THERMO SCIENTIFIC PR305225M (01) PDF Document

The THERMO SCIENTIFIC PR305225M uses the following alert signals to convey important 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 contact with a surface during use or for a period of time after use.

The specifications for the THERMO SCIENTIFIC PR305225M are as follows:

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

When unpacking your THERMO SCIENTIFIC PR305225M, follow these steps:

1. 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.

2. 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.

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.

Electrical Connection: The 120V unit is supplied with a 3-wire line cord with 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 PR305225M has 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 oven reverts to a safe operating range.

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

4. LED DISPLAY: Displays current chamber temperatures.

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

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

To operate the temperature control thermostat on your THERMO SCIENTIFIC PR305225M, follow these steps:

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

• 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 such factors as changes in line voltage, ambient conditions, and types of materials being heated.

• 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.)

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

A factory-set hi-limit thermostat 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 PR305225M, 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 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.

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.

Some Stainless Guidelines to Consider:

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.

The pH Factor:

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.

Chemicals which should be limited to a 3 hour maximum exposure time to stainless steel are:

Aluminum chloride	E.D.T.A.	Potassium permanganate
Barium chloride	Ferrous chloride	Potassium thiocyanate
Calcium chloride	Lysol	Sodium hypochlorite
Chlorinated Lime	Mercury salts	Stannous chloride
Citric acid (boiling)	Phenol	Tartaric acid
Dakin’s solution

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 rise.

• 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.

Materials effective in disinfecting the THERMO SCIENTIFIC PR305225M include:

• 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 THERMO SCIENTIFIC PR305225M 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 procedures should be performed only by authorized personnel. Unplug the unit from the power source. If the oven has been used recently, be certain that surfaces are safe to touch before attempting to carry out any of the following procedures. Remove contents of the oven and thermometer from the top of the unit.

Replacing Thermostat

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

• Remove back by unscrewing Phillips screws. Save.

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

• Remove bottom panel by unscrewing Phillips screws. Save.

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

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

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

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

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

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

• Next, pull bulb and tube through bottom hole.

• Thermostat, sensing bulb and tube assembly can now be removed.

• Reverse above procedure to install new thermostat.

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

Replacing Power Switch

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

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

• Compress holding tabs on switch and push out.

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

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

• Reverse remainder of procedure.

Replacing Status Lamp Bulb Assembly

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

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

• Grasp lamp unit and pull a fraction of an inch toward the attached wires. Lens will pop out the front. Save.

• Cut wires and remove lamp unit. Discard.

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

• Re-install lens.

• Re-install bottom plate.

Replacing HI-Limit Thermostat

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

• Hi-limit thermostat is mounted on back of inner chamber wall.

• Unscrew 2 screws and nuts holding wires. Save.

• Remove screw securing thermostat to back of inside wall.

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

Replacing Heater

• Heater is located in bottom of chamber. Be sure that unit has been turned off for a period of time, so that there is no residual heat on any of the surfaces.

• Remove back panel by unscrewing Phillips screws and save.

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

• Remove two retaining clips that mount heater to back of inside wall. Save.

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

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

• Install new heater and reverse the preceding steps.

Replacing Blower Wheel; Servicing

• Disconnect power cord.

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

• Remove Phillips screws holding shield that covers blower wheel.

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

• Replace the shield and shelves.

Replacing the Blower Motor

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

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

• Remove bottom cover, fan shield and blower fan.

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

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

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

• Reconnect wires.

• Re-install shelves. Make sure that 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.

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

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

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

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

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

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

• 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.

DESCRIPTION	PART NUMBER
Cordset, 120V	CR1483X1
Cordset, 240V	CR1483X2
Cordset, 240V China	CR1881X1
Door Catch	600-124-00
Door Handle	560-165-00
Fan, Axial (2)	160-136-00
Fan Shield	805-398-00
Feet, Rubber (4)	790-225-00
Fuse, 8 A,PR305220M, PR305220MCN (2)	790-225-00
Fuse, 15 A, PR305225M	330-298-00
Fuse Holder, PR305225M	330-297-00
Fuse Holder, PR305220M, PR305220MCN (2)	330-237-00
Gasket	530-196-00
Grommet (2)	790-247-00
Heaters:
PR305225M, 120V, 1200W	340-283-00
PR305220M, PR305220MCN, 240V, 1200W	340-296-00
Knob, Thermostat	560-223-00
Motor, PR305225M	MT1447X2
Motor, PR305220M, PR305220MCN	MT1447X1
Shelves Kit	3515M-8Q
Status Lamp Base (2)	360-233-01
Status Lamp Lens, Amber	360-235-00
Status Lamp Lens, Red	360-234-00
Switch, Power, 120V	SWX143
Switch, Power, 240V	440-292-00
Temperature Sensor, RTD	410-667-00
Thermometer, Digital	910-126-00
Thermostat, Control	920-223-00
Thermostat, Hi-Limit	920-413-00