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Pump Noise Measurement and Evaluation Method (National Standard) (with photos)
GB 10890-89 Methods of measurement and evaluating noise of pumps The methods for the determination of sound power levels in this standard are equivalent to the International Standard ISO 3746-1979, "Acoustics - Determination of Sound Power Levels of Noise Sources - Estimation Methods". 1, the main content and scope This standard specifies the pump noise measurement and evaluation methods. This standard applies to submersible pumps, reciprocating pumps other than the various types of pumps and pumps with speed hydraulic coupling. In the application of this standard should be given priority to select the sound power level method, the conditions are not used only when the sound pressure level method. In case of dispute, the sound power level shall prevail. 2, the standard reference GB 3102.7 Acoustics and units GB 3240 commonly used in acoustic measurement frequency GB 3241 sound and vibration analysis with 1/1 and 1/3 octave GB 3768 noise source sound power level measurement Simplified GB 3785 sound level meter electrical, acoustical grade and test methods GB 3974 Acoustics terminology JJG 176 sound pressure level calibrator test procedures JJG 188 sound level meter test procedures JJG 277 standard sound source test procedures 3, the pump sound power level Determination methods The sound power level determined in this standard method is consistent with the method specified in GB 3768, the application of this method can more accurately understand the pump or pump noise level. When it is necessary to accurately determine the sound power level of the pump sound source, the influence of the noise of the prime mover (motor, internal combustion engine, etc.) should be taken into account. If necessary, measures should be taken to reduce the influence such as sound insulation cover of the prime mover. 3.1 Measurement Error Measurement error refers to the cumulative standard deviation caused by various factors. According to this standard, the error of the sound pressure level of the pump is: a. For the pump sound source, the standard deviation is not more than 4dB; b. When comparing the same type of pumps in the same test environment, the standard deviation is not more than 3dB. 3.2 Acoustic measurement environment Ideal acoustic measurement environment should be in addition to a reflective surface (ground) no other reflective objects. Above the reflecting surface is approximately a free field. Suitable for this standard measurement environment for a wide range of outdoor or meet the requirements of the room. Measuring pump noise are generally in the laboratory (test pump). 3.2.1 Requirements for measuring environment (test room, test pump room) The standard for evaluating whether the laboratory meets the requirements is A / S ≧ 1 (A is the sound absorption in the laboratory room and S is the area of ​​the measuring surface) or the environment Correction value K2≤7. 3.2.2 Background noise requirements At the measuring point, the difference between the A level of the A level and the background level and the A level of the background level measured by the pump should be at least 3dB or more. 3.2.3 Wind speed outdoor measurement, the wind speed should be less than 6m / s and should use the hood. Outdoor measurement, the motor cooling ventilation (feel) should use the hood. 3.3 Test Equipment 3.3.1 Overview Test equipment should be used in GB 3785 Type 2 or above sound level meter, and the accuracy of other test equipment. It is best to use extension cables or extension rods between the sound level meter or other test equipment and the microphone. 3.3.2 Calibration Before and after each measurement, the entire test system (including the cable) should be calibrated at one or more frequencies with a sound level calibrator better than ± 0.5dB. Sound level calibrator shall JJG 176 procedures, sound level meter and other test equipment shall be regularly verified JJG 188 order to ensure the accuracy of test equipment. 3.4 Pump Installation and Operating Conditions 3.4.1 Installation When installing the pump and test equipment should note the following: a. In the laboratory measurement, the outlet throttle valve should be installed at a distance from the pump; b inhalation and Exhaust pipe noise is too large, should take measures to reduce the impact of noise; c. Should be to minimize the impact of noise from other test equipment. 3.4.2 Operating conditions In the measurement of centrifugal pumps, mixed flow pumps, axial flow vane pump noise, should be in the specified speed (± 5% tolerance), the provisions of the flow rate. In the measurement of gear pumps, vane pumps, screw pumps and other positive displacement pumps (Exhaust pump excluded) noise, the speed should be specified (± 5% tolerance), the provisions of the working pressure. 3.5 A Measurement of sound level 3.5.1 Measuring surface The microphone should be located on the imaginary measuring surface of the envelope sound source with one of two measuring surfaces available: