Abstract:Abstract:
To meet the needs of society, Metrology institute of shandong province recently build a new critical sonic nozzle gas flow standard device,diameter:DN15~DN600,flow range:(0.1~15000)m3/h,the expanded uncertainty:Urel=0.25%,k=2。Due to the large flow, in order to ensure the testing lab in the process of constant temperature, the device using the circular air way,The test medium (air) through the vacuum pump after not directly to the outside, but after underground circumfluence channel flow back to the laboratory. After using circulating air way, the laboratory temperature fluctuations are small, constant temperature effect is obvious, but the disadvantage is that there's so much noise in the laboratory. Through the analysis, Laboratory noise source includes three main air blower, and three auxiliary air blower, they are all roots blower which placed centrally in the sound-proof room. Noise into the laboratory, there are three main ways: 1) through a soundproof room wall plate transmission; 2) through the device test pipe; 3) through the wind channel directly in the laboratory. Roots blower due to the high sound level, outlet noise elimination measures were not taken, the noise is very big, the laboratory does not favor the staff's health, at the same time also have certain influence to environmental noise, noise control is required.
Management plan is as follows: 1) processing of sound insulation room: sound insulation paste absorption body interior walls including roof, cushion between blower and base installation, maintenance personnel to sound insulation door instead. 2) the processing of blower inlet: import mounted muffler straight section of each test. 3) blower outlet: within the wind channel designed deadened the noise of a large room, increase the pump gas channel sound barriers and sound-absorbing cotton, to control the voice sound indoor, cut off the route of transmission.
Before and after noise control data see table 1. Through experimental data can be concluded that compared before modification, and modification after the control room and the hall fell (20 ~ 30) decibel noise, the noise reduction effect is obvious, resonance effect, the noise condition has meet the requirements of the work environment.
As the flow measurement device to large areas of development, device noise pollution become a problem to be solved before the flow metering workers, through their own practice, the writer hopes to solve related problems provide some useful reference.