METHOD FOR JUDGEMENT OF REMAINING LIFE OF AIR FILTER

PROBLEM TO BE SOLVED: To judge a remaining life of a filter material during service by a method wherein a part of the filter material of an air filter is contained in a measuring pipe, a time wherein an outflow gas concentration reaches a specific value is measured by passing three or more kinds of gases of different concentrations, and a straight line having the same gradient as that of a relation between a preliminarily obtained outflow gas concentration and time, is specified. SOLUTION: Three or more kinds of gases of different concentrations are prepared, they are made to pass through a measuring pipe containing a filter material for arresting substance composing a gas, and a time wherein an outflow gas concentration reaches a specific time is measured (a first measured value processing process). Then, a part of the filter material constituting an air filter during service is sampled, and a time tb wherein the outflow gas concentration reaches a specific value under the same condition (gas of a specific concentration B1) is measured (a second measured value processing process). Then, a straight line L2 which passes a coordinate b, and is equipped with the same gradient as that of the straight line L1 specified in the first measured value processing process, is specified. Thereafter, a remaining life of the filter material of the air filter during service is judged based on the straight line L2.