The SPRD is used on zone systems when the automatic closing of various zone dampers can create an excessive increase in air pressure and velocity throughout the duct system.
SPRD旁通阀是当各种区域风门自动关闭时用在区域系统中，可以在管道系统中增加空气压力盒速度。
2
The SPRD will automatically open as the air pressure in the duct system increases, in order to prevent the reduction of air flow and excessive noise and velocity through the duct system.
当管道系统空气压力增加时，SPRD会自动开启，以防止管道系统中空气流动的减少和过度噪音和速度。
3
Presents the theoretical model of pressure drop for flexible duct.