A Puncture valve is used to stop the Fuel Injection. It is a device to positively stops the engine irrespective of the rack position.

Engine stops and shutdowns are carried out using the puncture valve.

It is fitted on the top part of the Fuel Pump.

A puncture valve in a fuel pump is a type of relief valve that helps to protect the fuel pump and other engine components from damage caused by excessive pressure. The fuel pump in a diesel engine is responsible for delivering fuel from the fuel tank to the injectors, which then deliver fuel to the combustion chamber.

Under normal operating conditions, the fuel pressure in the system is regulated by a pressure regulator. However, in the event of a malfunction, such as a clogged fuel filter or a malfunctioning pressure regulator, the fuel pressure can increase beyond safe levels. This can cause damage to the fuel pump, injectors, and other components, as well as potentially creating a safety hazard.

The puncture valve is designed to prevent this by opening and releasing excess pressure when the pressure in the fuel system exceeds a certain threshold. This helps to protect the fuel pump and other components from damage, as well as ensuring that the engine operates safely and efficiently.

In summary, a puncture valve in a fuel pump is a type of relief valve that helps to regulate fuel pressure and prevent damage to the fuel pump and other engine components.

Function and Working of Puncture Valve:

A Puncture valve is operated with starting air which is sent during Stop, Emergency Stop or in event of actuation of the shutdown system of the main engine.

It reduces the high pressure of the fuel oil by connecting the high-pressure side to the pump body, thereby stopping the injection of the fuel.

Puncture Valve

The puncture valve is operated in the event of actuation of the shutdown system, during the air start sequence or when excessive leakage is detected from the double skinned fuel pipes. 

Puncture valve actuation returns the fuel oil to fuel pump housing and no injection takes place.

If allows fuel recirculation when the engine is stopped since oil pressure is not totally bypassed.

It is operated by pneumatic air pressure.

It is used in MAN B&W engine. 

• Tips:A puncture valve is fitted in the top cover of the pump. It is opened when compressed air from the control air system acts on top of a piston fitted in the top cover. Fuel oil from the discharge side is then returned to the suction side of the pump and no injection takes place. The puncture valve is operated in the event of actuation of the shut down system (all units), during the air start sequence or when excessive leakage is detected from the double skinned fuel pipes.

• The puncture valve consists of a piston which communicates with the control air system of the engine. In the event of actuation of the shut-down system, and when 'STOP' is activated, compressed air causes the piston with pin to be pressed downward and 'puncture' the oil flow to the fuel valve. As long as the puncture valve is activated, the fuel oil is returned through a pipe to the pump housing, and no injection takes place.

• MAN B&W reversing: Reversal of the fuel pump follower only takes place while the engine is rotating. If the engine has been stopped from running ahead and started astern,the fuel pump follower will move across as the engine starts to rotate and before fuel is admitted by venting the fuel pump via the "puncture" valve.