SPRING-LOADING 2W8500 - Caterpillar

The Electronic Control Module (ECM) provides control of the air/fuel mixture to the engine. Illustration 1 is a diagram of the fuel system main components. The flow of fuel through a typical fuel system is explained below.Refer to the Application and Installation Guide, LEBW5336, "Gaseous Fuel Systems" for more information on fuel system specifications and installation.
Illustration 1 g01442708The fuel flows from the main gas supply through a knock-down regulator. A knock-down regulator is a second regulator that is needed when the gas supply pressure is too high for a single regulator to manage. From knock-down regulator, the fuel flows to the fuel filter. Usually, the fuel filter is a component of the design at the particular site. The customer is responsible for supplying clean, dry fuel to the engine. The fuel filter may be supplied by Caterpillar or by the customer. To prevent particles from entering the engine, a 1 micron filter is recommended. Use a filter that is properly sized for the required gas pressure.For installation of the fuel filter, the recommended location is close to the engine before the engine gas pressure regulator. Pressure gauges in the gas lines on each side of the fuel filter are recommended in order to monitor the filter differential pressure. A manual shutoff valve in the gas line before the fuel filter will facilitate servicing of the filter.The filtered fuel flows to the Gas Shutoff Valve (GSOV). The GSOV may be supplied by Caterpillar or by the customer. The solenoid for the GSOV may be connected to engine wiring harness or to a harness that is supplied by the customer. In either case, the customer may install a switch that can interrupt the circuit.The control system is configured for a GSOV that is energize-to-run. This means that the GSOV must be energized in order for the engine to run. The GSOV may be energized by the customer equipment or by the ECM. When the GSOV is energized, the valve opens and the fuel flows to the engine. When the control system shuts down the engine, the voltage is removed from the solenoid. The valve closes and the fuel is shut off.The fuel flows through the GSOV to the gas pressure regulator. The regulator may be supplied by Caterpillar or by the customer.For parallel to utility applications, the required fuel pressure stability is 1.7237 kPa ( 0.25 psi).A regulated pressure of 7 to 35 kPa (1 to 5 psi) is recommended.For island mode applications, the minimum fuel pressure is 20 kPa (2.9 psi). Steady state fuel pressure stability requirement of 6.9 mbar/sec (0.10 psi/sec). Transient fuel pressure stability requirement of 48.2 mbar/sec (0.70 psi/sec).Less gas pressure may result in reduced power. More gas pressure may result in instability.
Illustration 2 g00925714
Top view
Flow of fuel through the single turbocharger arrangement
(1) Fuel metering valve
Illustration 3 g00925717
Top view
Fuel flow through the twin turbocharger arrangement
(1) Fuel metering valve
Illustration 4 g01442860
Fuel flow through a low BTU arrangement
(1) Fuel metering valve The fuel flows to the electronically controlled fuel