GB7786-87 Noise Rating Limits of Air Compressors and Diaphragm Compressors for Power Purpose
I. Introduction
The noise rating limit of air compressors and diaphragm compressors for power purpose is regulated by the national standard, GB7786-87. This is established by the Ministry of Machinery Industry of People’s Republic of China to set out the noise rating limit of air compressors and diaphragm compressors for power purpose. The standard is intended to ensure the products and services that meet the requirements of customers and industry standards and to reduce the negative impacts to people and environment due to the noise generated from the operation of air compressors and diaphragm compressors for power purpose.
II. Definition
1. Noise Rating Limit: This refers to the noise level value, expressed in dB (A) which should not be exceeded at the Operational Position within 1m away from the center of the equipment.
2. Operational position: This refers to the position at which operator shall work.
III. Categories
The noise rating limit is divided into two categories according to the product power range:
a) Category A: applicable to products of power below 4kW.
b) Category B: applicable to products of power above 4kW.
IV. Limitation
A. Category A:
The noise rating limit of product of power below 4kW is 75dB (A).
B. Category B:
The noise rating limit of category B product varies according to the power range. For example, for products with the power range of 4kW~100kW, the limit is lower than 95dB (A).
V. Testing
A. Test Conditions:
1. Test environment should be ventilated but without wind interference.
2. Test instrument shall be an electronically operated sound level meter with A-weighting network and should comply with the requirements of GB/T 13425-2005.
3. The microphone should be placed at the operational position within 1m away from the center of the equipment in horizontal direction.
B. Test Methods:
Test procedures should be in accordance with GB/T 3321-1982 “Industrial Environmental Noise Measurement Method” and GB/T 3322-1982 “Industrial Environmental Noise Test Instrumentation Collocation and Measurement Test Method”.
VI. Test Record
The test record should include the following items:
1. Test environment information
2. Test instrument model and standard
3. Test results
VII. Conclusion
This standard is established by the Ministry of Machinery Industry of People’s Republic of China to set out the noise rating limit of air compressors and diaphragm compressors for power purpose. The noise rating limit of air compressors and diaphragm compressors is classified into two categories according to product power range. The test shall be conducted in accordance with the relevant procedures and test record should be made to illustrate the test details. Thus, this standard ensures the products and services that meet the requirements of customers and industry standards and to reduce the negative impacts to people and environment from the operation of air compressors and diaphragm compressors for power purpose.
