ....................................................20 to 80% relative humidity, non-condensing
Recorder Outputs
Temperature, Pins P3-1, P3-2.......................................................10 mv / °C
Chamber Pressure, Pins P3-3, P3-4...............................................100 mv / in Hg
Connector Type: AMP 640456-4
Physical Characteristics:
External Dimensions...................................26”W x 23”D x 22”H
Chamber Size .............................................12”W x 18”D x 12”H
Chamber Volume ........................................1.5 cu ft
SAFETY PRECAUTIONS
Before operation, always observe the following Safety precautions. This unit is not explosion proof. Do not use in
the presence of flammable or combustible materials; fire or explosion may results. Unit contains components that
may ignite such materials. Do not place volatile items in the chamber. Fumes and spillage from acidic solutions
cause corrosion of the stainless steel chamber. Care should be taken to maintain neutral pH at all times.
UNPACKING
Refer to the packing list below and be certain that all listed items are present. If any are missing, notify your
local Fisher branch or representative. Also, be certain to complete and return the included warranty card.
NOTE: If any shipping damage has occurred, retain the unit intact, including all packing materials, and file claim
with the final carrier. Usually, the firm will send an investigator to ascertain liability.
Table 1:
Packing List
Quantity
Description
1Model 282A Oven
2Shelves (shipped in chamber)
2Hose Connectors
1Instruction Manual
1Warranty Card
CONTROLS, INDICATORS AND CONNECTORS
Before putting the Model 282A into operation, the user should become thoroughly familiar with the location
and function of all controls, indicators, and connectors. Most are clearly labeled and located on or below the
front panel, with the exception of the two (PURGE and VACUUM) hose connectors, which are located on the
lower, right side of the oven. A set of vacuum pump auxiliary contacts and the temperature/vacuum recorder
output connectors are located on the rear side of the control board. See page 9 for instructions on accessing
these connectors.
The control panel consists of two 14-segment alphanumeric displays, six indicator LEDs, four keypads, and an
ON/OFF toggle. The VACUUM and PURGE valves are located just beneath the control panel. The list below gives
a more detailed explanation of each.
Figure 1: Control Panel

4
DAY/TIME DISPLAY: A four character alphanumeric readout that alternately displays the day of the week and
time of day in 5-second intervals.
TEMP/VACUUM DISPLAY: A four character alphanumeric readout that alternately displays the temperature (°C)
and chamber pressure (inHg) in 5-second intervals.
LED INDICATORS
AM: Indicates first 12-hour time is being displayed/programmed in the upper display window.
Flashes when in calibration mode.
°C: Indicates chamber temperature (°C) is being displayed/programmed in the lower display
window.
inHg: Indicates chamber absolute pressure is being displayed in the lower display window.
Also illuminated during vacuum pump program step.
Heater: Indicates heater activation.
Pump: Indicates closed vacuum pump contact condition.
Program: Indicates 7-day program setup or operation.
KEYPADS
Menu: Allows operator to cycle through main menu and calibration menu.
Set: Selects one of six main menu parameters and one of five calibration menu parameters.
Increase: Increments values to be selected for each parameter.
Decrease: Decrements values to be selected for each parameter.
CONNECTORS AND VALVES
POWER SWITCH: A rocker type switch that controls all power to the Model 282A Vacuum Oven.
VACUUM CONTROL Valve: A forged body, shut-off valve used to open and close the connection to an auxiliary
vacuum pump. Valve port accepts a supplied serrated fitting to ease in connecting a 1/4-inch (Inside diameter)
hose.
PURGE CONTROL Valve: A forged body, shut-off valve used to open and close the connection to an auxiliary gas
source. Valve port accepts a supplied serrated fitting for ease in connecting a 1/4-inch (inside diameter) hose.
VACUUM INLET Port: A serrated hose fitting used to connect an auxiliary vacuum pump to the oven. Fitting
accepts a 1/4-inch (inside diameter) hose.
PURGE INLET Port: A serrated hose fitting used to connect an auxiliary gas source to the vacuum oven. Fitting
accepts a 1/4-inch (inside diameter) hose.
VACUUM PUMP AUXILIARY CONTACTS: Normally open contacts located at the bottom of the rear side of the
control board (Tabs 3 & 4). The contacts close when either the pump is manually activated at the keypad, or by
running a program step that calls for pump activation.
TEMPERATURE AND VACUUM RECORDER OUTPUTS: Four pins located on the top, right of the rear side of the
control board (P3) which provide a voltage readout corresponding to chamber temperature and/or pressure.

5
Calibration Jumper Pin (JP4): Group of four pins located in the center of the rear of the control board. The lower
two pins when jumped enable calibration mode. See Figure 2 for controller rear view.

6
Figure 2: Control Board –Rear View
Recorder Outputs –P3
Calibration jumper JP4.
Shown in calibration mode.
Battery Module
Self Diagnostic Safety Monitors
A group of five messages alert the operator to heater and control malfunctions. The OTC (open thermocouple) and
OVR (over temperature) errors alternately display in the TEMP/VACUUM display. The PWRF (power failure), BATT
LOW (low battery) and CRC (calibration data corruption) are displayed in the DAY/TIME display window. All
messages and their meanings are as follows:
OTC (OPEN THERMOCOUPLE): The TEMP/VACUUM display alternates between OTC and current chamber
pressure at 5 second intervals, where OTC replaces the normal process temperature display field. The heaters
and vacuum pump (if connected to auxiliary contacts) are forced OFF. Program execution is halted.
OVR (OVER TEMPERATURE): Activates if oven temperature exceeds the setpoint + 20°C.
PWRF (Power Failure): Power failure only detected during program mode. The failure must be longer than 2
minutes. Time display alternates between PWRF, HH:MM and DAY(n) at 5 second intervals.
BATT LOW (Low Battery): Indicates it is time to replace the 6-year battery module. Module is in a socket on the
back of the control board. See Fig. 2.
CRC (Calibration Data Corrupted): Indicates an error in the stored calibration data. The heater and pump relay
are forced off. Unit must be calibrated to clear
INSTALLATION AND ASSEMBLY
The Model 282A is shipped assembled and ready for operation. However, before installing the oven, the operating
site should be prepared to meet necessary requirements. Additionally, a few assembly procedures must be
performed before the oven can be safely and properly operated.
Site Requirements
The standard plug configurations are shown in Figure 3. The 115VAC model is supplied with a 20 amp plug
(NEMA 5-20P). The 230VAC model is supplied with a 15 amp plug (NEMA 6-
15P). Verify that the appropriate
receptacle is at the location the oven will be used.

7
Figure 3: Standard Plug Configurations
The supporting bench or table must be capable of holding in excess of 200 pounds. The bench should be sufficient
to accommodate sample-handling processes. The oven itself is 26-inches wide and 23-inches deep; therefore, the
bench surface should be approximately 48-inches wide and 30-inches deep to allow for ventilation clearance at
the rear of the oven.
For installations that may use a tank atmosphere, check that site facilities and tank equipment are in compliance
with OSHA requirements for handling compressed gas. Responsible personnel must also be thoroughly
knowledgeable in the use, storage, and handling of compressed gases. Fisher Scientific carries a complete line of
accessory equipment for gas cylinders.
When using a tank atmosphere, a 1/4” tube to 1/4” pipe adapter is required for the regulator outlet of the tank.
This adapter is not supplied. A Swagelok B-400-7-4 adapter, or equivalent, may be used. Also, 9/16”, and 1-1/8”
open-end or, preferably, flare-nut wrenches are required.
Installation
After verifying all site and safety requirements, the following steps should be completed to prepare the vacuum
oven for operation:
1. Verify that all-packing items and securing materials have been removed from the oven.
2. Move the oven to the desired location as specified above.
3. Locate the two serrated hose fittings, packed in the INSTRUCTIONS envelope accompanying each oven.
4. Install the hose fittings on the VACUUM and PURGE ports located on the lower right-side panel. Hose fittings
should be installed by turning the fitting nut clockwise until finger-tight then, using a 9/16” wrench, turn the
nut an additional 1/4-turn while holding the fitting stationary with a 3/8” wrench.
5. Close both the PURGE and VACUUM valves by turning the control knob clockwise as far as possible.
6. Connect a vacuum pumping system, including a suitable trap, to the serrated fitting labeled VACUUM. Use
1/4-inch I.D. heavy-walled vacuum tubing and secure the connection with a hose clamp.
7. If desired, connect a purge gas supply to the serrated fitting labeled PURGE using a suitable length of 1/4”
I.D. tubing. Use a two-stage gas flow regulator if gas is to be supplied by a pressurized cylinder.
WARNING: To avoid the risk of fire, provide 6 inches of clearance for the top, back
and sides of the oven. Do not set or lean any objects against or on top of the oven while
hot.
WARNING: To avoid the risk of electrical shock, verify that the source plug is
properly grounded.
6
-
15P
5
-
20P

8
8. After installing connecting tubing, check that the PURGE CONTROL valve on the Model 282 is closed (full
clockwise position) then open the regulator flow control valve to pressurize the line. At this point, check all
connections for leaks using an ordinary soapy water solution.
9. Check data plate and plug line cord into a suitable power receptacle
OPERATION
Main Controller Menu
Energize the oven by switching the ON/OFF toggle to the ON position. The upper display will show VER while the
lower display will show 1.0, indicating the current software version. Next, the DAY/TIME display will begin
alternating between the day of week and the time of day. At the same time, the TEMP/VACUUM display will
alternate between chamber temperature (°C) and chamber pressure (inHg). Press the MENU key to scroll through
menus 1-6, then press SET to enter a menu. When there is no keypad activity for 5 seconds, the unit returns to
menu 1 automatically. The following table lists the main menus and their functions. The tables that follow list
the subcategories of the main menu and describe the function of each.
Table 1: Main Menu
MAIN MENU
Menu Prompt Display Functions Setup Functions
1 (Default) TopDisplay –Dayofweek,Timeofday
BottomDisplay –Temperature(°C),Pressure(inHg) Adjusttemperaturecontrolsetpoint TurnvacuumpumpcontactsOn/OFF
2 ADJT Displaytemperatureoffsetvalue Adjust temperaturecontroloffset
3 ADJP Displayspressureoffsetvalue Adjustforbarometricpressurevariations
4 TSET Displaysflashingdayortimevalue Setclockanddayoftheweek
5 PRGM Displaysprogrammode Start/Stopprogrammode
6 PSET Displaysday,stepandsetpoint Program 7–Dayeventtimer
Table 2: Default Menu (Menu 1)
Step Key Entry Action Display
1 Press SET Unit enters Temperature Setpoint mode with the currentsetpoint
displayed. Use the UP/DOWN keys to adjust the setpoint. SP: 280
2 Press SET 2nd Time The temperature setpoint is updated and the vacuum pump
ON/OFF option is displayed. Use the UP key to switch the
pump on, and the DOWN key to switch the pump off.
PUMP
OFF
3 Press SET or wait 2
seconds Unit returns to the default menu. MON 280
Table 3: Adjust Temperature Offset (Menu 2)
Step Key Entry Action Display
1 Press MENU until ADJT
is displayed, then press
SET
Use the UP/DOWN keys to adjust the temperature offset.
(Range +/-30 °C) ADJT 00
2 Press SET or wait 2
seconds Unit returns to the default menu. MON 280
Table 4: Adjust Barometric Pressure Offset (Menu 3)
Step Key Entry Action Display
1 Press MENU until ADJP
is displayed, then press Use the UP/DOWN keys to adjust the pressure offset. (Range +/-8.0 inHg) ADJP 0.0

9
SET
2 Press SET or wait 2
seconds Unit returns to the default menu. MON 280
Table 5: Set Time and Day (Menu 4)
Step Key Entry Action Display
1 Press MENU until TSET
is displayed, then press
SET
Unit enters set time and day mode and the current hour and
minute is displayed. Hours digits are flashing. Use the
UP/DOWN keys to adjust the hour.
08:00
AM•
2 Press SET Minutes digits are flashing. Use the UP/DOWN keys to adjust
minutes. 08:00 AM•
3 Press SET Day of the week is displayed (flashing). Use the UP/DOWN
keys to adjust the day of the week. MON
4 Wait 2 seconds Unit returns to default menu. MON
280
Table 6: Program Mode ON / OFF (Menu 5)
Step Key Entry Action Display
1 Press MENU until
PGRM is displayed,
then press SET
Use the UP/DOWN keys to switch the program on or off.
PGRM OFF
2 Press SET or wait 2
seconds Unit returns to the default menu. MON 280
Table 7: Program Edit Mode (Menu 6)
Step Key Entry Action Display
1 Press MENU until PSET
is displayed, then press
SET
Unit enters the program edit mode and points to MONday, step
1. Use the UP/DOWN keys to select the day and step.
MON1
2 Press UP or DOWN,
then press SET. Unit displays the program time for the current step. Hour digits are flashing. Use the UP/DOWN keys to adjust hour. 08 : 00 AM •
3 Press SET Minutes digits are flashing. Use the UP/DOWN keys to adjust
minutes. 08 : 00
AM •
4 Press SET Step time and temperature setpoint is displayed. Setpoint is
flashing. Use the UP/DOWN keys to adjust setpoint. 08 : 00 280
5 Press SET Program step time and pump status is displayed. Pump ON or
OFF is flashing. Use the UP/DOWN keys to switch pump ON or
OFF.
08 : 00
OFF
6 Press SET Unit displays the program day, step and ‘N ?’ prompt. Use the
UP/DOWN keys to adjust prompt to Y to accept or N not accept.
08 : 00
N ?
7 Press SET, then MENU
to exit or SET again to
continue
Unit displays the next program step. To exit the edit session
press MENU, or press SET to view or edit another step. MON2

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8 Press MENU to exit Unit displays COPY/NO. This option will copy 8 steps
forward to each day through the end of the week. Use the
UP/DOWN keys to adjust prompt to Y or N.
NO
Establishing Operating Conditions
Establishing the operating conditions consists of setting the desired temperature program and establishing the
desired environmental conditions, e.g., vacuum, inert gas atmosphere, or both. Instructions pertaining to
connecting a vacuum pump and/or gas supply to the oven are given under the INSTALLATION AND ASSEMBLY
section of this manual. Before establishing conditions, be certain that all steps given under the aforementioned
section have been completed.
Auxiliary Pump Contacts
The following procedure describes the proper method used for operating a vacuum pump using the auxiliary
contacts
supplied on the control board (Tabs 3 and 4).
NOTE: Vacuum pump operation can be performed independently as well.
1. Remove power cord from the supply outlet.
2. To access the auxiliary contacts, remove six screws holding the right side panel in place.
3. Pull the back edge of the side panel away from the oven and slide the front edge out the front panel slot.
4. Remove the hole-plug located just to the right of the VACUUM port. The keyed hole is properly sized to
support a UL/CSA type SR 7W-2 strain relief bushing to be used with 18/2, 18/3, 16/2, 16/3 type S or ST
cable. Verify the cable is long enough to reach the pump contacts, then fasten the cable in the keyed hole
with a strain relief bushing.
Figure 4: Accessing Pump Contacts
5. Crimp two ¼” push-on connectors to the two cable wires. Connect one wire to Tab3 and the other to Tab 4.
The pump circuit should be connected as shown in Fig. 4.
6. Reattach the side panel using the six side panel screws.
WARNING: High voltages are present when the side panel is removed. Only trained
personnel should conduct this procedure.

11
7. Connect the vacuum hose to the Vacuum Inlet Port on the side of the oven and open the Vacuum valve. Close
the door and the Purge Inlet Port by turning Purge valve clockwise completely.
8. Plug the oven in and switch the ON/OFF toggle to the ON position. The top and bottom displays will
alternately flash between time of day/day of the week and chamber temperature/pressure, respectively.
9. Press the SET key until PUMP is displayed in the upper display window. Press the UP ARROW key. The lower
display window should show ON. Press the SET key again or leave as is for two seconds. The contacts will
close and the pump should turn on. Control will then revert to the default mode after five seconds.
10. While the pump evacuates the chamber, the chamber pressure should begin to drop as indicated by the lower
display. The bottom display alternately shows chamber pressure (in Hg) and chamber temperature (°C).
11. To turn off the pump, press the SET key until PUMP is displayed in the upper display window. Press the
DOWN ARROW key. OFF should then be displayed in the lower display window. Press SET or leave as is for
two seconds. The auxiliary pump contacts will open and the pump should turn off.
As noted above, the vacuum pump can be controlled as described or manually using an external switch.
Setting the Temperature
To set the oven temperature, begin by pressing the SET key. The upper display will show SP while the lower
display indicates the last set temperature or OFF, indicating the heaters are turned off. Next use the UP/DOWN
arrow keys to toggle through temperature values. When the desired temperature is displayed, press the SET key
to enter the value. Return to the default mode by continuously pressing MENU or leave as is for two seconds and
control will revert to the default mode automatically.
NOTE: If fast warm up is desired, the temperature must be set at approximately 25ºC higher than the final
temperature, then set back to the final temperature when the oven reaches a temperature within 10ºC of the
final temperature.
Operation in a Static Environment
Static environment is defined as operation at atmospheric pressure and with air--as it is present. In this case,
the operator would simply place the sample in the oven chamber and set the desired temperature.
Operation in a Controlled Environment
Controlled environment is defined as operation with the samples in an inert gas. To accomplish this, perform the
following:
1. Place samples in the oven chamber then close and lock the chamber door.
2. Close the PURGE CONTROL valve (full clockwise rotation).
3. Open the VACUUM CONTROL valve (full counterclockwise rotation) then turn on the vacuum pumping system
to remove any air remaining in the oven.
4. Close the VACUUM CONTROL valve and open the PURGE CONTROL valve slowly to bleed in an inert gas.
5. Close the PURGE CONTROL valve, then set the desired temperature and process time.
Operation in a Vacuum Environment
To operate the oven in a vacuum environment, perform the following:
1. Place samples in the oven then close and lock the oven door. Verify that gasket seal has been coated with
high temperature vacuum grease.
2. Close both the PURGE CONTROL and VACUUM CONTROL valves.
3. Turn on the vacuum pumping system then open the VACUUM CONTROL valve (full counterclockwise rotation).
4. The vacuum, in inches-of-mercury, can be read on the TEMP/VACUUM Display.
CAUTION: The maximum allowable current in the auxiliary circuit is 6 amps. See
page 2 for contact ratings before applying power.

12
Temperature/Pressure Offsets
When the oven reaches a stable operating condition, the display temperature should indicate the actual center
chamber temperature (+/-2.0°C). In the event a more accurate display reading is needed, the offset parameter,
locatedin the MAIN MENU, can compensate for the error. To enter an offset value, press the MENU key until the
upper display window shows ADJT (adjust temperature) then press UP/DOWN arrow keys to enter an offset for the
display temperature. Press the MENU key 5 times to return to the default display or wait for 2 seconds and
control will shift automatically.
EXAMPLE: The oven is temperature is set for 200°C. After it has reached a stable state (usually 2½ hours for
200°C) the actual temperature of the oven center, as read by a certified thermometer, is 203°C. The oven display
shows 200°C. Entering a +3 for the ADJT parameter will move the display to agree with the actual oven
temperature.
NOTE: Adjusting the offset only changes the display temperature. It does not alter the controller operation.
The vacuum display can be adjusted in the same way. In the event the displayed chamber pressure is not
accurate, press the MENU key until the upper display window shows ADJP (adjust pressure). Use the UP/DOWN
keys to enter the desired offset. Press the MENU key four times to return to the default display or wait for 2
seconds and control will shift automatically. The displayed chamber pressure will be updated with the offset
value.
Setting the Time and Day
To set the time and day press the MENU key until the upper display shows TSET (time set). Press the SET key
and use the UP/DOWN arrow keys to adjust the hour of the day. When the current hour is displayed enter it by
pressing the SET key again. Use the UP/DOWN arrow keys to adjust the minutes. When the correct minutes are
displayed, press the SET key. Finally, days of the week can also be adjusted by pressing the UP/DOWN arrow
keys. Press the SET key again to enter the day of the week.
PROGRAMMING THE OVEN
The oven controller is capable of handling 8 instructions per day, 7 days a week. Programming the controller is
not difficult. Table 7, listed as MENU 6 –Program Edit Mode, provides step by step instructions for setting the
control temperature and/or vacuum pump operation at any given time of day or day of the week. Use Table 7 in
conjunction with the following description when programming the oven controller
To enter the Program Edit Mode press the MENU key until the upper display shows PSET. The upper display will
then show MON1, indicating the first step in Monday. Use the UP/DOWN arrow keys to step through to the
current day of the week. When the desired step is reached press SET. Use the UP/DOWN arrow keys to adjust
the starting hour of the current step, press SET to select the desired hour. Repeat for minutes, temperature and
vacuum pump operation. The next prompt (N ?) asks the user to copy the current step to the remaining steps in
the day. Use the UP arrow key to select Y (yes), or leave as is and select no by pressing the SET key. The upper
display will then shift to the next step, MON2 (if MON1 was the previous step). Repeat this procedure for entering
new steps.
If a step was copied to the end of the day, that same day can also be copied to the end of the week. To do this,
press the MENU key when the next step appears in the upper display window. At that point, press the MENU key.
The upper display will show COPY, while the lower display shows NO. Use the UP arrow key to change the NO to
YES. Press the SET key and the previous day’s program is copied to the end of the week.
NOTE: The program week begins on Monday and ends on Sunday.
Sample Program:
Monday:
1. Evacuate chamber and operate at 100°C for 5 hours starting at 8AM. Maintain less than 5 in Hg during the 5
hours.
2. Increase temperature to 150°C and operate for 2 hours. Maintain same chamber pressure.
3. Shut down oven for remainder of day.
Tuesday:
Repeat steps from Monday except step 2. Have oven shut down after 100°C operation.
Wednesday:

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Repeat Tuesday.
Thursday:
Repeat Monday.
Friday:
Repeat Monday.
Using the information on page 8, MENU6, the program could be set up as shown on page 12.
SAMPLE PROGRAM ARRAY
STEPS M
ONDAY
TUESDAY WEDNESDAY THURSDAY FRIDAY SATURDAY SUNDAY
1 Temp: 100°C
Pump: ON
Time: 8:00AM
Temp: 100°C
Pump: ON
Time: 8:00AM
Temp: 100°C
Pump: ON
Time: 8:00AM
Temp: 100°C
Pump: ON
Time: 8:00AM
Temp: 100°C
Pump: ON
Time: 8:00AM
Temp: OFF
Pump: ON
Time: 12:00AM
Temp: OFF
Pump: ON
Time: 12:00AM
2 Temp: 100°C
Pump: OFF
Time: 8:10AM
Temp: 100°C
Pump: OFF
Time: 8:10AM
Temp: 100°C
Pump: OFF
Time: 8:10AM
Temp: 100°C
Pump: OFF
Time: 8:10AM
Temp: 100°C
Pump: OFF
Time: 8:10AM
Temp: OFF
Pump: ON
Time: 12:00AM
Temp: OFF
Pump: ON
Time: 12:00AM
3 Temp: 150°C
Pump: OFF
Time: 1:00PM
Temp: OFF
Pump: OFF
Time: 1:00PM
Temp: OFF
Pump: OFF
Time: 1:00PM
Temp: 150°C
Pump: OFF
Time: 1:00PM
Temp: 150°C
Pump: OFF
Time: 1:00PM
Temp: OFF
Pump: ON
Time: 12:00AM
Temp: OFF
Pump: ON
Time: 12:00AM
4 Temp: OFF
Pump: OFF
Time: 3:00PM
Temp: OFF
Pump: OFF
Time: 1:00PM
Temp: OFF
Pump: OFF
Time: 1:00PM
Temp: OFF
Pump: OFF
Time: 3:00PM
Temp: OFF
Pump: OFF
Time: 3:00PM
Temp: OFF
Pump: ON
Time: 12:00AM
Temp: OFF
Pump: ON
Time: 12:00AM
5 Temp: OFF
Pump: OFF
Time: 3:00PM
Temp: OFF
Pump: OFF
Time: 1:00PM
Temp: OFF
Pump: OFF
Time: 1:00PM
Temp: OFF
Pump: OFF
Time: 3:00PM
Temp: OFF
Pump: OFF
Time: 3:00PM
Temp: OFF
Pump: ON
Time: 12:00AM
Temp: OFF
Pump: ON
Time: 12:00AM
6 Temp: OFF
Pump: OFF
Time: 3:00PM
Temp: OFF
Pump: OFF
Time: 1:00PM
Temp: OFF
Pump: OFF
Time: 1:00PM
Temp: OFF
Pump: OFF
Time: 3:00PM
Temp: OFF
Pump: OFF
Time: 3:00PM
Temp: OFF
Pump: ON
Time: 12:00AM
Temp: OFF
Pump: ON
Time: 12:00AM
7 Temp: OFF
Pump: OFF
Time: 3:00PM
Temp: OFF
Pump: OFF
Time: 1:00PM
Temp: OFF
Pump: OFF
Time: 1:00PM
Temp: OFF
Pump: OFF
Time: 3:00PM
Temp: OFF
Pump: OFF
Time: 3:00PM
Temp: OFF
Pump: ON
Time: 12:00AM
Temp: OFF
Pump: ON
Time: 12:00AM

14
8 Temp: OFF
Pump: OFF
Time: 3:00PM
Temp: OFF
Pump: OFF
Time: 1:00PM
Temp: OFF
Pump: OFF
Time: 1:00PM
Temp: OFF
Pump: OFF
Time: 3:00PM
Temp: OFF
Pump: OFF
Time: 3:00PM
Temp: OFF
Pump: ON
Time: 12:00AM
Temp: OFF
Pump: ON
Time: 12:00AM
The default settings for any step are: TEMP-OFF, PUMP-OFF, and TIME-12:00 AM. The outlined areas above
indicate actual program editing. Notice the final step programmed for each day is copied through to the end of
that day. This was accomplished by selecting Y (yes) at the ‘?’ menu (see MENU6, Step 6).
Program Execution Enabling/Disabling
To execute a program, press the MENU key until the upper display shows PGRM. Press the UP key to display ON,
then press SET or wait 2 seconds and control will return to the default mode automatically. The program will then
search for the current day and begin execution at the most recent step.
To stop program execution, press the MENU key until the upper display again shows PRGM. Press the DOWN
arrow key to display OFF, then press SET or wait 2 seconds for the program to stop automatically.
CALIBRATION PROCEDURES
The Model 282A Isotemp® Vacuum Oven is carefully calibrated before leaving the factory. However, re-calibration
will be necessary when component parts are repaired or replaced. This is especially true regarding the vacuum
readout system. In fact, it may be necessary to re-calibrate this system if critical vacuum levels are required to
meet particular applications due primarily to altitude and atmospheric conditions.
Calibration Mode
Follow the instructions below to access the calibration mode:
1. Set the POWER switch to the OFF position.
2. Remove the right side panel from the Model 282A.
NOTE: Refer to instructions for removing the side panel on page 9 before proceeding.
3. Locate two sets of jumpers on the back of the control board labeled JP4. To enter the calibration mode,
remove the bottom jumper and place it across the bottom pins as shown in Figure 2, page 5.
4. Set the power switch to the ON position. The upper display will show INIT, which is the first calibration menu.
By pressing the MENU key repeatedly, all calibration menus can be viewed in the upper display. Table 8
summarizes the calibration menus.
NOTE: Any part of the calibration can be conducted individually without altering data from the others.
5. To abort a calibration and return to the control mode, simply set the power switch to the OFF position and
remove JP4 before completing a calibration. The previous calibration data will not be affected.
Table 8: Calibration Menus
Prompt Calibration Routine Comments
INIT Initialize data memory. Four options. Selectively clears data variables,
program and clock. Resets all calibration data to
defaults.
TCCB Measure and Control
thermocouple calibration. Requires two temperature points (T2 –T1) > 100°C. temperature control loop is on during
calibration.
VCMC Pressure sensor. Requires two pressures, ambient plus second point
near 0 in Hg.
D/AC Temperature and vacuum
recorder outputs Adjust full scale. Temperature, vacuum inputs not required.
CJCD Cold junction compensation
temperature Display for verification only. No adjustment

15
INIT-Initialize Memory
The INIT menu allows the operator to selectively clear data stored for program, calibration and/or clock functions.
To select one of the functions, simply press the SET key when the upper display shows the INIT menu. Next, use
the UP/Down arrow keys to select which data to clear. The choices are as follows:
1. VAR Miscellaneous Variables
2. PRG Program Data
3. TIM Time Data
4. CBR Calibration Data
Finally, with the desired data type displayed in the lower display, press the SET key again to reset the data to the
factory set values. The lower display will show CLR indicating the data has been cleared.
TCCB-Thermocouple Calibration
Before beginning the temperature calibration, place a NIST calibrated thermometer in the center of the vacuum
oven chamber and close the door. Press the MENU key until the upper display shows TCCB, then press the SET
key. The unit enters the thermocouple calibration mode and displays the first temperature set-point (flashing).
Use the UP/Down arrow keys to select the desired temperature. Press the SET key to accept the first desired
calibration point. Allow the unit ample time to reach each set point. A 50°C calibration point will take
approximately 2 hours to stabilize. When the chamber temperature has completely stabilized, record the
temperature of the thermometer in the chamber center. Using that value as the reference, use the UP/DOWN
keys to match the oven display temperature to the reference temperature. Press the SET key. The controller will
WAIT and SAMPLE values for the low end calibration, then displays the second temperature set-point (flashing).
Use the UP/DOWN arrow keys to adjust the desired second set-point. Press the SET key to enter the second set-
point. Allow the unit time to heat and stabilize at the second set-point. When the unit is stable, record the
temperature of the reference thermometer. Adjust the display to match the reference thermometer using the
UP/DOWN arrow keys. Press the SET key. The controller will then SAMPLE this data. When the controller is
finished, the next menu will appear (VCMC).
VCMC-Vacuum Calibration
Before calibrating the vacuum readout system, it is necessary that the barometric or atmospheric pressure be
known. One way of doing this is to contact the U.S. Weather Bureau in the installation area. The bureau will
provide the barometric pressure corrected to sea level, this pressure must then be corrected to the altitude where
the calibration will be performed. This can be done by interpolating the data from Table 9. Once a pressure for
the calibration altitude is obtained, the value is subtracted from the sea level value on Table 9 to obtain the
correction factor. The correction factor will then be subtracted from the value obtained from the bureau.
Obviously, the corrected value obtained will be only as accurate as the accuracy to which the exact elevation is
known.
Example: The barometric pressure corrected to sea level, as reported by the U.S. Weather Bureau on June 13,
1983, was 30.19 In. of Hg, in Pittsburgh, PA. The elevation at the calibration site, also in Pittsburgh, is 850 ft.
above sea level. Interpolating the data from Table the pressure at 850 ft. is 29.02 In. of Hg; subtracting this value
from 29.92 (sea level pressure) gives a correction factor of 0.9. The actual pressure at the calibration site is:
30.19 -0.9 = 29.29 In of Hg.
Another method is to read the pressure directly from a temperature compensated barometer that can be adjusted
for altitude. This method will give the pressure at the elevation of the calibration site without the need for any
additional calculations or corrections. Generally, the pressure value measured should fall within the 29 to 30
inches-of-mercury range. In fact, measurements outside this range should be suspect.
Slight variations will exist usually because of pressure variations due to weather conditions. Therefore, the most
accurate way to calibrate the Model 282A vacuum readout system is to first obtain the atmospheric pressure using
one of the methods above.
NOTE: The procedure below for calibrating the vacuum display assumes the vacuum pump is being controlled
by the Auxiliary Contacts, Tabs 3 & 4. The vacuum display can be calibrated with manual pump operation,
as well.
To calibrate the vacuum display perform the following:
1. While in the VCMC calibration mode, open the vacuum (full-CCW) valve to expose the chamber to atmospheric
pressure.
2. Connect a suitable vacuum pump to the PURGE port along with a vacuum gauge as shown in Figure 5.
Figure 5: Vacuum Pump Hook-Up

16
Mcleod
Vacuum Gauge
FSCO 10-269-27
To Vacuum Sensor
3. Press the SET key to enable vacuum calibration. The upper display will show PRSR with the AM LED flashing.
The lower display will indicate 29.0 in Hg.
4. Use the UP/DOWN arrow keys to set the displayed pressure to match the atmospheric pressure.
5. Press the SET key again to enter the value. The controller will sample the pressure and adjust the display to
it. Note: The controller will sample the vacuum data, then it will automatically close the auxiliary vacuum
pump contacts for the second-point calibration.
6. Rotate the PURGE valve about two turns counterclockwise from the closed position
7. Rotate the VACUUM valve to the full clockwise (closed) position.
8. Allow time to for the pump to evacuate the oven chamber as much as possible (about 10 minutes).
9. After vacuum equilibrates, read the vacuum gauge (McLeod) and convert the reading from millimeters to
inches-of-mercury (divide by 25.4 mm/inches).
10. Using the UP/DOWN arrow keys, adjust the vacuum display to match the reading converted from the
reference gauge (in Hg).
11. Press the SET key. The controller will sample the vacuum data, then indicate when it is done.
12. If it is desired, check for chamber leakage by rotating the PURGE valve to the full clockwise position. Leakage
should be less than 0.5 inch-of-mercury in one hour.
13. Open the VACUUM valve (rotate counterclockwise) and allow air to bleed into the chamber.
14. Verify the atmospheric pressure is shown in the lower display. Repeat the procedure if necessary by pressing
the MENU key until the upper display again reads VCMC.
Pressure
Altitude (ft.) Inches of
Hg
Torr
(mm of
Hg)
PSI
-1000 31.02 787.87 15.25
-500 30.47 773.83 14.94
Sea Level (0) 29.92 760.00 14.70
500 29.38 746.37 14.43
1000 28.86 732.93 14.18
1500 28.33 719.70 13.90
2000 27.82 706.66 13.67
2500 27.31 693.81 13.41
Table 9: Pressure at Atmosphere; Source U.S. Standard Atmosphere, P.62 (NASA)

17
3000 26.81 681.15 13.19
3500 26.32 668.69 12.92
4000 25.84 656.40 12.70
4500 25.36 644.30 12.45
5000 24.89 632.38 12.23
5500 24.43 620.65 12.00
6000 23.98 609.09 11.77
6500 23.53 597.70 11.56
7000 23.09 586.49 11.34
7500 22.65 575.45 11.12
8000 22.23 564.58 10.90
8500 21.81 553.88 10.70
9000 21.38 543.34 10.50
9500 20.98 532.97 10.30
10000 20.58 522.75 10.10
D/AC-Temperature/Vacuum Recorder Outputs
Connector pin P3 is the Temperature/Pressure Recorder Output interface. Output pins P3-1 and P3-2 provide an
output voltage proportional to the chamber temperature, while the pins P3-3 and P3-4 provide a similar voltage
proportional to the chamber pressure. To begin calibrating the Recorder Outputs, press the menu key until the
upper display shows D/AC, then press the SET key. The lower display will show CAL and then enter the
temperature D/A calibration (D/AT). Connect a voltmeter across output pins P3-1 (+) and P3-2 (-). The upper
display will show a number that corresponds to the temperature output voltage. Use the UP/DOWN arrow keys to
adjust the corresponding display value to increase or decrease the temperature output voltage then press the SET
key to enter the new value. The output voltage will be updated. Repeat the process until the voltmeter indicates
+3.00VDC. Press the MENU key to accept the new calibration data and enter the vacuum pressure recorder
calibration, indicated by D/AV in the upper display.
To begin calibrating the vacuum pressure recorder output, move the voltmeter leads to output pins P3-3 (+) and
P3-4 (-). The lower display again indicates a number corresponding to the vacuum recorder voltage. Use the
UP/DOWN arrow keys to increase or decrease the vacuum output voltage then press the SET key to enter the new
value. The output voltage will be updated. Repeat the process until the vacuum output voltage is +3.00VDC.
When complete, press the MENU key to accept the data
The calibration is complete when both displays indicate DONE CAL.
CJCD-Cold Junction Compensation Temperature Display
The cold junction calibration is a self-calibrating procedure. To initialize the CJCD process, press the SET key
when the upper display shows CJCD. The upper display will then indicate CJC with the lower display showing the
cold junction temperature. There is no adjustment to be made, simply press the SET key again to conclude the
calibration. The next menu to appear in the upper display is the INIT menu. Remove the jumper at JP4 to return
to normal operating mode (see step #5 under Calibration Mode).
MAINTENANCE
The Model 282A is constructed and finished with materials that provide long maintenance-free service. All that is
normally required is a routine cleaning of the exterior surfaces, oven shelf, and oven floor. Use a mild detergent
for this purpose. Additionally, all external line connections for inert atmospheres should be checked for tightness
on a weekly basis. The oven door seal should also be visually checked for deterioration such as cracks or loss of
flexibility. A good seal is necessary to assure proper operation of the instrument.
WARNING: Secured access panels, covers, etc., should never be removed from this equipment by anyone other
than experienced service personnel. Hazardous line voltages are present at various internally exposed points.
Fisher maintains fully staffed service centers at all major Fisher branches to assist with any service problems. A
separate section is included in this manual for qualified service personnel.

18
Door Alignment Procedure
A good seal around the door is critical, particularly when operating the oven with a vacuum environment.
Therefore, the following procedure should be performed carefully. Refer to the illustrations shown in Figure 6
and perform the following.
1. Loosen, but do not remove, the four (two in both the top and bottom hinge) screws securing the door hinges.
2. Loosen the three door bracket screws (located next to the control panel) that hold the bracket to the cabinet.
3. Slide the bracket all the way to the right. Securely tighten the three screws.
4. Loosen the two slide-adjust nuts on the bracket and slide the catch outward.
5. Align the top door edge parallel to the top surface of the chassis to within 1/16 inch.
6. Draw a vacuum by pressing on both left and right sides of the door using your hands. Close vacuum valve at
25 inches of Hg.
7. Tighten the two bolts for each hinge while lightly pressing each corner of the door in the area of the hinge
being tightened.
8. Slide the cam assembly to engage the catch, and then turn the handle down so that the flat on the cam is
vertical. Push gently on the catch until it touches the flat on the cam.
9. Insert a 1/32-inch thick shim (not supplied) between the catch and flat side of cam, and securely tighten the
two nuts on the catch while applying vacuum.
10. Remove the shim. Then release vacuum and open door.
11. Try cam mechanism for clearance of both door edge and cam. If there is a clearance of more than 1/16 inch
between the end of the cam and catch projection, adjust spacing by loosening the three catch screws and
readjust catch.
12. Secure the three screws and check clearance of step 11. Check that oven door positively seals after
completion of this procedure.

19
Figure 6.1 –6.6: Door Alignment