A pharma oven or pharmaceutical oven, is a high-tech equipment that provides a fast and economical way for drying materials in laboratories and pharmaceutical industries. In most cases, you can dry fresh herbs, granules or powders.

Pharmaceutical oven come in a wide range of sizes, designs and capabilities. The complexity of a machine will depend on its capability, functionality and design.

Below is an example of a pharmaceutical oven:

SaintyCo GMP Hot Air Circulation Oven

In this article, you’re going to learn about 8 important aspects of pharma ovens. These are the key aspects I have learnt after reviewing over 15 different types and designs of pharmaceutical ovens.

The article is tailored for both newbies and professionals in the pharmaceutical and food processing industry. More importantly, those who use heating ovens in their daily applications.

#1: Classification of Pharmaceutical Ovens

Generally, you can categorize the available pharmaceutical ovens based on many factors such as size, functionality, working principle, design, nature of applications, technology, etc.

In this section, I will review some of the most common types of pharma ovens in the market.

But first, let me make this point clear:

At times, some people refer to these machines either as drying ovens or moisture extraction ovens.

Is there a difference between the two?

No, drying and moisture extraction ovens refer to the same equipment. Remember, drying ovens are basically used to remove moisture from granules, wet powder or herbs.

Ideally, drying ovens have a variable and controlled temperature option. This facilitates evaporation and helps in the rapid drying of materials by forced convention.

Forced convention in ovens

Don’t worry, you will learn more about this later in this article when I’ll be exploring the working principle of pharmaceutical ovens.

For now, let’s review the various types of pharmaceutical ovens:

The Exact Application of the Oven

In this category, you may opt for either industrial or laboratory ovens. Although the ovens may have different applications, the principle of operation is still the same.

For example, laboratory ovens are common in R&D institutions. These may include, universities, industry laboratories or research institutions.

A laboratory oven. Image source – Wikimedia

A number of laboratory ovens are small in size.

On the other hand, industrial ovens are enormous and features advanced technology. They can perform a wide range of tasks in pharmaceutical industries.

Figure 1Industrial Oven. Image Source: LPG

They come in a wide range of shapes and designs.

Apart from these two, another distinguishing aspect is the nature of the application of the ovens.

Of course, this can apply to both the laboratory and industrial ovens. That is, you may use an oven for:

• Drying applications

An oven with the capability to dry material, should have a maximum temperature of 500°F for electric units and 194°F for steam.

• Depyrogenation and sterilization applications

These are special types of ovens that should reach a maximum temperature of 536°F. In most cases, manufacturers may opt for custom designs.

Customizing pharmaceutical ovens may involve tweaking design, technology, drying capability, cycle time, temperature requirements, etc.

As you can see, the temperature range is a crucial aspect whenever you’re buying an oven.

What I want you understand is that, these are general purpose pharma ovens. However, these are those designed for specific applications.

Special Purpose Ovens

These ovens include:

• Vacuum oven

Vacuum ovens are suitable for batch processing. Normally, you can use these ovens to process metallic medical equipment.

Unlike other ovens, here, there are no gases in the oven chamber. This makes it a perfect choice for heat treatment, brazing, case hardening, etc.

• Reach-in oven

A number of laboratory ovens are reach-in ovens. Unlike the vacuum oven, here, a uniform heating across all shelves is due to the horizontal airflow.

It is suitable for drying applications that require over 100 air exchanges per hour. Of course, you can use it for average drying applications in pharmaceutical industries and industries.

• Clean process ovens

In these ovens, the temperatures exceed 260° C. They are common in medical equipment manufacturing industries.

• Burn-in ovens

These are special ovens for producing electronic components. Normally, the oven can attain an average temperature of 260° C with the circulating air being nitrogen in most cases.

For the scope of this article, I will focus on pharmaceutical oven for general applications.

As I stated earlier, you may classify oven depending on their designs, features and structure. However, you can’t do this if you don’t know the various parts of the pharmaceutical ovens.

I will explore this shortly.

#2: Basic Parts of Pharma Ovens

An oven is an assembly of different components that perform a range of functions. The number of parts will depend on the complexity of design and technology.

It doesn’t matter whether it is a laboratory oven or an animal & pharmaceutical industrial oven.

Below is an image showing the basic parts of pharma ovens:

Parts of laboratory oven. Image source – GlobalSpec

Now, let’s discuss some of the most critical parts of a pharmaceutical oven:

· Heat source

To dry the content of the oven, you need a source of heat. Depending on the design of your pharma oven, the sources of heat may include electricity, infrared heat or vapor.

The degree of heat depends on the type of heating elements. That is, with vapor, your oven can attain between 50 – 240°C and infrared heat 50 – 340°C.

· Automatic control systems

Drying materials in an oven involve many processes that you should precisely control to achieve the desired result. In most cases, hot air circulation ovens are equipped with computer control systems.

With these, you can precisely control the heating temperature. This effectively dries the content of the oven without altering its intrinsic properties.

Use the control panel to adjust the batch oven temperature for optimal drying process. The main aim here is to reduce the temperature difference between the bottom and top section of the oven.

From the control unit, you can control many parameters such as temperature, set timer and control blower, alongside other functionalities.

· Pharma oven trays

This is where you place all the materials for drying. A pharmaceutical oven may have one or more trays depending on its design and structure.

· An axial flow blower

The heating element is not in the oven chamber. It is the axial flow blower that pushes hot air into the oven chamber.

As this warm air blows through the oven trays, it displaces the cold air. This is a continuous process that causes the drying effect of the ovens.

An axial flow blower could be a 3 blade centrifugal fan you can see in the image above.

· Inlet and outlet

The hot air enters the oven chamber via inlet and exits through the outlet. This process continuously drains the moisture in the material.

· Electric motor/driving mechanisms

It is this electric motor that rotates the fan/blower to circulate air within the heating chamber. Depending on whether you opt for standard or custom pharmaceutical oven, it may have one or more driving mechanisms.

· Alarm system

Pharma ovens have audible and LED alarm systems. They are automatically activated whenever an oven reaches certain operating conditions.

· Safety accessories

The auto shut-off and over temperature protection device protects the chamber oven from overheating. This will ensure the specimen in the oven is not affected by the excess heat.

· Insulation mechanism

An insulator prevents the loss of heat by conduction from the oven chamber to the external environment. A reason why the external surface of the oven will remain cool despite the heat being circulated within the chamber.

· A lockable door

Pharmaceutical ovens are made from food grade stainless steel. They have lockable doors through which, you can place or remove the oven content.

Basically, these are the most basic parts of a pharma oven. Always remember, an oven may have even more features and parts depending on its complexity and design.

Remember, all these components are fully enclosed and you may not see them without dismantling the oven. Ideally, this is what you will see:

A fully assembled pharma oven. Image source – Labpinions

Now, with all these in mind, let’s explore the working principle of a pharmaceutical oven.

#3: The Working Principle of a Hot Air Circulation Oven

Basically, how a pharmaceutical oven work can be summarized using the image below:

An image showing how hot air is blown by the fan to the oven chamber. As you can see, the air is being recycled, thereby saving on heating costs

An animal & pharmaceutical industrial oven design is such that, air is drawn from the operating room to effectively dry the products within the oven chamber. The process is such that it does not alter the intrinsic properties of materials.

How a pharma oven work is based on convection. As you can see from the above designs, the heating and oven (where you place material) chambers are completely isolated.

Therefore, there are no instances of radiant heat reaching the surface of the material you intend to dry in the oven.

The process is this simple:

1. Place the material you would like to dry, cure or bake in the oven chamber.
2. From the control panel, enter all parameters depending on the properties of the material.

• Switch on the pharma oven.

1. With the oven on, the source of heat will begin to warm the air within the heating chamber.
2. At the same time, the air blower activates (begins to rotate). It begins to blow air into the oven chamber.
3. As the blower directs the warm air into the oven chamber, it displaces the cold air. This directs the cold air to the heating chamber.

• This process continues until the entire chamber is warm
• During the process, air moves both over and under the oven trays causing uniform drying. It ensures the temperature is distributed evenly within the oven.

1. Depending on the nature of the process, you can adjust the intake and exhaust sections of the oven. As a result, it can either withhold or release humidity, while expelling VOCs and fumes.
2. As the process continues, the oven automatically, maintains the appropriate relative humidity.

To reduce the cost of operating a pharmaceutical oven, the insulators prevent the loss of heat via conduction. Moreover, the system itself recycles hot air and uses the function of enforcing ventilation.

Knowing how a pharmaceutical oven work is crucial, however, this information may not be enough. You need to focus on important features that will ensure your oven functions optimally at all times.

#4: Important Features of Pharma Ovens

These are the key aspects that will determine the efficiency of any drying process. So, whenever you’re planning to buy a batch oven; it is important that you consider an oven with the following key features:

• Advanced safety mechanism such as auto shut-off, alarms, over temperature protection etc.
• An easy to use interface
• High level of drying accuracy, precision and consistency
• Data logging capability/process parameter recorder, more so for those in laboratories.
• Precise temperature monitoring capability
• A wide range of heating temperature
• Efficient heating mechanism
• Energy efficient electric motor
• A stainless steel structure and FDA approved gaskets
• Automated system with a programmable control system (if possible)
• Principle of regulating temperature
• Ease to clean and maintain the oven

Remember, all these factors will determine the efficiency and reliability of a pharmaceutical oven.

Closely related to this, another crucial aspect of pharmaceutical ovens you need to know is:

#5: The Standard Specifications of Pharmaceutical Ovens

Ability to specify the type of pharmaceutical oven is crucial when shopping for a new equipment. Normally, you can get all this information from the technical manual or product brochure.

The standard specification of the machine may vary depending on both design and structure. Below is an example:

Technical specification of pharma ovens

In short, here are the key aspects you should consider:

• Tray capacity
• Working temperature range
• Design and type of blowers
• Electric heater rating
• Blower driving unit rating
• Number of racks and trays
• Size of the trays based on width, length and height

Another critical aspect when shopping for a quality equipment is the quality compliance.

#6: Quality Compliance and Requirement for a Pharma Oven

There are certain quality requirements and standards for all pharma ovens. This is to ensure consistency, optimal performance, safety and reliability of the entire equipment.

These standards highlight the:

• Approved materials for contact parts; mainly stainless steel.
• All electrical and heating sections such as electrical heating system
• Right standards for the control systems
• Approved material for the gasket parts

In short, what do I mean by all these?

Whether you need a custom pharmaceutical oven or standard oven design, they should be CE, CGMP, BS 2648, and so on.

#7: Practical Applications of Hot Air Circulation Oven

Laboratory oven or pharmaceutical industry drying ovens are suitable for a wide range of applications such as pharmaceutical, chemical, herbal and nutriceutical industries, just to mention a few.

In all these industries, the hot air circulation ovens play a fundamental role in:

• Sample testing
• Solvent or water removal
• Backing
• Evaporation
• Sterilization, annealing and curing (when manufacturing pharmaceutical equipment)

These are some of the most common applications of pharmaceutical ovens.

Whenever you choose a high quality hot air circulation oven, there is a high chance that you will enjoy many benefits. I have highlighted some in this article earlier.

Still, to make it easier for you to understand I will have a quick overview of these benefits.

#8: Key Benefits of Pharmaceutical Ovens

Whenever you buy quality chamber ovens, you will enjoy the following key benefits:

1. Achieve a uniform and effective drying easily
2. It is a versatile machine that processes a range of products

• Accuracy and precision guarantees a reproducible process

1. Low maintenance costs
2. Reliable and durable
3. Made from the FDA approved materials, hence safe and hygienic

• Modular design, thus easy to assemble and disassemble
• Structure made from stainless steel, making it easy to clean

1. Superior performance due to uniform hot air distribution
2. cGMP compliant

Conclusion

In short, whenever you’re planning to buy a pharmaceutical oven, it is important to consider all these 8 factors. With these, I am sure you will get the right equipment for your unique drying applications.

At times, analyzing all these factors may prove cumbersome, especially if you’re new to pharma ovens.

In such situations, don’t hesitate to contact us.