This kind of Double Block and Bleed Valves Have got a patented design and style which includes two ball valves and a bleed valve into just one compact cartridge type device with ANSI B16.five tapped flanged connections. Used for important course of action company, double block and bleed valves are http://dbbvalve62738.articlesblogger.com/11569297/getting-my-double-block-and-bleed-valve-to-work