2 specification for indirect gas fired forced convection air heaters with rated heat inputs up to 2 mw for industrial and commercial space heating : safety and performance requirements excluding electrical requirements 2nd family gases 工业和商业用对流式加热用额定热输入功率达2mw间接燃气强制对流式空气加热器规范:安全和性能要求
This will be dealt with in this paper . the discrimination for noise source from qn700 indicates : the fan noise ( 625hz ) , the electromagnetism noise ( 962hz ) and the burning noise are the main noise sources 对汽车燃油空气加热器中具有典型代表结构的qn700型样机的测试分析表明：风扇噪声( 625hz ) 、电机噪声( 962hz )和燃烧噪声是加热器的主要噪声源。
As a heating equipment for coach in winter , the air fuel fired heater has been adopted largely , which inevitably causes some noise . to meet the need for the environment protection and the full comfort , some studies on how to reduce the noise seem to be very necessary to do 为充分满足人们对环境保护和乘坐舒适性越来越高的要求，本文对国产汽车燃油空气加热器的噪声性能进行了全面的试验研究，找出了主要的噪声源，并采取了相应的降噪措施。
