| 摘要 |
PROBLEM TO BE SOLVED: To simply and accurately examine a contamination of a filter material of an air filter which accompanies performance deterioration and to judge a suitable replacement time of the air filter. SOLUTION: An air-impermeable small piece 30 is peelably bonded on the air inflow side surface of the filter medium 10 of the air filter 1. A product number 31, a product bar code 32, etc., of the air filter are indicated at a part to be peeled of the small piece 30. When the small piece is peeled, an unsoiled beautiful surface is exposed and the variation in contamination of soiled filter medium surface is quite obvious since the air containing the dust, etc., to be filtered is intercepted by the small piece and a filter medium part at the position at which the small piece is bonded is heat in clean state just after the factory shipment. The peeled small piece is used for writing order or the like thereon when the filter is replaced. |
