Air Filter Selection

Preface

The below guidelines on selecting high efficiency air filters for the pharmaceutical industry mainly deal with filters in the HVAC system (i.e. make-up air and terminal and exhaust filtration). The guide, while general, is a Camfil Farr recommendation based on our experience of supplying filtration systems to the industry.

Camfil Farr's Pharmaseal

There are many different process types in pharmaceutical manufacturing, which place varying demands and concerns on the filtration systems. In contrast, a semiconductor fab has a standard design, while in pharma there are probably no two cleannroom facilities the same, unless they are for the same owner and process.

We are concerned with many issues when we talk about filtration in the pharmaceutical industry:

• global and local standards
• filter economy
• filter efficiency
• filter location
• environmental effects of used filters
• room classification
• filter testing
  

This article focuses on testing and standards.

Testing of filters (both in house & in situ tests)

There are many reasons why filters fail on site. These include poor packing, transport damage, inexperienced personnel handling filters, and - probably most common - wrong selection or specification of filters. This is understandable given the wide range of existing standards and client demands.

Example’s of filter testing protocols:

1. EN 1822 High efficiency air filters (HEPA & ULPA) classification and test of filters.

Eurovent 4/4 (replaced by EN 1822, but still used and misunderstood, especially when specifying efficiency). Eurovent uses NaCl (0.65 micron diameter) whereas EN1822 uses the most penetrating particle size (typically 0.15-0.2 micron diameter). The resulting efficiency can be in the range of 99.997 for 0.65 micron particles and 99.95 for MPPS for the same filter.

Eurovent 4/4 is a volumetric test and may not detect pinhole leaks within the filter, whereas EN1822 involves a full media scan test, and would be the natural choice for pharmaceutical use for the higher grades of HEPA filters.

However, care should be taken when selecting HEPA filters for areas that need to be in situ tested. (i.e. factory scan test and meeting requirements of the in situ scan test, such as the 0.01% penetration requirement).

Other testing protocols include:

2. IEST-RP-CC001.3 HEPA & ULPA Filters (1993)
3. IEST-RP-CC006.2 Testing Cleanrooms (1997)
4. IEST-RP-CC021.1 Testing HEPA & ULPA filter media (1993)
5. IEST-RP-CC034.1 HEPA & ULPA filter leak test (1999)

It is not the purpose of this article to discuss each individual recommendation. However, costly mistakes can be eliminated by discussing each project on a case-by-case basis with the owner, designer, contractor and supplier and pooling the collective knowledge before a detailed specification is written.

Table 1: Standards applicable to the American & European markets

	Classification & Particle Counting in The Room	Filter Classes	Testing Filters
FDA/USA	US FED STD-209 E	IEST-RP-CC001.3	IEST-RP-CC006.2 IEST-RP-CC021.1 IEST-RP-CC034.1
GMP/Europe	ISO-14644	EN-1822	EN-1822

Standards International & National:

Today we are getting closer and closer to a universal standard for clean room classification that meets the requirements of GMP for Europe, the US and Asia. These countries generally follow the aforementioned standards. Many countries in Asia will use their own national standards, such as JACA in Japan and AS1386 in Australia. These standards are generally applied to manufacturers located within the region's borders. However, if an American or European manufacturer invests in Asia and intends to ship products to their home country/continent, they will generally follow their own standards (i.e. GMP, or FDA).

Examples of clean room classification standards:

1. ISO 14644 (1-9), introduced in 2000
2. US FED STD 209D 1998 - FDA’s clean room classification (edition D was replaced by Edition E in 1992)
3. US FED STD-209E, 1992 - FDA’s clean room classification
4. GGMP PIC/EEC Annex 1 (January 1997) clean room classifications

Below is a general comparison of these standards

FED STD-209D	FED STD-209E	ISO 14644-1	GGMP PIC/EEC
1	M 1.5	Class 3
10	M 2.5	Class 4
100	M 3.5	Class 5	A & B
1000	M 4.5	Class 6
10,000	M 5.5	Class 7	C
100,000	M 6l5	Class 8	D

Summary

Selecting high-efficiency filters and accessories (housings, mounting frames, etc.) is not easy. One must consider many parameters including filter efficiency, application, lifespan, running costs, equipment costs and accessibility. Camfil Farr has developed many software programs for optimizing filter selection. This software includes hepa/ulpa selection, clean room design, chemical/carbon selection and LCC (life cycle cost, make-up air). Most of this software is available on request.

With their enormous R&D budgets, pharmaceutical and biotechnology companies play an extremely important role in the future of health care. Filters are and will remain a critical part of the production of their products. Camfil Farr is proud to be the leading supplier of clean air solutions to the pharmaceutical and biotechnology industries. For further information, contact your nearest Camfil Farr sales office or visit our website, www.camfilfarr.com.

Sean O' Reilly
Bio-Pharma Segment Manager
Camfil Farr Group