... oil mist, vapor, high temperature gas not arise the dustperforation muffler has small resistance loss. Checke 1,Mufflers Type WX, ... , because of different perforation and double-layer perforation. This muffler can eliminate noise in low frequency; in middle frequency.2 ... contioners and ventilating pipes.3,perforation muffler has small resistance loss. Checked, the muffler has a resistance 0.7-3mmH20 ...