(3). The water flow indicator
The flow indicator is installed in the pipeline, when there is flow of water goes through the pipe which is more than scheduled flow, the water flow indicator emits electrical signals, shows the flow of water. Usually the flow indicator is settled on the distribution pipe of the fire fighting sprinkler system, when the nozzle opens, nozzle position to a central control room fire instructions open partition, sometimes also can be located in the tank outlet pipe, once the system is open, the tank water is used, the flow indicator emit signals through the central control room fire or directly start the fire pump water supply.
a. the oar chip flow indicator
Oar chip flow indicator, when there is water flow in side the pipe, the water flow drives the blades, the normally open contacts connected and output alarm signals. Oar chip flow indicator is always used for wet automatic sprinkler fire fighting system. Should not be used for dry and preaction system. Because in the dry and preaction system, usually there is no water in the pipe, once the fire happens, after the open of the automatically alarm valve, due to the sudden shock of water, it is likely to make the blades or other mechanical parts were damaged. So when the wet type system for the first time after water filling or maintenance to water filling, should be to prevent the sudden impact of water flow. In order to prevent due to hydraulic transient surge away after 15-20s delay to report to the alarm.
b. the water valve
Water valve, when the water flow through a pipeline, the valve plate swing, and the valve spindle rotation, then by the micro switch to send electrical signals. Water flow movement valve can be used in any system, will not damaged by water.
c. the specifications of the water flow indicator
The world’s most used is oar chip flow indicator. Our production flow indicator of nominal diameter is: used on pipeline of 50, 70, 80, 100, 125, 150mm; British production flow indicator of nominal diameter: 50, 65, 75, 125, 150, 200mm.
Some manufacturer production flow indicator can adjust the length of the blades to install on the different nominal diameter pipe. The working voltage of water flow indicator is commonly DC 24V.
d. pressure switch (pressure relay)
Pressure switch is to transfer the water pressure fluctuation into electrical signals and sent to the central control room, or directly send electrical signals to open the pump or send the alarm. Pressure switch can be installed on the alarm signal tube or hydraulic system pipe network.
Alarm switch is usually installed on the signal pipe between the alarm valve and alarm bell to realize electric alarm and open water pump. This electric alarm in the system can be used as auxiliary alarm device, but can not replace hydraulic alarm device. Such as: when the system adopts the stabilized pressure pipe to maintain the water pressure, the pressure switch can be installed in the network to monitor hydraulic condition of the system, when the water pressure is lower than a set value, automatic open voltage stabilizing pump; when the water pressure is higher than a certain value, stop the pump automatically; when there is water pull out of the nozzle, water pipe network pressure during the voltage stabilizing pump still continues to fall to a set pressure, the main pump automatic start, then usually you need to set up three pressure switch to regulated respectively pump, main pump and standby pump start-up control.
e. the end test device
At the end of automatic sprinkler system water pipe network and the worst point of each layer shall be set test device.
The end test device generally includes the pressure gauge, sluice valve or solenoid valve and water testing orifice, the orifice should be the same as the nozzle orifice diameter. The diameter of the connection pipe should not less than 20 mm.
The end water testing device is used in maintenance and management, to regularly check system, to make sure the system can work normally.
The end testing valve can use the manual valve or solenoid valve. In the fire control room, if the solenoid valve is adopted, we can directly control the test valve from the central control room, which is convenient for checking.