Knowledge - Climate

Drying ovens and heating ovens are both devices used in laboratories and industrial applications to dry, heat or stabilise materials. Although they have similar functions, there are still differences between the two:

1. Drying chamber:
A drying chamber is mainly used to remove moisture from materials. This typically takes place at temperatures of 40°C to 150°C, depending on the load capacity of the sample. Depending on the model, air from the surroundings is heated with or without a fan and drawn into the chamber. There it absorbs the moisture from the sample material and is released into the environment via an exhaust pipe. At high temperatures and high air exchange, drying is faster than at low temperatures and low air exchange.

Vacuum drying ovens are available for particularly sensitive materials that are damaged at higher temperatures. The boiling point of the material to be vaporised is lower due to the vacuum. The drying process is gentler on the material. The vacuum also helps to draw moisture out of small cavities.

2. Heating chamber:
A heating chamber, is used to heat materials to higher temperatures. The temperature ranges in a heating chamber can vary greatly depending on the model and application. Heating chambers are often used for processes such as sterilisation, ageing tests, material testing and other thermal treatments. In contrast to the drying oven, the focus here is less on removing moisture and more on temperature treatment.

Drying ovens and heating ovens therefore do not differ in the appliance model, but in their intended use.

To summarise, drying ovens are used for drying materials at an elevated temperature. Vacuum drying ovens are used for drying at a moderate temperature. Heating ovens are used for thermal applications where higher temperatures are required.

Constant climate chamber:
A constant climate chamber, also known as a climate chamber or climate simulation chamber, is used to simulate constant climate conditions such as temperature and humidity. These cabinets are used to test materials under defined environmental conditions to observe their response to changes in temperature and humidity. This is particularly important in industries such as electronics, pharmaceuticals, food and material sciences. A constant climate chamber can create both simple and complex temperature and humidity profiles to simulate specific environmental conditions.

Environmental simulation chamber:
An Environmental simulation chamber, also known as a climate test chamber or environmental test chamber, goes beyond constant climate simulation. This chamber allows the simulation of a wider range of environmental conditions, including not only temperature and humidity, but also factors such as lighting, vibrations, shock loads and other mechanical influences. Environmental simulation chambers are used to test the resistance of products to more complex environmental conditions that may be encountered in real applications. This is particularly important in the development and testing of products that have to meet certain environmental standards.

In summary, a constant climate chamber is mainly aimed at simulating temperature and humidity conditions, while an environmental simulation chamber can simulate a wider range of environmental factors to test the performance of products under more realistic conditions.

–> Constant climate chambers
–> Environmental simulation chambers

A malfunction of an oven can lead to overheating, which can damage the product or damage the oven itself. To prevent this, be sure to take the following precautions:

1. If the set temperature is too high, set the temperature limiter about 10 % above the desired temperature to protect the sample.
2. If the temperature limiter is set too low, set it to a higher level to avoid overheating.
3. If the temperature limiter is defective, the next safety limit is the temperature limiter to protect the device, which is usually set at the factory about 20 degrees Celsius above the maximum achievable temperature of the device.

BINDER units are equipped with a temperature selector limiter (TWB), which prevents the unit, its surroundings and the load from being exposed to impermissible temperature overshoots. In the event of a malfunction of the temperature controller, the TWB switches the unit off automatically.

The TWB is designed to be functionally and electrically independent of the temperature control unit and switches the unit off permanently. When the TWB is set to the end stop, it acts as unit protection. If it is set slightly higher than the setpoint temperature set on the controller, it serves as a device fuse.

If the temperature limiter switches off, it is essential that the cause of the malfunction is investigated and rectified by a specialist.

Commonalities:

• Temperature range RT+10°C to +300°C
• Very good temporal and spatial temperature accuracy
• Up to 30% more energy-saving than conventional units on the market
• Controller with LCD display and USB interface for data recording via USB stick, temperature ramp function
• Integrated temperature selection limiter class 2 with visual alarm
• 2 slide-in grids included
• Electromechanical control of the exhaust air flap

ED:

• Natural convection (no fan or forced air circulation)
• Timer function: Time-delay OFF
• Interfaces:
  • USB port for data recording

FD:

• Forced convection with fixed fan speed
• Timer function: Time-delay OFF
• Interfaces:
  • USB port for data recording

FED:

• Forced convection with adjustable fan speed
• Timer functions: Time-delayed OFF, Time-delayed ON, Temperature-dependent delayed OFF
• Interfaces:
  • USB port for data recording
  • ETHERNET (communication with APT-COM software)

The airflow

The new airflow of the Avantgarde.Line™ was developed in cooperation with a Swiss university and is the result of simulation calculations with the aim of achieving the most even temperature distribution possible in the interior. In this design, the heated air is blown into the inner chamber through slits in the back wall, close to the side walls. The end result is a very homogeneous temperature distribution and very good insulation to the outside. Consequently, the energy requirement is also minimal. The exhaust air flap in the rear wall is opened and closed electrically in several intermediate positions.

In the Classic.line™, the air is drawn off to the rear by the fan, guided under the inner chamber and blown out of the side wall into the interior via deflectors.

Further details on the patented APT.line™ can be found here, on the BINDER page (german).

The door handle

In the Classic.Line™, the slightly cranked door handle corresponds to doors in the building sector. In horizontal position the door is closed, in 45° position downwards the door is open. In the Avantgarde.Line™, the door handle is arranged vertically in the closed position. In the 45° down position, it is open. This may be a little unusual, but the feel is very pleasant.

The controller

Where the slider for the exhaust air flap is located on the Classic.Line™, there is a socket for a USB stick on the Avantgarde.Line™. With the stick inserted, time-temperature data can be recorded.

Drying process:

1. Starting with ambient pressure, the pressure initially drops.
2. Depending on the vapour pressure of the solvent, a plateau phase is then reached.
3. Once the solvent has completely evaporated, drying is complete. The pressure begins to drop again.
4. Without drying monitoring, the pressure would now drop further…
5. until the maximum ultimate vacuum is reached.
6. The drying monitor recognises this second pressure drop. It switches off the pressure control. The appliance is now automatically ventilated.

In a pressure cooker, water is brought to the boil but the resulting steam is prevented from evaporating. Because only a small amount of water is added, the temperature rises to over 100°C relatively quickly. The pressure increases until temperature and pressure reach equilibrium. For safety reasons, excessive pressure is blown off via the valve. With the steam pressure present (usually between 1.4 and 1.8 bar), the vegetables are cooked at a temperature of 120 to 130°C. This is faster than if they were cooked in an open pan at 100°C. In other words, faster than if it were cooking in an open pot at 100°C.

In an open pot, the temperature remains stable as long as there is still water in the pot. Only when there is no more water does the temperature continue to rise. However, the vegetables are normally removed long before this effect occurs.

In the vacuum drying oven, water (or another solvent) is also brought to the boil or vaporised. If, for example, a damp cloth is heated to 80°C and a vacuum of 100 mbar is created (10 times lower pressure than in the environment), the water will evaporate. As the resulting vapour is continuously extracted, a negative pressure remains. In this case too, an equilibrium is formed with the vapour pressure until no more water is present. After that, the pressure drops further, or in other words, the vacuum increases.

The advantage of vacuum drying is the lower temperature at which the solvent evaporates. This makes it gentle on the goods to be dried.

Commonalities:

Languages: German, English, French, Spanish, Italian.

Both controllers regulate the temperature (°C or °F) and the pressure (mbar or psi).

There are the password levels ‘Every user’, ‘User’, ‘Administrator’ and ‘Service’. Access to the basic functions can be set at user level with or without a password.

RD4

This is the standard controller for the VD model series vacuum drying ovens with development status E3.1.

The desired setpoints can be entered on the controller in the ‘Setpoints’ menu or on the PC using the APT-COM™ 4 Multi Management Software (optional) specially developed by BINDER.
The controller offers various status and alarm messages with visual and acoustic indication.
All controller settings are valid until the next manual change. They remain saved even after the device is switched off

MB2

Compared to the RD4, this controller has extended functionality, particularly with regard to display and programming. The VD series appliances can alternatively be ordered with the MB2 controller. The MB2 controller is standard in the VDL model series with development status E3.1.

Weekly and time programmes can be programmed. A timer programme (stopwatch function) is also available.

The controller offers various status and alarm messages with visual and audible indication and remote alarming via e-mail, an event list and a graphical view of the measured values in the chart recorder display. With the MB2 programme controller, temperature and pressure cycles can be programmed and special controller functions can be specified for each programme section. The setpoints and programmes can be entered directly on the controller or via the APT-COM™ 4 Multi Management Software (optional) specially developed by BINDER on a PC.

• Fixed value operation
  The controller operates as a fixed value controller, i.e. set values can be entered for temperature and pressure, which are then regulated until the next manual change.
• Timer programme mode
  Stop timer function: For the duration of an entered time, the controller constantly regulates to the setpoint values entered in fixed value mode.
• Time programme operation
  An entered time programme for temperature and pressure is executed. The controller has 25 programme memory locations, each with 100 programme sections. The sum of the programme sections of all programmes is not limited.
• Weekly programme operation
  An entered weekly programme for temperature and pressure is executed. The controller has 5 programme memory locations, each with 100 switching points. The switching points can be distributed over all days of a week.

Behaviour during and after a power failure: If a vacuum is present and ventilation is required for the duration of the power failure, this is possible via the emergency ventilation. When the power supply is restored, the last setpoint values entered are equalised.

Temperature change rate according to DIN EN IEC 60068-3-5

The temperature change rate is a characteristic value for the performance of a temperature change or climate change test chamber. The change times are usually determined in accordance with DIN EN IEC 60068-3-5. This takes into account that 10% of the performance range of the system is not included in the calculation.

For a measurement from -70°C to +180°C, the total curve is 250 K. The temperature range is reduced by 10% (25 K) at the upper and lower end of the test curve. This means that only the range from -45°C to +155°C is taken into account to determine the rate of change (on the empty device).