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How to Choose the Right Laboratory Oven? Step-by-Step Guide!

A decent laboratory oven can survive for many years of hard usage, therefore it’s worth taking the time to choose the ideal oven for your requirements. This blog post discusses some of the most critical aspects to look for when selecting an oven for aggregate, soil, concrete, or asphalt testing.

Testing Applications

Construction materials test applications employ laboratory ovens to dry materials at regulated temperatures and to heat asphalt materials for handling and testing. When heating aggregates, soils, and asphalt, it is critical to follow test methodology and avoid using excessive temperatures, which might affect their characteristics. Other industries utilize these ovens to heat treat, anneal, and condition metals and other materials.

Temperature Range

Maximum temperature ratings are an important factor when selecting a lab oven for your needs. You definitely need an oven with a maximum temperature equal to or slightly higher than the highest temperature specified in your test procedures. However, models with greater temperature ranges may not necessarily provide the best stability and uniformity performance at lower temperatures. Furthermore, these ovens may employ more expensive components and run at a higher cost.

Many oven models specify a minimum operating temperature. This is the oven’s lowest temperature to work to its specified specifications. When looking for an oven to test a range of materials using different test techniques, minimum temperatures are important to consider.

Types of Convection Ovens

Heat is delivered throughout a laboratory oven’s chamber using gravity convection or mechanical draft (forced draft) to heat its contents.

  • Gravity ovens rely on temperature and density variations in heated air to circulate throughout the chamber. This natural circulation can lead to lower temperature stability and homogeneity, as well as occasional dead patches in the chamber. 

Gravity convection ovens, on the other hand, are best suited for basic drying applications or situations where strong air currents may displace lightweight sample materials. They are frequently less expensive to acquire and run.

  • Forced-air ovens contain powered blowers that actively disperse air via customized baffles in the chamber, resulting in equal heating. Forced-air convection is useful for applications that demand multiple samples, increased moisture content, and a certain level of precision or consistency. 

Chamber Selection

Chamber volume and size are crucial considerations. The chamber must be large enough to fit the size and form of your samples, and you should consider how many samples you will need to load at one time. When you choose a chamber size based on a number that is too tiny, your workflow suffers. 

A chamber that is excessively big wastes lab space and increases operational expenses by heating the unoccupied chamber area. Externally, the oven must fit inside the available floor space and ceiling clearances, and it must be able to be moved in through available doorways. Most laboratory oven chambers are built to accommodate new shelves and rearrange existing shelves.

Stability

Uniformity and stability are important factors in lab ovens. Uniformity refers to the consistency of temperature across the chamber, while stability refers to the temperature range maintained by the thermostat or controller. Cold or hot spots can impact accuracy and test results. Reputable manufacturers will provide uniformity ratings for their laboratory and industrial models.

Energy Requirements

You should know the capacity and configuration of the electrical supply in your laboratory and the power requirements of the oven before purchasing. You may need to plan for electrical upgrades or modifications before installation. 

For some ovens, the amperage draw may be increased over the stated specifications during the start-up period. Gas-fired ovens may also be an option when large capacity chambers or continuous operations are anticipated, and when reduced uniformity can be tolerated.

Ventilation: 

If fumes from heated samples pose a risk in the lab, the oven exhaust should be evacuated outdoors. In certain situations, the laboratory oven can be placed beneath a sufficiently large fume hood, and many ovens have built-in ports for direct forced-air exhaust. Some types contain explosion-proof motors, which are necessary when working with very volatile compounds or vapors. 

Samples with a high moisture content may additionally require air to ensure proper drying performance. An HVAC specialist may be required to design and install an ideal ventilation system to ensure safety and effectiveness.

Recovery Time

Opening the oven door often to add or remove samples increases the system’s burden as it tries to compensate for lost heat. A rapid temperature recovery time is an advantageous performance attribute, although it necessitates greater energy. 

If your standards need a high level of consistency and precision, a quicker recovery time will be vital to you. Otherwise, heat loss may be effectively managed by reducing door opening frequency and maintaining an acceptable sample load in the chamber.

Materials

Laboratory ovens often use stainless steel interiors and shelves to prevent corrosion and degradation. If your materials are not especially corrosive, you may select a model with a plated or galvanized steel inside as a cost-effective choice. Ovens with double-wall construction and enough insulation between the chamber and the outer cabinet run more efficiently, and evenly, and have a cooler external surface for improved safety.

Control Options

There are several controller solutions available, ranging from simple analog dials with bimetallic thermostats to high-precision programmable digital PID controllers with data logging, calibration processes, self-diagnostic capabilities, and even remote web access. Pretty cool things, but you’ll need to weigh the expense of the features against the advantages. 

If you process a large number of samples per day or if your lab is “lightly staffed,” an oven with scheduled, automated, or even remote operation and temperature protection set points will be useful. If entry-level technicians will use the oven, perhaps simpler is preferable. The goal is to consider all available choices and make an educated conclusion.

We hope this blog post has helped you choose your new laboratory oven. If you need assistance with any of your applications, please contact Patel Heaters.

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