消(xiao)聲(sheng)(sheng)器(qi)(qi)（圖4-62）通常(chang)用于(yu)介(jie)質(zhi)放空(kong)(kong)管(guan)的終端，以消(xiao)除可能因高(gao)壓高(gao)速介(jie)質(zhi)的放空(kong)(kong)而產生(sheng)的噪聲(sheng)(sheng)。通常(chang)包括(kuo)蒸汽排氣消(xiao)聲(sheng)(sheng)器(qi)(qi)、氣體(ti)排空(kong)(kong)消(xiao)聲(sheng)(sheng)器(qi)(qi)、油浴式消(xiao)聲(sheng)(sheng)過濾器(qi)(qi)、電機消(xiao)聲(sheng)(sheng)器(qi)(qi)等。

  視(shi)鏡（圖4-63）通常用于冷卻水(shui)(shui)管(guan)道和潤(run)滑(hua)油管(guan)道等(deng)，通過其透明的視(shi)窗可以觀察(cha)到管(guan)道內循環冷卻水(shui)(shui)或潤(run)滑(hua)油是否在流動。