Crystal Style Retractable Ceiling Fan Fanaway Ceiling Fan,Foldable Ceiling Fan,Crystal Ceiling Fan With Foldable Blades,Fan With Retractable Blades JIANGMEN ESCLIGHTING TECHNOLOGY LIMITED , https://www.jmesclightingfan.comButterfly valve installation and maintenance 1, the installation, the valve to stop in the closed position. 2, the opening position should be determined by the rotation angle of the disc. 3, with bypass valve butterfly valve, open the bypass valve should be opened before. 4, should be installed according to the manufacturer's installation instructions, the weight of the butterfly valve, should be set up a solid foundation.