HEPA filter what is a High-Efficiency Particulate Air (HEPA) filter, ULPA filters? How HEPA filters work,  its efficacy test and test for integrity, and Penetration, Most Penetrating Particle Size (MPPS),  and standards for a HEPA filter. What DOP test ? What is PAO test.
What is pleted HEPA filter and Minipleted HEPA filter ? 
HEPA filter a type of filter which has high efficiency to filter out about 99.997% that is why they are termed as High efficiency particulate air filter,HEPA filters are made up of a mesh of fiber glass fibers of thickness ranging from 0.5 to 2 micrometer and are closely packed with each other with as low clearance as 0.3μm which may be bit greater.

How HEPA filters work.
Particles in air are trapped in to HEPA filter fibers when air caring these particles is blown or passed through these fibers, by mechanism of interception (particles adhere to fibers), impaction (particles embed in to the gap) and diffusion and then blocking, particles with lower particle size than the gap between these fibers are also trapped as the result above mechanisms fiber diameter, filter thickness, and face velocity are the factors which affect the efficacy of the HEPA filter.

Importance of HEPA filter in pharmaceutical industry very great, HEPA filters are used in industry where ever it is require to make the environment free of particulate matter as well as free from microbial contaminants (bacterial ,viruses etc) in clean rooms
A HEPA Filter of efficiency of 99.97% is usually used in aseptic manufacturing filing and packing, parentral dosage manufacturing.These filters are mounted in Laminar Air Flow Bench which are then used as clean area for actual aseptic manipulations or aseptic filling where usually a clean aria of class 100 are required, such laminar air flow bench are typically found within a clean aria of class 1000, which again are maintained by HEPA filters installed in a HVAC system.

For High Efficiency Particulate Air filter , A velocity of 0.45 meters/second (90 feet per minute) has generally been established, with a range of plus or minus 20 percent around the setpoint. Higher velocities may be appropriate in operations generating high levels of particulates.

High-Efficiency Particulate Air (HEPA) efficacy test and test for integrity.
There is a major difference between filter leak testing and efficiency testing. An efficiency test is a general test used to determine the rating of the filter. An intact HEPA filter should be capable of retaining at least 99.997 percent of particulates greater than 0.3 nm in diameter. The filters maximum resistance to airflow, or pressure drop, at its nominal flow rate is usually specified around 300 Pa.

Ultra low particulate air filter.(ULPA filter)
The ulpa filter is similar to that of HEPA Filter with respect to its principal of operation and material of construction ,except that the fiber diameter is lesser so as to produce high level of air filtration efficiency.
An ULPA filter (theoretically) is capable of removing about 99.999% particles from upstream air it is very effective filter , and airborne particles of size 120 nanometres above are removed efficiently to an level of 99.999% hence standard ULPA Filter are said to have an efficiency of 99.9995% at .12 micrometers.

Leak test of HEPA filter
High-Efficiency Particulate Air (HEPA) filter integrity should be maintained to ensure aseptic conditions. Leak testing should be performed at installation to detect integrity breaches around the sealing gaskets, through the frames, or through various points on the filter media. Thereafter, leak tests should be performed at suitable time intervals for HEPA filters in the aseptic processing facility. For example, such testing should be performed twice a year for the aseptic processing room. Additional testing may be appropriate when air quality is found to be unacceptable, facility renovations might be the cause of disturbances to ceiling or wall structures, or as part of an investigation into a media fill or drug product sterility failure. Among the filters that should be leak tested are those installed in dry heat depyrogenation tunnels and ovens commonly used to depyrogenate glass vials. Where justified, alternate methods can be used to test HEPA filters in the hot zones of these tunnels and ovens.
A Procedure is required to set for a pharmaceutical manufacturing unit to conduct HEPA filter leak test every 6 months.
Any aerosol used for challenging a HEPA filter should meet specifications for critical physicochemical attributes such as viscosity. Dioctylphthalate (DOP) and poly-alpha-olefin (PAO) are examples of appropriate leak testing aerosols. Some aerosols are problematic because they pose the risk of microbial contamination of the environment being tested. Accordingly, the evaluation of any alternative aerosol involves ensuring it does not promote microbial growth.Dioctyl Pthalate Arosol is not safe in case it is in healed by human, it is carcinogenic.Therefore Poly Alpha olefin aerosol is preferred in Pharmaceutical Industry.

Scanin of HEPA filter during leak test  and HEPA filter efficiency test
The purpose of performing regularly scheduled leak tests, on the other hand, is to detect leaks from the filter media, filter frame, or seal. The challenge involves use of a polydispersed aerosol usually composed of particles with a light-scattering mean droplet diameter in the submicron size range, including a sufficient number of particles at approximately 0.3 nm. Performing a leak test without introducing a sufficient upstream challenge of particles of known size upstream of the filter is ineffective for detecting leaks. It is important to introduce an aerosol upstream of the filter in a concentration that is appropriate for the accuracy of the aerosol photometer. The leak test should be done in place, and the filter face scanned on the downstream side with an appropriate photometer probe, at a sampling rate of at least one cubic foot per minute. The downstream leakage measured by the probe should then be calculated as a percent of the upstream challenge. An appropriate scan should be conducted on the entire filter face and frame, at a position about one to two inches from the face of the filter. This comprehensive scanning of HEPA filters should be fully documented.

A single probe reading equivalent to 0.01 percent of the upstream challenge would be considered as indicative of a significant leak and calls for replacement of the HEPA filter or, when appropriate, repair in a limited area. A subsequent confirmatory retest should be performed in the area of any repair.
HEPA filter leak testing alone is insufficient to monitor filter performance. It is important to conduct periodic monitoring of filter attributes such as uniformity of velocity across the filter (and relative to adjacent filters). Variations in velocity can cause turbulence that increases the possibility of contamination. Velocities of unidirectional air should be measured 6 inches from the filter face and at a defined distance proximal to the work surface for HEPA filters in the critical area. Velocity monitoring at suitable intervals can provide useful data on the critical area in which aseptic processing is performed. The measurements should correlate to the velocity range established at the time of in situ air pattern analysis studies. HEPA filters should be replaced when nonuniformity of air velocity across an area of the filter is detected or airflow patterns may be adversely affected.
Although contractors often provide these services, drug manufacturers are responsible for ensuring that equipment specifications, test methods, and acceptance criteria are defined, and that these essential certification activities are conducted satisfactorily.

Chemicals used in integrity testing of HEPA filters?
Dioctyl phthalate aerosols which is , Di (2-ethylhexyl) phthalate, di-sec octyl phthalate, DOP, or DEHP, is most commonly used used in the test for integrity of high efficiency particulate air (HEPA) filters as there are potential health effects associated with its use on the people working with DOP test aerosols which has led to a find a newer and a safer equivalent material to replace DOP.
The next material of choice is a polyalphaolefin (POA) in the 4 centistoke (4 cSt) viscosity grade called as Emery 3004 (POA) which can replace DOP in HEPA integrity testing.

What is meant terms Efficiency, Penetration,Most Penetrating Particle Size (MPPS), for a HEPA filter

Penetration :
Penetration is the ratio of the particle count downstream of the filter to the particle count upstream.

Efficiency of a HEPA filter:
Efficiency is the ratio of the number of particles retained by the filter to the number of the particles used to challenge the filter.

Most Penetrating Particle Size (MPPS): It is a characteristic of a given filter at with this particle size filter has minimum efficacy.
Classification of HEPA filters EU norms EN 1822-1 by their retention at MPPS
H10 > 85 % (Total Retention)
H11 > 80%(Total Retention)
H12 > 99.5 % (Total Retention)
H13 >99.95 (Total Retention)
H14 >99.995% (Total Retention)

HEPA filters standards.
ISO 14644 (1-9), introduced in 2000 most of European countries follow these standards
US FED STD-209E, 1992 USA.
JACA (Japan )
AS1386 (Australia)

How to clean a HEPA filter Cleaning of HEPA filter.

Decontamination of HEPA filters:
It is important to decontaminate HEPA filter when it is used in a clean room which handles vaccines , or a viruses ,bacteria.
HEPA must be decontaminated once it off line , it is decontaminated along with housing filters.
Decontamination procedure and chemicals are required to be chosen after consideration of microbial load and their resistance factors; validation of  the entire process must be done. Integrity of a HEPA filter should be verified when it is being replaced. Person carrying out the activity of decontamination of HEPA filter should be trained and provided a protective or a breathing apparatus so as to protect him from harmful affect of decontaminating chemicals like H2O2 fumes. When HEPA filters are required to be disposed, they must be incinerated before disposal so as to avoid contamination of surrounding.

Do you know now this website has become a most popular and most referred website in pharmaceutical industry and pharmaceutical companies and pharmaceutical manufacturers from all over the world ,for almost all topics related to Pharmaceutical Manufacturing , Pharmaceutical Regulatory Affairs and Good Manufacturing Practice for Pharmaceutical Manufacturing (c GMP guidelines ) and latest news and new drugs developments.

You may also like following articles

What is 21 CFR Part 11, US FDA guidelines requirements of FDA compliance and CFR 21 Part 11.

What is a Site Master file of a pharmaceutical company

What is Generic Drug

What is Reference Listed Drug  ? ( RLD )

What is Pharmaceutical Equivalents

What is Pharmaceutical Alternatives

What is Therapeutic Equivalents

What are Post Market studies

Why a drug is bound to protein, What is protein binding?  What is drug absorption , distribution ?

Do Physical properties contribute to drug activity.

What is drug receptor , How a drug resistance occurs

Mechanism of drug resistance

What is drug interaction

Drug interaction, and its examples

What is first pass metabolism of a drug

What is What is 510(k) Clearances ?

What is 510(k) Clearances,

Premarket Notification for medical devices – PMN or 510(k)

What is a drug interaction

Examples of drug interactions

Antibiotic Definition and classification

Antibiotic Resistance and Antibiotic resistance mechanism

Antioxidants food supplements

Vitamin D Details on FDA cautions on accurate dosage of Vitamin D

What is an antibody? what is monoclonal and polyclonal antibodies?

Terminologies In vaccine Production

Multi stage testing of Virus vaccine production

Testing of vaccines at different stages of production


Enzyme linked immunosorbent assay ELISA

Raido Immuno assay


Pharmaceutical Aseptic Manufacturing Process Terms , Terminology and Definitions.


Here are some articles which will be useful for you in further understanding of aspects of sterile dosage form manufacturing and regulatory affairs and good manufacturing practice in

pharmaceutical industry

Pharmaceutical Validation

Types of validations in pharmaceutical manufacturing

Requirements of documents for validation of sterilisation process

How to investigate OOS out of specification results

Determination of Phenol coefficient of a disinfectant

Sterility testing

Clean Room Classification

Time limitations in sterile pharmaceuticals processing

Aspects of validation of manufacturing process in sterile pharmaceuticals

Clinical Trials

Requirements of US FDA Inspections of Clinical Investigators of Clinical Trials




Controlling Pyrogens in injectable dosage forms

Media fill run process simulation aspects Validation of Aseptic Process and Sterilisation

New Drug Application (NDA) how to make a New Drug Application (NDA) to US FDA

Abbreviated New Drug Application (ANDA) What is ANDA , detailed information about ANDA preparation and submission to US FDA

How to make Investigational New Drug (IND) Application to US FDA

Drug applications submission to us fda Over the counter Drugs OTC drugs


Electronic record in pharmaceutical manufacturing industry

Good manufacturing practice in pharmaceutical industry

Pharmaceutical industry pharmaceutical companies and FDA latest updates

Here is an interesting article on world wide pharmaceutical industry and making a carrier in one of pharmaceutical companies article on Pharmaceutical Industry pharmaceutical industry

Find a Job in Pharmaceutical Company –>JOBS IN PHARMA INDUSTRY<—
To Find Pharmaceutical jobs and make a Pharmaceutical careers see here pharmaceutical companies
Here are some interesting articles on Quality assurance systems for pharmaceutical company

Quality assurance in pharma industry

Quality by design concept for pharmaceutical industry

Quality by design concept in pharmaceutical industryan explanation

Useful Books For Pharmaceutical Manufacturers and Pharmaceutical Professionals

%d bloggers like this: