Filter testing, filter test standards, and filter ratings

2022 ◽  
pp. 119-144
Author(s):  
Wallace Woon-Fong Leung
Keyword(s):  
2020 ◽  
Vol 41 (6) ◽  
pp. 758-771
Author(s):  
Jing Ee Yit ◽  
Bee Teng Chew ◽  
Yat Huang Yau

Air filters play an important role in a heating, ventilation and air-conditioning (HVAC) system to maintain good indoor air quality of a building. The air filter test standards act as a guideline to evaluate the air filter performance. The current global test standard, ISO 16890:2016 adopts particulate matter classification which can be easily understood. The European standard, EN 779:2012 is obsolete and replaced by ISO 16890:2016 in June 2018. ASHRAE 52.2:2017 which adopts the minimum efficiency reporting value (MERV) classification is still widely used in the United States. Some countries in Southeast Asia such as Malaysia, Brunei and Singapore are applying different standards: EN779, ASHRAE 52.2 and ISO 16890. A standardization of the air filter testing and classification is undoubtedly important in the global air filtration market. This paper can act as a reference and assist these developing countries in adopting the suitable air filter testing standard to develop their national standard. As all three standards have no specifications on energy efficiency classification, the energy rating system can be obtained using Eurovent 4/21-2018. The HVAC-system-supplied air quality can be further improved with the consideration of WHO annual mean pollutant limits and EN 16798-3 air classification to determine the supply air cleanliness. Practical application: Although EN 779 is replaced by ISO 16890, some developing countries are still in the transition period. Manufacturers and consumers apply different standards which are EN 779, ASHRAE 52.2 and ISO 16890; therefore, a global filter testing standardization is important. This paper can act as a reference and assist the countries in other regions especially in Southeast Asia to develop respective national standard. Besides, some recommendations are given to improve the air filtration and ventilation system by referring to the WHO guidelines for the air pollutant limits, EN 16798-3 for the supply air quality and Eurovent 4/21 for the air filter energy rating.


1996 ◽  
Vol 76 (03) ◽  
pp. 460-468 ◽  
Author(s):  
Francesco I Pareti ◽  
Marco Cattaneo ◽  
Luca Carpinelli ◽  
Maddalena L Zighetti ◽  
Caterina Bressi ◽  
...  

SummaryWe have evaluated platelet function in different subtypes of von Willebrand disease (vWD) by pushing blood through the capillarysized channels of a glass filter. Patients, including those with type IIB vWD, showed lower than normal platelet retention and increased cumulative number of blood drops passing through the filter as a function of time. In contrast, shear-induced platelet aggregation, measured in the cone-and-plate viscometer, was paradoxically increased in type IIB patients. Treatment with l-desamino-8-D-arginine vasopressin (DDAVP) tended to normalize the filter test in patients with type I-platelet normal and type I-platelet low vWD, but infusion of a factor VUI/von Willebrand factor (vWF) concentrate lacking the largest vWF multimers was without effect in type 3 patients. Experiments with specific monoclonal antibodies demonstrated that the A1 and A3 domains of vWF, as well as the glycoproteins Ibα and Ilb-IIIa on platelets, are required for platelet retention in the filter. Thus, the test may reflect vWF function with regard to both platelet adhesion and aggregation under high shear stress, and provide relevant information on mechanisms involved in primary hemostasis.


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