This valve shown above is a quality product at a low cost. The version I use is a 12 volt DC unit. It has 2 inch NPS threads which can easily attach to 2 inch PVC pipe.
The air freight from China costs more than the valve.
I will be ordering a number of valves from Covna that will be sent to me via ship. The per unit shipping cost will be approximately $15.
IF YOU EXPECT TO BUY SOME VALVES FROM ME, PLEASE TELL ME.
The spring on the pressure relief valve should be set so that the valve opens when the Ball Valve is shut. The pressure relief valve should close when the Ball Valve opens and allows the Spray to begin.
The circuit card in front of the 12 volt battery contains a heat sensor, a transistor and a resistor. It is just a quick design to get started. It cannot be programmed to activate the ball valve at a desired temperature.
When a fire is detected by the heat sensor, the electric ball valve is opened and the SprayHose starts spraying.
Many heat sensors (thermistors) can be placed around the outside of a house attached to the same wire pair. Any heat sensor that detects heat will open the 2-port valve.
The Green wire is connected to the GND position. GND is the battery Negative.
The GND on the right side of the photo is connected to the GND on the left side.
The three colored wires come out of the right side of the board and go to the next board.
The Plus on the 12 volt battery is connected to the Red wire and to the "+12V" on all of the circuit boards. The "+12V" on each board is connected to the other "+12V" on the board.
The "IN Motor" and "OUT Motor" on each board are connected together.
The jumper on the left side of the board selects the Fahrenheit temperature that will cause the 2-Port Valve to open.
A Thermistor connects to the Center Connector.