Types of packaging integrity testers

Introduction

There are various types of packaging integrity testers for checking the integrity of the packaging. The selection of different types depends on the product and packaging being used. Each type has a separate application and cannot be interchanged from other types.

For optimum and reliable results, it is necessary for the concerned personnel and operators to know various types of packaging integrity testers. Otherwise, it will result in the wrong selection of integrity tester and affect the integrity of the packaging.

How do select different integrity testing methods

As discussed above, there are different types of packaging integrity testers. For accurate results, it is necessary to study the requirements and select the packaging integrity tester. 

Below are some criteria that can help select the correct packaging integrity tester.

Inline vs. Offline

Inline integrity testers check the integrity of packaging during production without taking the sample away from the machine in the laboratory or test bench. The test is performed in the running condition of the machine without stopping or halting the production process. Inline testers are integrated with the production machine. The production machine's main controller continuously monitors these testers' output. A mechanical assembly separates the defective packaging from the correct packaging by taking command from the main controller of the machine.

Offline testers check the packaging integrity away from the machine. The machine is stopped from taking samples until results are obtained. The test is often performed in the laboratory or on a separate test bench. When the trial is concluded, the result is communicated to the concerned personnel for further processing. 

Primary Packaging Type

The packaging material that comes in direct contact with the product is called primary packaging material. Integrity testing for each primary packaging is different and follows a different technique and methodology. For example, the integrity tester for a blister pack cannot be the same as that of ampoules.

Filled Container or empty Container

Integrity tester also depends on whether the Container being tested is empty or contains a product. Some test methods are not suitable for empty containers, as they damage the Container and cannot be used for the product. Similarly, some test methods are not suitable for filled containers, as it affects the test output.

Product Type

Packaging integrity testing also depends on the product being used in packaging material. Different test techniques behave differently on different products. Packaging integrity testing can output inconsistent results if the appropriate product type is not correctly selected. 

In some cases, a particular test method is not suitable for liquid products, while others are not suitable for the solid dosage form. They produce unreliable and erratic results when the appropriate product type is not considered.

Destructive Vs. Non-destructive test 

Packaging integrity testers can be divided into destructive and non-destructive. They are classified according to the usability of the packaging after performing integrity testing.

Destructive Testing

Destructive testing refers to the destruction of packaging, and the product inside it requires re-packing before marketing or reaching its intended user. The product remains safe and can be used for consumption by its end user. 

In Destructive testing, the test mechanism penetrates the packaging material or is performed by immersing the packaging into the sole liquid. This method destroys the packaging, and the product is exposed. The product requires re-packing before it reaches its intended user.

Non - Destructive Testing

In non - destructive testing, the packaging is not destroyed and remains intact with the product. In this test, the product does not require re-packing and can be marketed to use by the intended user without any additional packing or processes.

Non-destructive testers are the latest and use automation techniques to perform the test. These integrity testers are also costlier than the destructive type, with higher operating costs. 

Integrity testers technologies

Let’s discuss some common technologies of packaging integrity testers

Vacuum Decay

This test is the non-destructive type and is used to detect leaks in pharma packaging. It applies vacuum in a product-containing container. A leak in packaging affects the vacuum levels, which are used to detect the presence of a leak.

This instrument consists of a small enclosure in which the packaging is placed. A vacuum can be applied to this enclosure, and the associated sensor measures the vacuum levels.

To check the integrity of the packaging, a vacuum is applied to the enclosure with the package in place. The enclosure is made airtight, and the vacuum value is monitored. A small leak or hole in the packaging will affect the vacuum value, and it will become impossible to reach the desired vacuum value, or its values will decrease during the pre-determined time. 

This test is best suited for non-porous, flexible, and rigid packaging. 

HVLDmc

Microcurrent High Voltage Leak Detection is a variant of HVLD that utilizes a small amount of current to detect leaks across the packaging. It can detect leaks and holes in vials, syringes, and liquid-filled parenteral products. 

HVLDmc is a non-destructive type that uses the principle of electrical conductivity. A leak causes to change in the value of conductivity and is similarly identified as a leak in the packaging.

It consists of two electrodes – Inspection and detection. A container is placed between these electrodes, and voltage is applied—a current passes between the inspection and detection electrodes. The value of current is different for both correct and defective packaging. 

Helium Leak Detection

The Helium Leak Detection method uses helium gas as a tracer to detect leaks. The amount of helium gas leaked is directly proportional to the leakage. This method is used for blister packs, pouches, and pre-filled syringes. 

In this test, helium gas is filled in the packaging and placed in a vacuum enclosure. The air is evacuated to create a vacuum in the chamber. If there is a package leak, helium will flow from the packaging. The helium flow is detected and measured and directly proportional to the leak and volume.

With this test, quantitative results are also possible. For this purpose, the quantity of helium gas in the packaging must be known, which is then used to compare with the escaped volume.

Airborne Ultrasound

Airborne Ultrasound is a non-destructive method used to check the integrity of the seal in a pouch packing. Chances are, for a properly sealed pouch, air or any other gas might pass through the seal. 

Traditional methods use destructive methods such as peel strength or burst methods to check the leak in the seal. However, in some cases, seal tightness cannot be accurately determined. The Airborne Ultrasound method is used to overcome the traditional test's shortcomings.

The Airborne Ultrasound method uses ultrasound waves to detect leaks in the packaging. Ultrasound waves propagate through the packaging, and the returned waves are analyzed for a leak. The seal to be tested is placed in line with the ultrasound sensors. The value of the received signal is directly proportional to seal quality and helps depict the inside condition of a seal. 

Airborne Ultrasound method can be used for any material and its result is not affected by specific material characteristics such as color, print, surface finish and porosity.

Pressure Decay

A pressure decay test is used to check the integrity of an empty container. This test is performed before filling the pharma product to check its integrity.

The Vacuum test method is unsuitable for empty containers, as empty containers often collapse under vacuum conditions. Pressure decay methods can be effectively used for empty containers, as these types do not pose any danger to the empty chamber.

In the pressure decay type, a gas is filled into the container. The quantity of gas is controlled, typically in the range of 50mbar. After pressurizing, the container is monitored for gas value by a pressure-sensing device for a specified time period.

If there is a leak in the container, the gas will escape, and its pressure will drop. If there are no leaks, the pressure remains constant, and the container is said to be passed.

Force Decay

Force decay tests are non-destructive types used to check the integrity of blisters and sachets having limited headspace. It measures the force exerted on one side of the packaging against a force sensor. These test types can also check the integrity of the seal for the packaging mentioned above.

It consists of an enclosure in which packaging is contained for testing purposes. There are two plates; one of them is connected to a force transducer. Air in the enclosure is pulled out to create a vacuum. Under vacuum conditions, the package will expand and exert force against both plates until it reaches equilibrium. The sensor measures the force exerted by the packaging on the plate.

Force is measured for the specified time period and checked to see if there is any change in its value. If there is no change and the force value remains the same, the package and its seal are satisfactory.

On the other hand, if the value of force changes, it indicates a poor seal or a hole in the package. As a result, the package is said to fail the test, and production is stopped.

About the Author

Muhammad Asim Niazi has a vast experience of about 11 years in a Pharmaceutical company. During his tenure he worked in their different departments and had been part of many initiatives within the company. He now uses his experience and skill to write interested content for audiences at PharmaSources.com.