When the high pressure gas emptying,the noise can be reached more than 120 db . As per Part 8 of workplace physical factors measurement in GB/T189.8 , contact time limit for 8 hour with the noise in the workplace: 85db. My company developed that the high-pressure muffler can be controlled below 75 db, when the High pressure gas discharging volume. It has been got a very high reputation in the industry.