An inlet port 4 and an outlet port 5 which are open in a body housing 2, an air-blowing pathway 20 disposed inside the body housing 2, making the inlet port 4 and the outlet port 5 communicate with each other, and also having a plurality of divisional pathways 22 obtained by division with partition plates 21, an air-blowing fan 7 disposed upstream from the divisional pathways 22 inside the air-blowing pathway 20, a removable inner cover 10 covering the divisional pathways 22 and having an inner surface which forms a side wall of the air-blowing pathway 20, and a removable exterior cover 9 covering the inner cover 10 to form an outer surface of the body housing 2 are provided, and the inner cover 10 has marking portions 11 formed on an outer surface along the partition plates 21.
