Fuel shut-off valves are important components within a system as they represent a positive action safety device. The main role played by this device is to intercept and block the fuel before it reaches the burner, thus avoiding the boiling temperature of the circuit entering the system from being reached. This represents a method to avoid damage to the system itself but also to the persons who are in the vicinity of it.

How does the fuel shut-off valve work?

There are two fundamental components of the valve:
- The valve body: within which the fuel, liquid or gaseous, passes;
- The control device: equipped with a sensitive element.
The shutter rod is connected to the control device and causes the closing of the valve if necessary. If everything works correctly, the shutter rod rests on the piston and ensures the passage of fuel. However, if malfunctions or anomalies occur, the piston moves and causes closure by lowering the shutter rod. What are these cases?
- Excessive expansion of the fluid: the piston moves to the left and causes the rod to descend, closing the fuel passage;
- Breakage of the capillary: the piston moves to the right and causes, once again, the descent of the rod with consequent closure of the passage.
Once the valve closes, it is possible to return to functionality only by means of a manual reset which can only take place if the fluid has a temperature below 87 ° C and the capillary is not broken or damaged.