Series 50 – Section 2.43 Venting and Leak Checking Procedures for a Natural Gas Engine (Low Pressure System)

Section 2.43
Venting and Leak Checking Procedures for a Natural Gas Engine (Low Pressure System)

Refer to "2.43.1 Venting an Operable Engine to Relieve Natural Gas Pressure" for venting and checking of an operable engine and refer to "2.43.2 Venting an Inoperable Engine to Relieve Natural Gas Pressure" for venting and checking of an inoperable engine.‪

Section 2.43.1
Venting an Operable Engine to Relieve Natural Gas Pressure

If the engine can run , use the following venting procedure to relieve the natural gas pressure downstream of the shutoff valve:‪

EXPLOSION ‪
To avoid injury from the explosion of natural gas, the engine must be kept in a well ventilated area away from open flames, sparks, and electrical resistance (heating) coils.‪

1. Turn off manual shutoff valve on natural gas fuel supply line.
2. Start engine and run until it stalls due to fuel starvation.
3. Disconnect the batteries using switch(s) in the battery compartment or by disconnecting the battery ground cable.
4. Slightly loosen the NG fuel line fitting to be serviced in a well ventilated area to allow any remaining gas to vent.
5. Completely open the fitting that was slightly opened and allow to vent in a well-ventilated area.

Section 2.43.2
Venting an Inoperable Engine to Relieve Natural Gas Pressure

If the engine cannot run , use the following venting procedure to relieve the natural gas pressure downstream of the shutoff valve:‪

EXPLOSION ‪
To avoid injury from the explosion of natural gas, the engine must be kept in a well ventilated area away from open flames, sparks, and electrical resistance (heating) coils.‪

1. Turn off manual shutoff valve on natural gas fuel supply line.
2. Disconnect the batteries using switch(s) in the battery compartment or by disconnecting the battery ground cable.
3. Open fitting (before and after genset shut-off valve) to assure all pressure has been relieved in the natural gas fuel line.
4. Check all connections that were loosened for leaks after installation, service and troubleshooting are complete.

Section 2.43.3
Leak Checking the Natural Gas Fuel System

Use the following steps to check for leaks:‪

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.

1. Open manual shutoff valve.

   EXPLOSION ‪
   To avoid injury from the explosion of natural gas, the engine must be kept in a well ventilated area away from open flames, sparks, and electrical resistance (heating) coils.‪

2. Start engine and run with no electrical load on generator.
3. Spray soapy water or commercially available leak checking solutions on connections. Bubbles will form if there is a leak.
4. Repair any leak by:
   1. Shut down the engine and close the manual shutoff valve.
   2. Tightening connection using the fitting manufacturer's technique.

   Note: Vent fuel lines before replacing leaking components; refer to and refer to . This will prevent a discharge of gas.

   3. Replacing leaking component.
   4. Replace the pipe threaded connector with a new one if the leak is a pipe thread connection. Use anaerobic sealant with Teflon (such as SWAK®) applied to the threads.

      SWAK® is a registered trademark of the Cajon Company.‪

5. Re-check connection with procedure in step 1 thru step 3 .
6. Use a combustible gas detector to check for presence of natural gas. If natural gas is detected, continue looking for leaks until the locations of all the leaks are determined.
7. Repair the leak using the procedure in step 4 .