Noise reduction measures and performance tests of positive pressure protective suits for biosafety level-4 laboratories

To reduce the noise in positive pressure protective suits,a self-designed composite muffler is installed at the end of the diverter air tube.Under three air supply pressure conditions,the internal noise,pressure difference,and air supply flow rate are tested before and after noise reduction by the positive pressure protective suit.Before wearing,the noise of the positive pressure protective suit before noise reduction is in the range of 84.5 to 98.4 dB,and it decreases to 69.2 to 77.6 dB after noise reduction,with a maximum reduction of 20.8 dB.After wearing,the noise before noise reduction is 71.5 to 83.4 dB,and it is 56.8 to 72.7 dB after noise reduction,with a maximum reduction of 14.8 dB.Whether before or after wearing,the air supply flow rate before and after noise reduction is greater than 300 L/min,and the pressure difference before and after noise reduction at the maximum flow rate is greater than 100 Pa.The results show that the installation of the muffler can effectively reduce the noise inside the positive pressure protective suit,has little impact on the internal pressure difference and air supply flow rate,and meets the relevant standards while improving the comfort of laboratory technicians.