Many laboratories use ovens to heat, dry, age, degas, cure or condition samples.
Lab ovens are usually available as natural convection or fan assisted – we’ve taken a look at when you would choose each type to help you pick the right oven for the task.
Ovens with fan assisted convection offer two main advantages;
As the fan moves the air around the chamber constantly, the uniformity around the chamber is generally better in fan assisted ovens. This means the temperature varies less when taken across different points within the chamber.
For example, in a UF110 Fan oven at 100°C, the uniformity is ±1.2 °C, while in the UN110 Natural Convection oven at 100°C the uniformity is ±2.2 °C.
Faster Heating and Recovery
Having fan assistance means that initial heating time and recovery time (after opening the door) is reduced.
For example, it takes 21 minutes for a UF110 Fan oven to heat up to 100°C, while it takes 50 minutes for the UN110 Natural convection oven to reach the same temperature.
This is also seen in recovery times – with the UF110 taking 12 minutes to recover to 100°C, but the UN110 taking 16 minutes.
Usually an oven with natural convection would be chosen only in specific conditions;
Suitable for Powdered samples
If you are working with powder samples which may be easily disturbed by the fan convection, then a natural convection model should be chosen.
This is particularly important if the powders are hazardous.
Warming without strong evaporation
When you need to keep samples at an elevated temperature, but are not specifically trying to dry them out, a natural convection oven may be preferred.
The gentler air movement does not encourage evaporation at such a strong rate, so could be preferred if over-drying is a concern.
Application drives the decision
Overall we would recommend most people to choose a fan assisted oven, moving to a natural oven only if it is specifically preferred.
Many fan assisted models, including the Memmert UF range of ovens, can have the fan turned off, so there is still flexibility if you want to work with natural convection only on some occasions.
For more information about laboratory ovens, both fan and natural convection types, follow the links above or contact us if you have any questions;