THERMO SCIENTIFIC PR305220M (01) PDF Document

The THERMO SCIENTIFIC PR305220M uses the following alert signals to convey important safety information:

Warning: This signal alerts you to a possibility of personal injury.

Caution: This signal alerts you to a possibility of damage to the equipment.

Note: This signal alerts you to pertinent facts and conditions.

Hot Surface: This signal alerts you to a possibility of personal injury if you come in contact with a surface during use or for a period of time after use.

Power Requirements

PR305225M: 120 VAC, 50/60 Hz, 10 Amps, 1200 Watts

PR305220M, PR205220MCN: 240 VAC, 50/60 Hz, 5 Amps, 1200 Watts

Overall Dimensions

18-7/16″W x 15-9/16″D x 25″H (47 x 40 x 64 cm)

Chamber Dimensions

16″W x 11-1/2″D x 16″H (41 x 29 x 41 cm)

Volume

1.7 cu. ft. (48.1 liters)

Net Weight

65 lbs. (30 kg)

Temperature Range

All models, 5°C above ambient to 210°C.

Thermostat, Control

±5% over entire range.

Thermometer, Digital

±2°C over entire range.

Environmental Operating Conditions

Pollution Degree*: 2

Installation Category*: II

Altitude: 2000 Meters MSL (Mean Sea Level)

Humidity: 80% maximum, non-condensing

Electrical Supply: 120VAC or 240VAC

Voltage Tolerance: ±10% of normal rated line

Temperature: 15°C to 40°C

Product Usage: This product is intended for use indoors only

*Refer to IEC 664-1

Shipping Carton

The shipping carton should be inspected upon delivery. When received, carefully examine for any shipping damage before unpacking. If damage is discovered, the delivering carrier should both specify and sign for the damage on your copy of the delivery receipt. Open the carton carefully making certain that all parts are accounted for before packaging materials are discarded. After unpacking, if damage is found promptly report it to the carrier and request a damage inspection promptly. Important: Failure to request an inspection of damage within a few days after receipt of shipment absolves the carrier from any liability for damage. You must call for a damage inspection promptly.

Location

The oven should be located in an area free from drafts and sources of heat, as well as allowing for natural air movement to dissipate heat from the oven. Do not place oven on or near any combustible surface to avoid the possibility of fire and resulting property loss and injury or death to personnel.

Leveling

The oven should be on a level surface, in order to facilitate movement of materials into and out from the chamber.

Shelving

Slide shelves into place inside the oven and position according to the height required for the items or materials to be heated.

Important Cautions:

Do not remove the rubber space feet. Removal of the feet will prevent proper air venting (air used to cool the electronics is discharged out the bottom) of the oven chamber that may cause excessive heat buildup on electrical components and erratic control of temperature.

The bottom shelf is fixed in place to guard against access to the heater area and possibility of injury. Do not remove the bottom shelf unless performing maintenance or repair.

The 120V unit is supplied with a 3-wire line cord with a molded plug. It should be connected to a 120V outlet designed for 3-prong plugs. For an outlet designed to accept 2-prong plugs (ungrounded), the best advice is to have a qualified electrician replace it with a new, grounded outlet.

If a plug must be installed, use only the 3-prong grounded type, rated for the unit load requirements and matching the power outlet. Make sure the green ground wire is secured to the plug ground terminal.

The unit must be connected to a power source that meets the electrical requirements as specified on the unit’s nameplate.

Be Advised

Where it becomes necessary to make changes in electrical outlets, wiring and other characteristics, it is recommended that these be done by a qualified or journeyman electrician. This includes replacing 2-prong plugs (ungrounded), for example with a 3-prong plug (grounded). All changes need to be made to match the load requirements shown on the nameplate of the unit. It is best to leave the unit disconnected when not in use.

The control panel of the THERMO SCIENTIFIC PR305220M features the following components:

1. POWER SWITCH: Turns the unit on (green status lamp lights) and off.

2. HI-LIMIT STATUS LAMP: Lights when the hi-limit thermostat is activated. It goes out when the oven reverts to a safe operating range.

3. CALIBRATION POTENTIOMETER: Utilizing a jeweler’s screwdriver, the temperature readout can be adjusted. Labeled “OFST”.

4. LED DISPLAY: Displays current chamber temperatures.

5. TEMPERATURE CONTROL (THERMOSTAT): Raises and lowers temperatures.

6. HEATERS STATUS LAMP: Lights when heaters are energized.

Follow these steps to operate the temperature control on your THERMO SCIENTIFIC PR305220M:

1. With the temperature control thermostat (5) in the extreme counterclockwise position, turn the power (rocker) switch (1) to its on position. The switch’s green status lamp will light.

2. Turn the temperature control thermostat (5) in a clockwise direction to increase the temperature and counterclockwise to lower it. The amber status lamp (6) above the thermostat goes on when the heaters are energized. Wait for the chamber temperature to stabilize before advancing the thermostat too rapidly to reach the target temperature. Note that the dial setting to obtain a specific temperature will need to be approximated and can be affected by factors such as changes in line voltage, ambient conditions, and types of materials being heated.

3. Read the LED display (4) for the chamber temperature produced by each setting of the temperature control thermostat (5). As experience is gained with the temperature control thermostat, improved results will be obtained in setting it to achieve specific target temperatures.

4. Always allow time for the oven to reach the target temperature and to stabilize before making further adjustments of the temperature control thermostat.

Caution: At higher temperatures, the exterior of the oven and particularly the vent ring on the top of the oven become warm to the touch. To avoid burns, do not touch these surfaces.

A factory-set hi-limit thermostat on the THERMO SCIENTIFIC PR305220M cuts off power to the heater in the event that the maximum operating range is exceeded. The red status lamp (2) on the control panel indicates when the hi-limit thermostat is controlling. It goes out when the oven reverts to a safe operating range.

To clean your THERMO SCIENTIFIC PR305220M oven, follow these guidelines:

The bottom shelf that covers the heater can be removed for easy access to the heater area.

Clean up any spills as soon as possible to prevent materials from being baked on surfaces. When the oven is cool, use a mild soap and water to clean surfaces. Rinse thoroughly and dry. It is best to avoid highly abrasive cleaners which can damage the finish of the interior surfaces and shelves.

The Alloy called Stainless

Stainless steel is an alloy of steel with chromium and nickel that increase the metal’s resistance to rust and corrosion. Yet, if not properly cared for, stainless steel can rust and corrode.

Exposure to air provides the passivation, or oxide layer coating, for clean stainless by producing a thin, durable chromium-oxide that forms rapidly on the alloy surface to give stainless its characteristic “stainless” quality. Also exposure of the surface to other oxidizing environments can produce a passivating film or coating.

However, if free oxygen is not available due to scale or contamination buildup the metal surface may become vulnerable to rusting and corrosion as well as pitting. But by maintaining neutral pH and conducting frequent cleanings with detergent and water, years of trouble-free service from stainless steel products can be obtained.

Warning: Electrolysis can damage stainless steel. This occurs when an object is allowed to rest directly on the surface of stainless steel, trapping moisture that becomes oxygen-starved, but is surrounded by water-containing oxygen.

Distilled water is recommended. Please note: if this water is very pure it may be corrosive to stainless. When filling a bath or incubator, always add 2 to 40 PPM (20 to 40 mg/liter) disodium phosphate or sodium bicarbonate, adjusting dosage to provide a pH value of 7 to 9.

If not available, use clean, aerated soft tap water provided the total solids concentration is < 500 PPM.

We do not recommend using 18 MEG OHM deionized water. If this is the only source of treated water available, mix with regular tap water at a 50/50 ratio.

Check pH regularly. If pH is <6.0, add disodium phosphate to increase pH to a 7 to 9 value. Sodium carbonate or sodium bicarbonate may be used but they tend to form scale that must be rinsed out regularly. If pH is >10.0, add sodium bisulfate to decrease pH to a 7 to 9 value. Avoid adding harsh alkalines or acids since these may cause localized corrosion and result in unstable pH.

Yes. If it is necessary to use the following chemicals, limit exposure time to a maximum of 3 hours and always clean surfaces immediately after use.

Be advised: Never use the following on stainless steel:

Aqua regia

Ferric chloride

Iodine

Sodium acid

Sodium azide

Chemical spills, especially those agents listed here, should be removed as soon as possible and the stainless steel surface cleaned with mild soapy water followed by a clean water rinse.

Cleansing Agents

Anti-fungal and anti-bacterial additives are permissible to use as long as the pH of the aqueous solution is kept within the range of 7 to 9. These are available through laboratory distributors; be sure to confirm that they are not harmful to stainless steel.

Cleaning Methods

Do not use any metallic pads. Instead, for stubborn stains, use a plastic light-duty cleansing pad and rub gently in the direction of the metal grain. If stains continue to persist, use one of the following chemicals and methods.

• Any of a variety of “scale removers” available at local supermarkets or hardware stores used for the cleaning of coffee marks, humidifiers or vaporizers.

• A 15% to 35% phosphoric acid solution available from laboratory supply distributors for scale and rust removal. Allow solution to soak the surface affected until rust and scale is loosened. Immediately follow with a clean water rinse.

• Citric acid based cleaners.

• Bathroom tub and tile cleaners.

Regardless of the approach utilized, always follow the manufacturer’s directions and allow the chemicals to do the cleaning with minimal scrubbing. Always follow cleanings with a clean water rinse. Air dry.

The following materials are effective in disinfecting:

• Glutaraldehyde

• Alcohol

Be Advised: This information is intended as guidelines only and we make no claim as to the suitability to any particular situation. Consult your staff chemist to determine what would be best for your stainless steel product and laboratory.

If the oven fails to heat, there are several possible causes:

• The oven is not receiving electrical power.

• The heater is burned out.

• The thermostat is malfunctioning.

Have a qualified electrical technician determine the cause of the problem and make the necessary repairs.

The following should be performed only by authorized personnel. Unplug the unit from the power source and ensure surfaces are safe to touch.

1. Lay unit on its side with door latch facing down.

2. Remove back by unscrewing Phillips screws. Save them.

3. Carefully remove insulation. Note how it is positioned, so that it can be easily reinstalled.

4. Remove bottom panel by unscrewing Phillips screws. Save them.

5. Remove control knob by unscrewing 2 Allen-head screws. Save them.

6. Disconnect wires from thermostat. Note the position of wires for subsequent reattachment in the same sequence.

7. Knob removal allows access to 2 screws that mount the thermostat to the panel. Remove the screws and save them.

8. Remove the bottom shelf inside the chamber. Loosen the screw on the clamp that holds the thermostat-sensing bulb to the heater. Note the position of the temperature sensing bulb, so that the new one can be clamped in the same location.

9. Slide the bulb toward the exit hole at the back of the unit.

10. Move to the back of the unit and pull the temperature sensing bulb and tube through the hole.

11. Next, pull the bulb and tube through the bottom hole.

12. The thermostat, sensing bulb, and tube assembly can now be removed.

13. Reverse the above procedure to install a new thermostat.

14. Avoid making sharp bends in the temperature sensing tube; otherwise, the flow of temperature sensing fluid will be impeded.

The following should be performed only by authorized personnel. Unplug the unit from the power source and ensure surfaces are safe to touch.

1. With the unit on its side as in the preceding procedure, remove the bottom plate and save the screws.

2. Disconnect wires from the switch. Note the sequence of pin numbers on the side of the switch and the attachment of wires. The replacement switch must be oriented in the same manner and wires attached in the same sequence.

3. Compress holding tabs on the switch and push it out.

4. Insert the new switch from the front. When inserting, follow the same orientation of pin numbers as on the switch just removed.

5. Attach wires in the SAME SEQUENCE as originally attached. To verify that the correct sequence has been followed, refer to the wiring schematic.

6. Reverse the remainder of the procedure.

The following should be performed only by authorized personnel. Unplug the unit from the power source and ensure surfaces are safe to touch.

1. With the unit on its side, remove the bottom plate and save the screws.

2. Note the plastic lamp unit that houses the bulb. Be alert that the lens will pop out in the next step.

3. Grasp the lamp unit and pull it a fraction of an inch toward the attached wires. The lens will pop out from the front. Save the lens.

4. Cut the wires and remove the lamp unit. Discard it.

5. To install the new pilot lamp unit, splice the two wires of the assembly to the previously cut wires using insulated crimp connectors.

6. Re-install the lens.

7. Re-install the bottom plate.

The following should be performed only by authorized personnel. Unplug the unit from the power source and ensure surfaces are safe to touch.

1. Remove the back panel and carefully remove the insulation for subsequent reinstallation. Save.

2. The hi-limit thermostat is mounted on the back of the inner chamber wall.

3. Unscrew the 2 screws and nuts holding the wires. Save them.

4. Remove the screw securing the thermostat to the back of the inside wall.

5. Reverse the preceding procedure to install a new hi-limit thermostat.

The following should be performed only by authorized personnel. The heater is located in the bottom of the chamber. Be sure that the unit has been turned off for a period of time, so that there is no residual heat on any of the surfaces.

1. Remove the back panel by unscrewing the Phillips screws and save them.

2. Carefully remove the insulation and save. Note how it is positioned, so that it can be easily reinstalled.

3. Remove the two retaining clips that mount the heater to the back of the inside wall. Save them.

4. Remove wires to the heater by uncoupling the quick-disconnects.

5. Remove the bottom shelf inside the chamber. Loosen the screw on the clamp which holds the thermostat sensing bulb to the heater. Note the position of the temperature sensing bulb, so that a new one can be clamped in the same location.

6. Install the new heater and reverse the preceding steps.

The following should be performed only by authorized personnel. Disconnect the power cord before starting.

1. Remove the shelves. Note that the bottom shelf is retained by a clip at the back of the oven. Lift the shelf at the front edge until the back edge can be withdrawn from the clip.

2. Remove the Phillips screws holding the shield that covers the blower wheel.

3. Inspect the blower wheel assembly for tightness and any off-center operation. Inspect the blower wheel itself for damage to vanes or other deterioration. If the assembly is loose, tighten the setscrew holding the wheel to the motor shaft until the wheel turns true. If the wheel is damaged, replace it.

4. Replace the shield and shelves.

The following should be performed only by authorized personnel.

1. Disconnect the unit from the power source. If previously in use, let the unit cool down.

2. Lay the unit on its side. Remove the shelves, including the bottom one.

3. Remove the bottom cover, fan shield, and blower fan.

4. Accessing the unit from the bottom, remove the motor and bracket assembly. Disconnect the wires.

5. Remove the shaft extension, bottom fan, and motor bracket from the old motor and reinstall them on the new, replacement motor.

6. Re-install the motor assembly into the unit in reverse order of removal.

7. Reconnect the wires.

8. Re-install the shelves. Make sure that the bottom shelf is securely in place to prevent access to the heater area.

A temperature readout calibration potentiometer (3) is located in the upper left hand corner of the LED display and is indicated by the word, “OFST.” Use a jeweler’s screwdriver to make adjustments.

1. Have a digital thermometer, known reliable thermocouple (Type-K or -T) and the jeweler’s screwdriver on hand.

2. Insert the thermocouple sensor through the outside top vent hole and position it in the center of the oven chamber.

3. Set the oven temperature to a desired setpoint and turn on the power.

4. Allow the temperature to stabilize for at least 2 hours before making any adjustments.

5. Compare the chamber temperature on the digital thermometer to the temperature on the oven readout.

6. Insert the jeweler’s screwdriver in the calibration hole (OFST) and adjust the oven readout to match the thermometer reading. Turn the potentiometer clockwise to increase the reading and counterclockwise to decrease it.

7. Take two additional readings within an approximate 30-minute time span and make any necessary adjustments to the potentiometer. This takes into account any temperature variations that might exist within the oven and the time delay in responding to such factors by the temperature sensors.

Please refer to the Specification Plate for the complete model number, serial number, and series number when requesting service, replacement parts or in any correspondence concerning this unit.

All parts listed may be ordered from the Thermo Scientific dealer from whom you purchased this unit or can be obtained promptly from the factory. When service or replacement parts are needed we ask that you check first with your dealer.

Prior to returning any materials, you must obtain a “Return Materials Authorization” number (RMA). Material returned without an RMA number will be refused.