G3306B Petroleum Generator Set Engines Caterpillar

Adjusting the Positive Pressure Regulator

Natural Gas Positive Pressure Regulator

1. Turn the gas supply to the natural gas pressure regulator off.

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Illustration 1	g03605338
(1) Low-pressure side port (2) High-pressure side port

2. Connect 1U-5470 Engine Pressure Gp or 198-4240 Digital Pressure Indicator Gp to the engine.

   1. Connect the "High Pressure Side" of the gauge to the outlet port of the engine regulator upstream of the electronic fuel control valve.

   2. Connect the "Low Pressure Side" of the gauge to the tee fitting of the balance line on the regulator as shown in Illustration 1.

3. Install the 8T-5160 Gas Regulator Setting Tool if necessary.

4. Turn the gas supply pressure back on. Start the engine and operate at rated speed and no load.

5. Note the pressure differential on the pressure gauge. Compare the measured value to the value obtained previously in the Special Instructions, "Calculate the Engine Pressure Regulator Differential (dP)" section. If the values match, proceed to Step 9. If the values are different while using the 8T-5160 Gas Regulator Setting Tool , proceed to Step 6. If the values are different and the 8T-5160 Gas Regulator Setting Tool is not being utilized, proceed to Step 7.

6. Use the 8T-5160 Gas Regulator Setting Tool to adjust the regulator spring pre-tension until the measured and calculated differential pressure match. Proceed to Step 9 after the values match each other.

7. Shut down the engine and turn off the gas supply pressure.

   1. Remove the cap from the engine mounted gas pressure regulator.

   2. Adjust the regulator by adjusting the nut and/or screw with a screwdriver or similar tool.

   3. Replace the cap.

8. Turn on the gas supply pressure. Start the engine and operate at rated speed with no load.

   1. Compare the differential pressure reading with the calculated differential pressure.

   2. If the values match, proceed to Step 9. If the values do not match, repeat Step 7 to Step 8.

      ReferenceRefer to Testing and Adjusting, KENR6870, "Gas Pressure - Check and Adjust" for more information on adjust the regulator.

9. Replace the cap.

10. Stop the engine. Turn the gas supply to the regulator off.

11. Remove the lines for the differential pressure gauge and install the plugs back into the high and low side pressure locations.

12. Turn on the gas supply pressure and restart the engine.

Propane Positive Pressure Regulator

Illustration 2	g03605476
(1) Point A (2) Balance lines kept separate (3) Natural gas emission Adjustment screw (4) Balance line 1/2 inch diameter (5) Propane gas emission adjustment screw (6) Propane gas regulator (7) Solenoid valve (8) Vaporized propane gas (High BTU gas) (9) Manual shutoff valve or Solenoid valve and Pressure switch (10) Natural gas (Low BTU gas) (11) Pressure switch (12) Natural gas regulator (13) Fuel actuator (14) Carburetor (15) 5.5 inch ± 5 inch H2O differential here to Point A (16) 1.5-3.0 in H2O negative differential from here to Point A

1. Ensure that the gas supply to the propane gas pressure regulator is turned off.

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Illustration 3	g03606576
(1) Low-pressure side port (2) High-pressure side port

2. Connect 1U-5470 Engine Pressure Gp or 198-4240 Digital Pressure Indicator Gp to the engine.

   1. Connect the "Low Pressure Side " of the gauge to the port at the outlet of the propane regulator. The port should be upstream of the electronic fuel control valve and the propane emission adjustment screw as shown in Illustration 3.

   2. Connect the "High Pressure Side " of the gauge to the tee fitting by the balance line on the propane regulator as shown in Illustration 3.

3. Install the 8T-5160 Gas Regulator Setting Tool if necessary.

4. Turn the gas supply pressure back on. Start the engine and operate at rated speed and no load.

5. Note the pressure differential reading. The reading should be in the range of 1.5-3.0 inches in H²O.

   1. If the values match proceed to Step 9.

   2. If the values do not match while using the 8T-5160 Gas Regulator Setting Tool , proceed to Step 6. If the values do not match while not using the 8T-5160 Gas Regulator Setting Tool , proceed to Step 7.

6. Use the 8T-5160 Gas Regulator Setting Tool to adjust the regulator spring pre-tension until the measured and calculated differential pressures match. Once the pressures match, proceed to Step 9.

7. Shut down the engine and turn off the gas supply pressure.

   1. Remove the cap from the engine mounted gas pressure regulator.

   2. Adjust the regulator with the nut/screw with a screwdriver or similar tool.

   3. Replace the cap.

8. Turn on the gas supply pressure. Start the engine and operate at rated speed with no load.

   1. Check the measured differential pressure. If the reading is between 1.5-3.0 inches H²O, proceed to Step 9. If the measured differential pressure is not within the range, repeat Step 7 to Step 8. Repeat these steps until the measured and calculated differential pressures match.

9. Replace the cap.

10. Stop the engine and turn the gas supply to the regulator off.

11. Remove the lines for the differential pressure gauge and install the plugs into the low and high-pressure ports.

12. Turn on the gas supply pressure and restart the engine.

Set up for Automatic Switching Between Natural Gas/Field Gas and Propane

Note: The switchable dual fuel timing feature can only be used if the secondary fuel is propane. This system does not support any other type of fuel as the secondary fuel. Caterpillar does not guarantee the engine performance or emission compliance, if a fuel other than propane is used.

Illustration 4	g03605476
(1) Point A (2) Balance lines kept separate (3) Natural gas emission Adjustment screw (4) Balance line 1/2 inch diameter (5) Propane gas emission adjustment screw (6) Propane gas regulator (7) Solenoid valve (8) Vaporized propane gas (High BTU gas) (9) 1.5-3.0 in H2O negative differential from here to Point A (10) 5.5 inch ± 5 inch H2O differential here to Point A (11) Check valve (12) Manual shutoff valve or solenoid valve and pressure switch (13) Natural gas (Low BTU gas) (14) Pressure switch (15) Natural gas regulator (16) Fuel actuator (17) Carburetor

Note: Callouts (7) , (8) , (12) , (13) , and (14) are part of the OEM system.

The engine shipped from the factory is not configured to switch automatically between the two fuels. The customer is responsible for providing the input from the pressure switch (OEM supplied) to the Caterpillar supplied timing selection switch. Refer to Operation and Maintenance Manual, REHS9210 for guidelines on the engine setup to allow for automatic fuel switching.

Illustration 5	g03667098
(18) Timing selection switch

The engine timing is determined by the state of the timing selection switch (18) in Illustration 5. When the switch is Open, "First Desired Timing", is used as the desired timing for the engine. "First Desired Timing" can be configured using the ECMP panel. When the switched is Closed, "Second Desired Timing" is used as the desired timing of the engine. The "Second Desired Timing" is preset at the factory (22 degrees BTDC) and cannot be changed by the customer using the ECMP panel.

Note: The preset timing is for the propane fuel and ensures that the engine runs safely. No other fuel should be run on the secondary timing.

The input to the timing selection switch is provided by the pressure switch (14) located upstream of the natural gas/field gas solenoid (12) . This switch must be able to handle both field gas and natural gas. The switch must close below the deactivation pressure and should open the circuit above the natural gas/field gas activation pressure.

The activation pressure is chosen based on the gauge pressure for the fuel calculated in the "Natural Gas Positive Pressure Regulator" section. The pressure found in this section is required for full load operation.

The deactivation pressure is set around 3 to 4 psig below the activation pressure. The deactivation pressure can also be set to support the pressure needed for minimum acceptable load capability.

Note: If the generator set will operate at different altitudes over the service life, choose a switch that will work in all ranges. Under this scenario, a switch with an activation of 20 psig and deactivation of 15 psig may work best.

Before the engine can automatically switch between fuels, follow the procedure below to ensure emissions compliance when fuels are switched.

Note: The timing selection switch must be in the Open position when perform the procedures below.

1. Follow the "Natural Gas Positive Pressure Regulator" section to set up the engine on natural gas/field gas.

2. Determine the "Fuel Valve" position in the ECMP panel.

   1. Go to "Menu".

   2. Select "Configure".

   3. Select "All Set Points".

   4. Select "Engine Configuration Parameters".

   5. Select "Air Fuel Ratio Control".

3. Follow the "Propane Positive Pressure Regulator" section to set up the engine for propane.

4. Once the engine emissions are set, make minor adjustments to the propane adjustment screw. The propane fuel valve must operate in the same range as the range viewed for natural gas above.

Once the steps above are completed, the "First Desired Timing" should return back to the determined timing from Testing and Adjusting, "Timing - Calibrate". The engine can now switch automatically between natural gas/field gas and propane depending on the input to the timing selection switch.