Series 50 – Section 2.45 Fuel Shutoff Valves for the Series 50G Engine Prior to 1998

Section 2.45
Fuel Shutoff Valves for the Series 50G Engine Prior to 1998

Fuel shutoff valves are required for safety and maintenance. Series 50G installations utilize shutoff valves controlled by DDEC and GFI in addition to manual shutoff valves. See Figure "Compressed Natural Gas Fuel System Description" .‪

Figure 1. Compressed Natural Gas Fuel System Description

The manual shutoff valve is located upstream of both gas filters in order to facilitate element replacement. The manual shutoff valves should be readily accessible for safety and service.‪

The DDEC controlled fuel shutoff valve is located downstream of the high pressure coalescing filter but as close to the fuel tank(s) as possible.‪

The GFI pressure regulator is equipped with its own integrated fuel shutoff valve. This shutoff valve is controlled by the GFI compuvalve.‪

The DDEC controlled shutoff valve will close and shut off fuel flow for any of the following:‪

1. After the ignition is switched on, the fuel supply is shut off until the engine reaches 60 r/min.
2. In the event engine speed exceeds a calibrated value, the fuel supply will be shut off.
3. If the engine speed drops below the minimum acceptable (60) r/min the engine is deemed to be no longer running and the fuel is shut off.
4. For the instances where the throttle diagnostics indicate that the throttle should be shut down, the fuel supply will be shut off.

The GFI system will shut off the fuel for the following condition:‪

After the ignition is switched on, if there is no indication of engine speed for 20 seconds, the fuel supply is shut off until there is an indication of engine speed.‪

Section 2.45.1
Replacement of the Fuel Shutoff Valves for the Series 50G Engine

Detroit Diesel does not service the fuel shutoff valves. Refer to OEM to replace as necessary.‪

Section 2.45.2
Removal of the Fuel Shutoff Valves for the Series 50G Engine

Refer to OEM for removal procedure for the fuel shutoff valves.‪

Section 2.45.2.1
Inspection of the Fuel Shutoff Valves for the Series 50G Engine

Refer to OEM for inspection procedure for the fuel shutoff valves.‪

Section 2.45.3
Installation of the Fuel Shutoff Valves for the Series 50G Engine

Refer to OEM for installation procedure for the fuel shutoff valves.‪

EXPLOSION ‪

To avoid injury from an explosion of natural gas, the following precautions must be taken:‪ Do not smoke when installing or servicing the engine or fuel system. Installation or servicing of natural gas equipment must only be conducted in well ventilated, natural gas-compatible areas. Do not install or service equipment in an enclosed area where ignition sources are present without first ensuring that an undetected gas leak may be safely vented without being ignited. Bleed natural gas lines before installing or servicing any component connected to the fuel lines. Natural gas fuel systems are pressurized. Relieve pressure from any fuel system component prior to installation or service of that component. Use a combustible-gas detector. Liquefied natural gas (LNG) is odorless and cannot be detected by smell. Compressed Natural gas (CNG) may be odorless and may not be detected by smell. Equipment fuel systems are the responsibility of the Original Equipment Manufacturer (OEM). Equipment fuel system guidelines must be closely adhered to when installing or servicing equipment. Refer to OEM guidelines specifying which maintenance procedures require venting of fuel lines and fuel tanks. LNG systems are pressurized and contain extremely cold (-162° C [-260° F]) fluids. Contact the fuel supplier or OEM for LNG safety requirements. Contact with LNG may cause personal injury (freezing). Vent systems on the equipment should be ducted to a safe area whenever equipment is in an enclosed area.