For one of the simplest and least expensive filtration devices air filters are among the most complicated to understand. Sometimes we think the confusion is as often as not man-made.

The first thing we will try to do is help you understand what kind of filter you are purchasing.

Air Filters can be characterized technically by three measures – Arrestance, Efficiency and MERV rating. MERV rating has more or less taken over as the rating of choice for all but paint arrestance media. The technical abilities of Filters, Water & Instrumentation is to determine which MERV is rating appropriate for your application.

MERV means Minimum Efficiency Reporting Value. MERV rating is based on ANSI/ASHRAE Standard 52.2. ANSI is the American National Standards Institute. ASHRAE was formerly the American Society of Heating, Refigeration and Air Conditioning Engineers.

MERV is an attempt to standardize the efficiency ratings of air filters to give users assistance in selection of appropriate air filtration equipment. In general, the higher the MERV rating the more particles an air filter will remove from the system.