STANDARD OPERATING PROCEDURE: High Temperature Box Furnace  

Oregon State University, Department of Chemistry
Standard Operating Procedure (SOP): Safe Use of High Temperature Box Furnaces (ver. 1.0)
Author: Mas Subramanian (mas.subramanian@oregonstate.edu)
Safety Web Inception Date: 3/01/2010
Revised: N/A

Chemistry Department Safety Office: Gilbert Hall Room 153
Emergency Medical Services: 911
Campus Student Health Center: 7-9355
Poison Control: 9-1-800-222-1222
OSU Environmental Health and Safety: 7-2273
Campus Security: 7-7000

 
   

A. Introduction

General: This type of apparatus uses high temperatures during operation. High temperature furnaces use high voltage to generate temperatures above 500°C. Do not open the furnace or remove any substrates until the oven and its contents have cooled sufficiently for safe handling. Be aware that materials may not glow or appear hot under 600 °C.

Heating Elements: The furnaces operate to a maximum temperature of 1100-1600 °C. Ramp up and ramp down rates are relative (1 hour to many hours depending on synthesis procedures). It should be noted that prolonged heating at temperatures below 1000 °C can cause damage to the MoSi2 heating elements. This is because MoSi2 oxidizes to SiO2 and weakens the elements at temperatures in the range of 400-800 °C.

Melting Points: It is helpful to know the approximate melting temperature of your material. If you are unsure, a sample container should be used which can contain your sample in a melted form. This is necessary because it helps to protect the furnace insulation from contamination and damage. The insulation is very expensive to replace.

Quenching: Quenching of samples from high temperatures can be extremely dangerous! This procedure should never be performed alone and should be done so using additional protective equipment including high temperature gloves, long handled tongs, full face shields and flame proof jackets. This procedure should be minimized, however, as it also can damage the insulation and heating elements. In the event of a fire, the standard fire protocol should be followed.

Sealed Tubes: When it is necessary to heat sealed tubes, the quality and melting point of the tube should be checked. Sealed tubes heated in the furnace can explode and cause serious damage to furnace and/or cause serious injury to the user if the explosion occurs during sample removal. Additional protective equipment is required including a full face shield, gloves, lab jacket and tongs.

This SOP should be read and understood prior to the commencement of relevant work and used to complement supervised practical familiarization with the various techniques described. MSDS for any materials to be heated must also be consulted before starting work. MSDS are easily found from supplier websites, or are available in hard-copy form in many Gilbert Hall laboratories (e.g., in Gilbert 202 near the east entrance).

 
   

B. Hazard identification, required safety equipment (PPE, engineering controls), and emergency response

B1. Hazards: High voltage is needed to generate temperatures greater than 500 °C. With the high voltage come inherent dangers of electrocution, fire, and severe burns. Make sure the furnace is properly grounded and no loose wires are connected to the furnace and wear all necessary protective clothing while operating. The furnace program should be stopped, or the furnace shut off before opening the furnace door. Working with high temperatures between 200 – 1600 °C; materials will not always glow or appear hot, but will cause severe tissue damage with improper handling.

B2. Personnal protective equipment (PPE): Before using the furnace, ensure that at least the following protective equipment is available to you:-

1. Safety glasses
2. Thermal gloves
3. Aluminized heat resistant jacket (if possible, especially for quenching)
4. Closed-toe shoes with socks
5. Long pants (no shorts!) 
6. Lab coat
7. Face shield
8. Safety mask (when necessary)

B3. Engineering controls: There are no ventilation controls for the furnaces. Most box furnaces have muffles which allow gasses to escape. All furnaces should therefore be placed in fume hoods, and each fume hood should be checked for proper flow. Consult your advisor, or the supervisor for your lab if there is no fume hood or you are unsure about the proper use for the fume hood. If you are treating a material which could pose a health risk special precautions must be adhered to.

B4. Emergency response in the case of spill or other accident: If you drop your sample on the work bench and it catches fire, remain nearby, and follow “Oregon State University Fire Instructions.” If you accidentally drop the sample on yourself don’t panic! Remain calm. Immediately go to the sink and rinse with cold water to try and reduce the burn. If a fire occurs because of the sample, leave the room and contact technical staff; if the fire is out of control engage the fire alarm for the building; and contact emergency response 911, then EH&S at 7-2273, stay nearby to provide information to responders.

 
   

C. Procedures for safe operation of box furnace

C1. Before commencing work: Any person using the high temperature furnaces must be trained by one of the technical staff of the Department of Chemistry prior to using the equipment. Under ordinary circumstances it is not allowed for you to work with the high temperature furnaces while being alone in the laboratory. Always ask a second person to be in the lab with you. If you have to work with a high temperature furnace and you are alone, you must ask for approval from your supervisor and the supervisor of the lab where the furnace is located.

C2. Preventing contamination: If there are any spills, make sure the area is cool, then clean up with paper towel or a broom and mop. You must adhere to current disposal laws and protocols. Upon leaving a designated work area, remove any personal protective equipment worn and wash hands. After each use (or day), wipe down the immediate work area. At the end of each project, thoroughly decontaminate the designated area before resuming normal laboratory work in the area.

C3. Precise process description: The following step-by-step instructions provide an overview of furnace operation.

C3.1. Setup
• Open the door and load the sample in the furnace.
• Close the oven door. There is an audible click when the door is closed completely.


C3.2. Operation
• Turn on the main power by flipping the green switch on the front of the furnace.
• After a five second boot, the display will show two numbers. The top green number is the actual temperature of the oven set-point can be checked by pressing either the up or down button once.
• Use the up and down arrows below the digital display to set the temperature setpoint.
• See appendices 1-4 (below) for specific furnace program instructions
• A light is lit when the heating elements are engaged.


C3.3. Shutdown
• Once the process is complete, adjust the temperature setpoint so that the temperature is below room temperature if the program set hasn’t already. This will ensure that the heating elements will not be engaged.
• Monitor the temperature as the furnace temperature decreases.
• The materials can be removed once a low temperature is reached. The cool down time will depend on the process temperature and may be much longer than the actual process time.
• Once the furnace is cool, the material may be removed. Use the stainless tweezers to move the alumina boat, if needed.
• Turn off the main power to the furnace.

 
     

D. Appendices

The following links provide specific furnace program instructions.

1. Appendix 1: Barnstead/Thermolyne 21100 Tube Furnace [LINK]

2. Appendix 2: Thermolyne 6000 [LINK]

3. Appendix 3: Lindberg Tube Furnace [LINK]

4. Appendix 4: Carbolite CWF 135 [LINK]

 
   
This chemical safety advisory document was prepared solely for the use of researchers affiliated to Oregon State University. As stated above (Section A), the content is designed to inform on good working practices and it is not intended to replace hands-on practical training in the techniques described. It is the responsibility of the Principal Investigator to see to it that his/her co-workers are properly trained and informed on hazard management, including the possibility of customization of the information herein as appropriate to meet specific needs. Neither Oregon State University, nor any of its employees (including the author), makes any warranty, express of implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, or represents that its use would not infringe privately owned rights. Reference herein to any specific commerical product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by Oregon State University.