High Voltage Leak Detection vs Vacuum Decay: what you should know

To respect quality standards and protect consumer health, pharmaceutical products must be tested to identify any defects in the packaging seal and structural integrity.

The Container Closure Integrity Testing (CCIT) identifies a wide range of packaging defects, rejecting products that do not comply with standards. This gives the manufacturer the certainty that the products being placed in the market have been inspected and that they will withstand storage and transportation. 

International standards describe a variety of tests that can be used for CCIT: the Vacuum Decay Method (VDM) and the High Voltage Leak Detection (HVLD) are commonly used. Both solutions effectively identify products that do not meet standards, but they vary in terms of flexibility and scope of use.

High Voltage Leak Detection and Vacuum Decay: an overview

The Vacuum Decay Method detects pressure changes that can occur when a closed and sealed product is exposed to a vacuum. The products to be checked are placed in test chambers in which a vacuum is applied. Then, pressure values are read twice, a few seconds apart. If the difference between the two pressure values exceeds a threshold established during machine set-up, the container has a leak and must be rejected.

High Voltage Leak Detection detects holes or cracks using electricity to check the integrity of containers made of an insulating material (such as glass) containing products that conduct electricity (such as a drug in a liquid solution). In this test, a potential difference is applied to the container using electrodes, and conductivity variations are measured. If packaging integrity is compromised, the machine will detect a change in conductivity, indicating non-compliance with the expected quality standard.

What are HLVD Strengths and Differences?

The main strength of the High Voltage Leak Detection or HVLD is its ability to detect very small holes while operating at high speeds. However, this technique also has several limitations:

1. First, both the material from which the container is made, and its content influences the test result, since the result depends on the conductivity of the medium. This means that if the packaging is modified significantly, the machine will have to be set up again to guarantee reliable results. In addition to the package material, its shape can also influence how an HVLD test is conducted. In some cases, it is not possible to inspect the entire container in a single step so several tests are needed to check the tightness of different sections of the container, and the entire package cannot always be inspected.
   
   
2. Another of HVLD limitations is that packaging must be made of an insulating material for testing to be able to use this technology. If containers with metal parts (e.g., vials with an aluminium cap) are tested, the metal section cannot be inspected.
   
   The VDM or Vacuum Decay Method technology, on the other hand, can inspect a product completely regardless of its shape, material, content, or presence of electrically conductive parts. This greater process flexibility means that it can be used for products of any shape and made of any non-porous material.
   
   
   • The packaging can contain products of any kind: liquids, solids, powders, freeze-dried products or in a vacuum.
   • The VDM technology can provide reliable seal results for a much wider range of containers than HVLD solutions.
   • Its inspection speed is lower than HVLD, although currently machines with VDM technology can test up to 600 products per minute, as is its sensitivity, the VDM can detect holes measuring 1 micron in laboratory applications, and 5-10 microns in in-line applications.

VDM

HVLD

Why choose the Vacuum Decay Method

Bonfiglioli Engineering has adopted the VDM for its versatility and possibility to create machines tailored to diverse types of packaging containers and their contents.

In its 50-year history of manufacturing and installing leak detection machines, Bonfiglioli Engineering has delivered over 5000 machines with the VDM technology to customers worldwide. This experience allows Bonfiglioli Engineering to offer its customers VDM machines for any application, whether for use in the laboratory or in line, covering a wide range of products and easily adapting to the customer's needs.