Laboratory Furnaces Overview – Operation, Features, and Applications
Laboratory Furnace Operation
Like most other furnaces, laboratory furnaces use a heat source to heat a sample within the furnace chamber. Convective heat transfer is the process used to heat the furnace and works by either gravity or mechanical convection.
In gravity convection, warmer air displaces cooler air and directs it towards the heating element until the entire chamber reaches the desired temperature. This method is known to have poor uniform heat distribution, a longer preheat time, and energy waste compared to mechanical convection. Mechanical convection laboratory furnaces use blowers and baffles in the furnace chamber, which helps to heat the chamber quicker and more evenly, making them a more popular choice.
Typical functions that laboratory furnaces perform are drying, where moisture is removed from the sample, baking, where a sample is heated without dehumidification, and curing, where the sample is chemically or physically altered.
Laboratory Furnaces Features
Laboratory furnaces can be built to perform a wide range of applications, and their range of features can be broad.
The size of the laboratory furnace is an important consideration. The volume of the furnace must be sufficient to suit the spatial needs of the samples being heated, and ideally, multiple samples should be accommodated. There are three main types of laboratory furnaces; benchtop, cabinet, and walk-in. Benchtop is the smallest furnace and walk-in are the largest.
The temperature of the laboratory furnace is another feature that can be altered when choosing the most suitable furnace. There are three different technologies that can be used to regulate the temperature within the furnace, including a thermostat, which has a simple on/off switch that engages the heating element to maintain a set temperature. Proportional control still uses a thermostat to monitor oven temperature, but heating is eased as it approaches the preheat vale to prevent overheating. PID control is a processor that calculates the amount of energy required to maintain the laboratory furnace at a set temperature and considers it against the heat loss, this method is typically the most energy efficient.
Depending on the application requirement, the air intakes and exhausts can be adjusted to release or withhold humidity, and they are also required to eliminate VOCs and fumes. Thermal insulation within laboratory furnaces improves efficiency as it reduces the rate of thermal transfer. These furnaces are typically made of steel, which helps to prevent any radiant heat from the oven exterior.
Laboratory Furnace Applications
Within the laboratory, furnaces are very versatile tools and are used for a wide range of applications. Typical applications include annealing, which is a process that improves ductility and malleability in metal samples. Laboratory furnaces can also be used for solvent removal, sterilizing, evaporation, polymer curing, and polyimide baking.
Laboratory Furnaces from Thermcraft
The eXPRESS-LINE of laboratory furnaces from Thermcraft is the perfect solution to many applications. They are available in box, split tube, and tube furnace configurations, and all provide excellent temperature uniformity.