DIN 45635-56:1986 Measurement of noise emitted by machines; airborne noise emission; enveloping surface method and in-duct method; fan-assisted warm air generators, fan-assisted air heaters and fan units of air handling devices
1986DIN 45635-56:1986 Measurement of noise emitted by machines; airborne noise emission; enveloping surface method and in-duct method; fan-assisted warm air generators, fan-assisted air heaters and fan units of air handling devices