Temperature Profiling: The Process and The Underlying Benefits

What is Temperature Profiling?

Temperature profiling is a process used to record the temperature of heat-sensitive equipment, instruments, or products during the entire thermal cycle. Temperature data can be recorded continuously or after a fixed interval and then fed to centralized storage for further access and analysis.

 

Figure 1. Temperature profiling is an important tool in determining the status of heat distribution in process equipment. Image used courtesy of Adobe Stock

 

Temperature profile studies provide insight into temperature control and distribution. It allows the person to analyze how equipment temperature varies throughout the control process.

For example, temperature profiling can be used to visualize what temperature existed at a specific time and how the product reacted to this temperature.

During temperature profiling, the temperature is recorded for all critical locations in equipment that can affect the heating process.

As an example using standard equipment, the temperature is recorded at various control probes near doors, product placement, blower, and drain, and is then used by the main controller to adjust the temperature as needed.

 

Components of Temperature Profiling Systems

An entire temperature profiling system extends from the sensors at the machine level up to the processing software.

 

Temperature Sensors

Temperature sensors are used to collect the temperature information of a particular location. They convert the physical temperature value into appropriate electrical/electronic or resistance format, readable by the data loggers.

 

Figure 2. One temperature sensor is also placed near the control temperature probe, to analyze equipment’s temperature control behavior. Image used courtesy of Adobe Stock

 

For accurate temperature monitoring, it is necessary to place sensors at precise locations and must not touch any hot surface. Otherwise, they will collect erratic temperature data.

Commonly, two types of temperature sensors are used in temperature profiling systems: thermocouples and RTDs. Thermocouples have a higher measuring range but have the least accuracy. RTDs accurately determine the temperature values but are limited by measuring range.

 

Data Loggers

Data loggers are electronic devices that record and store various process values, including temperature. It records changes in temperature over a specified time and provides useful information such as high and low-temperature values. Temperature sensors are directly connected to the data loggers to transfer the temperature information to them.

Data loggers, having their battery, internal memory, communication media and Input/output ports, work independently of computing devices. The data collected by data loggers are retrieved and transferred to a computer system, where a software system is used to analyze the retrieved data.

 

Figure 3. A data logger can record temperature values over time. These data values can be retrieved through a computer system for record and analysis. Image used courtesy of Supco

 

Thermal Buffer

Thermal buffers are protective materials, typically attached to data loggers. They protect the data loggers from the area’s harsh environment due to process conditions. Because the environmental temperature around the equipment can be high, it can affect the ability of the data logger to display the actual temperature due to the sensitivity of internal electronic components.

 

Software System

The software system analyses the collected data and converts it into useful information. It can also detect and identify fault points with the help of the temperature data collected.

Typically, the software is supplied with the data logger and can generate different temperature-versus-time data versions such as tabular, chart, and graphical forms. These data formats can be easily selected from the options available in a software system.

The above data forms can be archived and made part of the record. The records can be electronically saved in the computer memory, and it is also possible to make hard copies.

 

Examples of Processes Using Temperature Profiling

Overviews can be useful, but what are some examples of actual temperature profiling in process industries?

 

Heat Treating of Metal Parts in a Furnace

A high-temperature furnace treats metal parts, such as bearings and hand tools, to increase their strength and usability. The furnace’s temperature is automatically controlled through the centralized control system. Temperature profiling is performed to ensure accurate temperature distribution and control throughout the furnace, to prevent over and underheating of metal parts.

For temperature profiling, thermocouple sensors are used since the average temperature of the furnace is around 1000°C, and thermocouples can satisfactorily record in these ranges. The thermocouple is connected to a data logger that records the furnace temperature and transfers it to the computer system. The thermal barrier to the data logger protects it from the high temperature of the furnace. Software installed on the computer can be used to analyze the temperature distribution and to generate reports.

 

Pharmaceutical Validation

Among other tests in pharmaceutical validation activities are the temperature profiling of autoclaves and dry heat sterilizers. These two pieces of equipment sterilize various pharma manufacturing components like ampoules, glass jars, and even some pharma products at high temperatures.

During validation, temperature profiling guarantees uniform temperature distribution throughout the sterilizer chamber and ensures the correct functioning of temperature control function. It also helps to detect any air pockets inside the chamber that resists temperature during sterilization.

 

Advantages of Temperature Profiling

There are a number of advantages to the temperature profiling process.

 

Enhance Product Quality

The quality of a product in temperature control equipment directly depends on the accurate temperature. If the temperature remains over or under the set point, it can severely affect the final product.

Temperature profiling acts as a safety system to the equipment’s temperature control system, which protects the final product from the adverse effects of over or under-temperature.

 

Identifying Failures

Temperature profiling effectively detects and identifies problems within temperature-sensitive equipment and the environment. If the data logger shows a significant difference between its logged and equipment temperature values, it indicates a potential problem with the equipment’s temperature control system.

Temperature profiling also helps to detect problems between the equipment’s temperature sensor and any associated wiring or main controller. Sometimes, a minor adjustment or calibration can compensate for the difference.

Additionally, the placement of objects or items inside the chamber can cause temperature differences. This problem can be solved by re-arranging the objects inside and then re-analyzing the results of temperature profiling.

 

Figure 4. An autoclave uses a high-temperature process for sterilization in healthcare and laboratory settings. Image used courtesy of Adobe Stock

 

Regulatory/Standardization Requirement Compliance

Regulatory and standardization bodies of certain industries, such as the pharmaceutical, require their manufacturers to perform temperature profiling of controlled areas and equipment. Otherwise, manufacturers may face warning or even shutting down manufacturing operations.

For example, United States Pharmacopeia - USP 1079 – Good Storage and Shipping Practices, guides pharma manufacturers for temperature profiling of warehouses to detect temperature variation in different parts.

 

Minimizing Energy Waste

Temperature profiling helps minimize energy wastage by reducing the temperature swing of a production process. It minimizes unnecessary energy consumption, such as electricity and steam utilized for generating extreme temperatures.

 

Temperature Profiling in Industry

Temperature control processes and equipment are essential components of almost every process industry, affecting the final product's quality. Equipment manufacturers pay special attention to temperature control features with an inbuilt temperature safety system. However, these systems can fail, and it is also possible that this failure can go unnoticed.

Temperature profiling is an effective process for identifying and detecting problems related to temperature control systems. It helps personnel devise more effective temperature control functions by focusing on automation systems and equipment design.