ULPA filters

Depending on the test method and test result, particle filters are classified as coarse, fine, HEPA, and ULPA filters (Table 9.2). Electrofilters are usually included in the fine filter group. Chemical filters are used for gases. 

HEPA and ULPA filters have been developed. In the CEN EN 1822 1998 test method, the filter s efficiency is determined for the most penetrating particle size (MPPS). Depending on the filter s total level of separation and leakage, the filter is classified as HIO, Hll,.. ., H14 and U15, U16, or U17. HEPA filters are commonly used for inlet air in the pharmaceutical, optical, and food industries. 

IEST-RP-CC034.2 Hepa and ULPA Filter Leak Tests, June 23, 2005. 

Refinement of HEPA filter manufacturing and testing technology and development of the ultra low particulate air (ULPA) filter, have led to an increase of absolute filtration retention efficiency of greater than two orders of magnitude above 99.97%. HEPA filtration efficiencies range from a minimum of 99.97 to 99.99%, with ULPA efficiencies above 99.9999%o for particulates larger and smaller than 0.3 pm in diameter... 

IES (Institute of Environmental Sciences). 1992 IES-RP-CC007.1 Testing ULPA Filters (Recommended Practice). Mount Prospect, II. 

A pharmaceutical company requires a ventilation system to purify the air of a biohazard containment laboratory. HEPA, ULPA, and SULPA technologies were considered but the ULPA filters were deemed sufficient for the particle size of the likely contaminants. The life span (in days) of the air filter given by the different suppliers is 80, 110, 100, 150, 170, 60,90,90,80, no, 90,110,80,90,160,110,90,210,160,120,110, and 110. A. R. Nassani... 

Filtration system applications include heating, ventilation, and air conditioning (HVAC), high-efficiency particulate arrestance (HEPA), and ultra-low penetration air (ULPA) filters as well as filters for automotive, beverage, pharmacy, and medical applications. Filter media for new air and liquid filtration applications, such as vacuum cleaners, are also applications of filtration systems. ... 

Weighing of solid substances will release dust. A dust extract cabinet, equipped with a High Efficiency Particulate Air (HEPA) or Ultra Low Particulate Air (ULPA) filter (see Table 27.4) in the rear wall or in the exhaust, or both, will limit the exposure of operators to active substances. Additional options are the wearing of respirators (see Sect. 26.4.1) and a closed weighing vessel. 

After passing a coarse pre-filter and a final ULPA filter the exhausted air can be exhausted into the preparation room. It that case the unit is recirculating the air. It is possible to discharge the air via a duct outside the building. As a result the room pressure will become lower. 

Check the unit once a year on air velocity a leak test for HEPA or ULPA filters is easy to perform by an expert. 

During a change of the pre-filter the operator has to wear a protective P2- or P3 mask (see Sect. 26.4.1) for dust and aerosols. The exhaust unit fan is switched on, so dust particles are trapped in the HEPA or ULPA filter cassette. Clean the filter frames and remove the old filters in a closed bag. 

Class I A BSC that protects personnel and the environment but does not protect the product/prepara-ti(Mi. Personnel protection is provided when a minimum velocity of 75 linear feet/min of unfiltered room air is drawn through the front opening and across the work surface. The air is then passed through a HEPA/ ULPA filter either into the room or to the outside in the exhaust plenum, providing environmental protection. 

The cleanroom level has above-the-ceiling air-distribution boxes, an ULPA-filtered ceiling and a perforated raised floor that stands two feet above the concrete waffle slab. ULPA (Ultra Low Penetration Air) filters provide 99.999 percent efficiency on 100 nm particles, as compared to FiEPA (Fiigh Efficiency Particle Air) filters which provide 99.97 percent efficiency on 180 nm particles. ULPA filters are generally used in facilities with cleanliness levels below ISO Class 4 (formerly Class 10). 

TABLE 8.1 Filtration efficiencies for electrospun nanofiber mats of polysuKone compared to commercial HEPA and ULPA filter paper... 

Mil F-51,068F Filters, Particulate (High-Efficiency, Fire Resistant) lES RP-CC021.1 HEPA and ULPA Filter Media lES RP-CC001.3 HEPA and ULPA Filters... 

Another manual control switch is required for shutting down the recirculating fans (which supply air to the HEPA/ULPA filter ceiling of the cleanroom) and shall be installed at an approved location outside the fabrication area. We recommend that one switch be provided for the makeup air and exhaust fans, with a separate switch for the recirculating HEPA fans. 

Very recently, Wang et al. [11] first fabricated PA-66 nanofiber/net (NFN) membranes that comprise common electrospun nanofibers and two-dimensional (2D) spiderweb-like nano-nets via electrospinning/netting (ESN) technique (Fig. 12.3a). As the second doorkeeper, the average pore size of nano-nets (118 nm) is smaller than the size of test NaCl particles (300 nm), so the nano-nets could filter the nanoparticles mainly through interception mechanism. The filtration efficiency of NFN/PP composite filter was 99.9 % (Fig. 12.3b, c), which can be used as the core filter medium in the air filtration field, such as respiratory protection equipment, HEPA filters, and ultralow penetration air (ULPA) filters. 

Table 6.3 shows the many standards for efficiency testing of HEPA and ULPA filters. New classifications have been defined for both types of filter according to EN 1822 and these are given in Table 6.4. The system is based on letters and figures in the same way as for coarse and fine filters according to the EUROVENT Classes, with H standing for HEPA and U for ULPA. The filters are then divided into eight classes from HIO to U17, depending on their efficiency at the most penetrating particle size (MPPS) and the size of the leaks.

There is a wide range of coverage of both gas and liquid applications, although the publication process is by no means complete, nor is the revision of standards in rapidly developing fields. Some standards, of course, are vital and broad-ranging, such as the BS EN 1822 series on HEPA and ULPA filters, or EN 779 for the determination of the performance of particulate air filters. 

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