Conditioning Air Filters with IPA Vapor
Monroe A. Britt Green Leaf Technologies
[email protected] NAFA TECH2012 Phoenix, AZ April 19, 2012
HVAC General Ventilation Air Filters Medias used in air filters may contain an electrostatic charge Charged medias may cause increase in particle size efficiency Charged medias may decrease in efficiency over time • charge may dissipate • charge may become masked by dust particles Installed filter may not be providing degree of protection as believed by user and required for intended purpose
Possible Causes for Reduced Filter Efficiency High humidity Sensible moisture Elevated temperature Atmospheric dust particles • Cigarette smoke • Diesel fume Atmospheric aerosols • Cooking oil • General hydrocarbons Etc. Etc, Etc
Not all charged medias response to all contaminants to same degree
Recommended Reference ASHRAE Research Project ---- RP 1189
“Investigation of Mechanisms and Operating Environments that Impact the Filtration Efficiency of Charged Air Filtration Media”
VTT Technical Research Centre of Finland VTT Industrial Systems Matti Lehtimaki – Chief Research Scientist
Why “Condition” Filters? To provide lab test results that better conform to “real life” service performance ---- better “apple-to-apple” comparisons Same filter performance can vary greatly from site to site No one lab test method can accurately predict filter “real life” service performance --- true for charged or un-charged medias User of filter should be made aware of the possibility of efficiency decrease and to what extent would be expected under typical severe environmental conditions Air filter laboratory test methods require COMPROMISE
Current Methods of Conditioning Air Filters
• ASHRAE 52.2 -- Informative Appendix J Conducted on full size filters and establishes MERV A ranking and MERV A Dust Holding Capacity • EN 779 -- conducted on flat sheet media or filter section , presently test data not used to assign G and F numbers
ASHRAE 52.2 KCl Conditioning Procedure • Feed very large concentration (106 particles/cm3) of very fine KCl particles (less than 0.1 microns) until: a. Efficiencies meet “convergence” criteria (