Muffle furnace is mainly used for the determination of moisture, ash, volatile matter, melting point analysis, ash composition analysis, and elemental analysis. It can also be used as a general ashing furnace. It is also often useful in the lab of food, environment, pharmaceutical, and other industries.
Categories Of Muffle Furnace
The muffle furnaces have the following categories according to their heating elements, operating temperature, and controller.
1. According to heating elements
They can be categorized by electric furnace wire muffle furnace, silicon carbide rod muffle furnace, and silicon molybdenum rod muffle furnace.
2. According to the operating temperature
They can be divided into box muffle furnaces below 1000 °C, silicon carbide rod muffle furnaces with an operating temperature of 1100 °C-1300 °C, and silicon molybdenum rod muffle furnaces above 1600 °C.
3. According to the controller
They can be classified by PID regulation control muffle furnace with SCR digital display temperature controller, program control muffle furnace with computer temperature range controller.
4. According to thermal insulation materials
They can be categorized as refractory brick muffle furnaces and ceramic fiber muffle furnaces.
Precautions For Daily Maintenance of Muffle Furnace
- When the muffle furnace is used for the first time or again after a long-term shutdown, it must be dried. The oven drying time shall be four hours with a temperature of 200°C to 600°C. During use, the maximum furnace temperature shall not exceed the rated temperature to avoid burning the electric heating element. It is forbidden to pour various liquids and soluble metals into the furnace. The muffle furnace should preferably work below the maximum temperature of 50°C when the furnace wire has a long service life.
- The muffle furnace and controller must work in a place where the relative humidity is not more than 85% and there is no conductive dust, explosive gas, or corrosive gas. When metal materials With grease need to be heated, a large amount of volatile gas will affect and corrode the surface of the electric heating element, destroying it and shortening its life. Therefore, during heating, it is necessary to do prevention in a timely.
- The muffle furnace controller shall be used within the ambient temperature range of 0-40°C.
- According to technical requirements, regularly check whether the wiring of the electric furnace and the controller is in good condition. The temperature-measuring thermocouples connected to the controller may interfere with the controller, causing the phenomenon of measurement error. The higher the furnace temperature is, the more obvious this phenomenon is. Therefore, the metal protection tube of the thermocouple must be well grounded. If necessary, use a three-wire output thermocouple. In short, all effective measures should be taken to reduce interference.
- Do not suddenly pull out the thermocouple at a high temperature to prevent the explosion.
- Always keep the furnace clean and timely remove oxides and other things in the furnace.
- During use, when melting the sample or burning the sediment with alkaline substances in the furnace, the operating conditions should be strictly controlled. It is better to lay a layer of the refractory plate at the bottom of the furnace to prevent corrosion of the furnace chamber.
Safety Operation Procedures For Daily Use of Muffle Furnace
- Do not exceed the maximum temperature of the resistance furnace.
- Be sure to cut off the power supply when loading and taking samples to prevent electric shock.
- The opening time of the furnace door shall be as short as possible when loading and taking samples to prolong the service life of the muffle furnace.
- It is forbidden to fill any liquid into the furnace.
- Do not put the sample with water and oil into the furnace and don’t use clips with water and oil to take samples.
- Wear gloves when loading and taking samples to prevent scalding.
- The sample should be placed in the middle of the furnace and placed neatly.