Flow indicator is applicable to the mirror instrument valve oil, chemical, chemical fiber, medicine, food, electric power plant, pump and other industrial production line, through the window to observe the dielectric liquid, gas, steam and other turbidity measurement and medium flow velocity response, is one of the indispensable pipeline accessories product quality guarantee normal production guarantee. The connection modes include thread type, flange type and welding type. Water flow indicator can also be used for the automatic sprinkler system, it can be installed in the main water supply pipe or the bar, given a number of Telecom sub regional area of water flow, the electrical signal can be sent to the control box, but usually not to start the fire pump control switch.