Filters efficiency testing

DOP (Dioctylphthalate) Generated particles of this chemical are used in filter efficiency tests. 

A filter efficiency test according to the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) Standard 52.1 (ASHRAE, 1992) that utilizes an ASHRAE synthetic dust and the mass fraction of dust removed is determined. 

EN 779 1993 in principle contains two different test methods. The filter is tested both with untreated outdoor air and with the addition of synthetic dust. In the first case, the filter s dust spot efficiency is determined, i.e., its capacity to clean normal outdoor air. In the second case, the filter s arrestance is measured, i.e., its capacity to separate synthetic dust. The average value for dust spot efficiency or arrestance during the course of the test is used for classification of the filter. 

Air filter test Any test to determine filter efficiency, flow rates, or other characteristics by some preset method. 

Sodium flame test A test of HEPA filter efficiency using small particles generated from NaCl. 

Efficiency testing of high-efficiency partieulate air (HEPA) filters used for the supply of sterile air to aseptie workplaces (Chapter 22) is normally achieved by the generation upstream of dioetylphthalate (DOP) or sodium ehloride particles of known dimension, followed by deteetion in downstream filtered air. Retention efficiency is reeorded as the percentage of partieles removed under defined test conditions. Microbiological tests are not normally performed. 

The collection efficiency of the Mitex and Fluoropore filters was tested by generating and collecting mixed aerosols containing MMA, DMA and p-APA under controlled conditions and analyzing the resulting filter extracts by the developed analytical technique. 

Other Interferent Studies with Nylon Filters. Retention of HONO on Gelman Nylasorb (nylon 6) filters was tested 0.3 to 1 xg/m3 HONO was sampled in air (—50% RH) at 20 L/min with 47-mm filters for 16-23 h. At saturation, the filters contained 1.8 xg/cm2 N02 this result indicates less than 50% efficiency for HONO retention (19). Sampling 440 xg/m3 HONO at 20 L/min with 47-mm Gelman Nylasorb filters (nylon type unstated), Sickles and Hodson reported about 25% retention efficiency, with a similar saturation value, and noted that such retention was reversible. Substantial oxidation of HONO to N03 on the filter surface by 03 was demonstrated in laboratory and atmospheric trials (21). Perrino et al. (20) observed with 47-mm Gelman Nylasorb (nylon type unstated) filters an efficiency for HONO that increased from about 25 to about 90% as the flow rate decreased from 12 to 2 L/min, with saturation at —50 xg/filter. Nitrite to nitrate conversion on the nylon filter surface increased from 13% at 45 ppb 03 to 93% at 200 ppb 03. 

Individual HEPA filter efficiencies are established by an exacting challenge of the filter frame and medium, usually incorporating a cold-boil, polydisperse aerosol of dioctylpthalate (DOP) or equivalent, which is introduced into the upstream plenum-side of the filter in a manner that ensures even distribution of the test aerosol behind the filter, at its rated airflow. 

This research is being performed in two phases evaluation of pressure drop and flow characteristics of cold flow models of the filter and collection efficiency tests with a pilot-scale filter coupled to a 4.S tonne per day biomass gasifier. In this paper we describe three fluid dynamic design features developed in the cold flow model that improve performance of the Alter. 

Filter classes should always be linked to the standard test method because referring to actual filter efficiencies can be very misleading (as... 

The leak test ( DOP test situ test to verify that filters do not leak on inatidlation. The leak test is not a second efficiency test. It is intended to dis> close leaks around the frames and damage to the filter medium. An aerosol of oil particles with mass median diameter of 0.3 pm is used to challenge the filter deteaion Is by aerosol photometry on the downstream side. Standards of integrity are specified as maximum permissable percentages of the upstream concentration of particles that can be recovered downstream of the filler. 

Validation of performance on installation, planned maintenance, and frequent checks on performance are essential for critical items of equipment such as sterilizers, air filtration systems and stills. For example, checks on steam and hot air sterilizers should include heat distribution arid heat penetration studies, and on air supply systems and tests of filter efficiency. Details of maintenance operations and performance checks should be recorded. 

The pressure drop across charcoal filters must be checked periodically to verity that the appropriate filters are in sen/ice. Charcoal filter operating records must also be checked periodically to verity that the filters have been in service for a period not exceeding 5 years. The pressure drop across the in-service hot exhaust HEPA filter must be checked periodically to ensure continued performance capability. Additionally, periodic in-place testing of HEPA filters must be performed to verity filter efficiency. 

Ventilation Hot Exhaust (Zones 1 and 2A combined exhaust) Control of off-site radioactive material releases. 1. Hot exhaust confinement boundary integrity must not be compromised by ventilation system fan mis-operation or malfunction. 2. HCF operators must maintain the required functional performance of confinement controls. 3. HCF operators must verify the functional performance of the hot exhaust HEPA filters. 1. A ventilation system fan sequencing interlock ensures that the backup exhaust fan is automatically started upon loss of the primary operating fan. An aiann alerts the operations staff upon loss of the operating stack exhaust fan. 2. Administrative controls are in place to ensure periodic ventilation system fan sequencing interlock testing. 3. Administrative controls are in place to ensure periodic functional performance and efficiency testing of the HEPA filters. 

HEPA filter performance for the removal of radioactive particulate matter in the ventilation system hot exhaust is ensured by means of administratively controlled TSR surveillance activities. HEPA filters are subject to periodic pressure drop testing to verity operability (i.e., to verify that the filters are not plugged). They are also subject to periodic efficiency testing to verify the required level of particulate matter removal efficiency. HEPA filters are to be replaced, In accordance with operating procedures, when they become plugged or when the required efficiency can no longer be achieved. 

Quantitative relationdiips for the pressure differential created by hquid flow through nonwovens are presented below. The question of filter efficiency is also discussed, with reference to laboratory tests for particle retention. 

Filter media efficiency tests are made using dilute suspensions of standard particles. A wide variety of test powders is available, in fine and coarse grades. Industrial users will tend to use a test mixture typical of the products of interest, e.g. yeast in the browing industry. In the gaseous field, both solid (sub-micron sodium chlorid crystals) and liquid particles (di-octyl phthalate dispersion) are used. 

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