DOP Test (HEPA Filter Leakage)

Dispersed oil particulate (DOP) testing, also known as filter integrity testing, is a process in which the integrity of HEPA (high efficiency particulate air) or ULPA (ultra-low penetration air) filters is challenged by adding particles and measuring the output. In this process, oil is dispersed as an aerosol into the upstream flow of the filter media, while the number of particles downstream is measured using a calibrated photometer.

High-efficiency particulate air (HEPA) filters are effective devices used to help provide clean air and reliable ventilation in clean rooms, in vitro fertilization laboratories, and healthcare settings. These are an important part of any ventilation system.

HEPA filters are tested throughout production and must pass stringent commissioning tests before being released into the market. Their role is crucial and it is important that they work as intended.

However once they are installed and used extensively the filter needs to be tested to ensure it still performs to the required standard. These tests need to be done every 6 months to make sure they are in top condition. Diffused oil particle (DOP) testing is an essential part of this and is used to verify that HEPA filters provide purified air.

These filters are mechanical parts and like all other mechanical parts, they are prone to malfunctions and failure. Ventilation systems must be maintained and serviced when used in special environments. The job of HEPA filters in these systems is to remove dust, pathogens, and other small microorganisms from the air and provide clean, bacteria-free air instead.

There is no room for compromise, especially in healthcare settings. If a HEPA filter performs as much as 1 percent below expected standards, it could have significant consequences down the road. Strict regulation ensures that the ventilation system consistently performs to the expected standard. If it fails any performance tests, defective parts must be replaced. This is where DOP testing comes into play. DOP testing is an important part of the maintenance and verification of these controlled environments and quickly detects malfunctions in the HEPA filter and ventilation system. This test verifies whether the device meets the required standards.

The DOP test involves the oil particle arriving in aerosol form. A high concentration of particles is released into the airflow of the test area (upstream of the filter). Measurements are then taken with a calibrated photometer to determine whether the particle has passed through the filter or downstream of the housing. This simple process stresses the seals, housing, ports, filter and frame of the HEPA mechanism and quickly detects any leaks.

DOP testing follows a strict procedure and is therefore only carried out by professional testing teams. First of all, the testing team must follow a strict and compliant procedure to ensure that filters are tested reliably. After a detailed examination, the appropriate injection point must be determined and the injection mechanism must be designed. The ventilation system needs to be isolated from all power sources and pumps may need to be installed to provide adequate pressure absorption. Their activities are then synchronized to ensure that accurate readings are recorded by the photometer. Depending on the results, the aerosol concentration may need to be increased or decreased during the test.

In addition to testing the condition of your ventilation system, the DOP test can also determine whether all of the air is passing through the filter. Professional teams monitor dead spots with limited activity where dangerous contaminations can accumulate.

In the past, dic-octyl phthalate was used as the oil in DOP tests, but due to increasing concerns about its carcinogenic properties, poly alpha olefin, a non-carcinogenic liquid, is preferred today. Other liquids used include paraffin oil.

Among the numerous testing, measurement, analysis and evaluation studies it provides for businesses in various sectors, our organization also provides testing services in accordance with the "ASHRAE Standard 62.1 Ventilation and acceptable indoor air quality" standard, with a trained and expert staff and advanced technological equipment.