Fuel Tubes and Fittings Replacement

REMOVAL
BEFORE REMOVAL: Due to the special service requirements required for these tubes, lines or fittings, also refer to the WARNINGS and CAUTIONS found in Fuel Tubes and Fittings Description and Operation.

INSTALLATION-HIGH-PRESSURE FITTINGS WITH NEW PRE-SET FITTINGS
New high-pressure lines with tube fittings are delivered completely assembled with the ferrule installed.

Special Go No-Go gauge inspection tools for Parker (TM) brand tube fittings are available from a Tube Fitting supplier. This will ensure that the high-pressure fitting has been sufficiently pulled up (tightened) on the fitting body. Use only a tool designed for Parker (TM) tube fittings.

Two different size fuel tubes are used on the high-pressure side of the CNG fuel system; 114 in. and 3/8 in. Use the correct size gauge inspection tool on the fitting.

Fig. 49 Assembling Fuel Tube And Fitting:

1. Insert fuel tube into fitting (Fig. 49). Be sure that fuel tube is completely through ferrules and resting firmly on shoulder of fitting body.
2. Tighten fitting finger tight.

Fig. 50 Marking Fitting Before Tightening:

3. After fitting has been installed finger tight, scribe or mark fitting at 6 O'clock position (Fig. 50).
4. Attach a backup wrench to fitting body. With a second wrench, rotate fitting 1/2 turn. Your scribe mark should now be at the 12 O'clock position.

Fig. 51 Go No - Go Tool Does Not Fit:

5. After fitting has been tightened, it must be checked with a Go No-Go gauge inspection tool. If gauge DOES NOT FIT between fitting and hex on fitting body, fitting has been properly tightened (Fig. 51).

NOTE: To prevent damage to fitting and tool, do not install Go No-Go gauge inspection tool to fitting while tightening. It is to be used only as a test gauge after fitting has been tightened.

Fig. 52 Go No - Go Tool Fits:

6. If gauge FITS between fitting and hex on fitting body (Fig. 52), additional tightening is required. Remove Go No-Go tool from fitting. Slowly continue to tighten fitting until gauge tool will not fit between fitting and fitting body. Do not over tighten fitting.
7. After installation and tightening, always leak test the component. Refer to Testing For Gas Leaks.

INSTALLATION-HIGH-PRESSURE FITTINGS WITH USED FITTINGS
Connections of used fittings can be made several times if the following steps are used:
1. Thoroughly clean tube and fitting before installation and tightening.
2. Insert fuel tube with pre-swaged, collapsed, ferrules into fitting body until ferrule seats into fitting body.
3. Tighten fitting nut by hand.
4. Attach a backup wrench to fitting body. Rotate fitting nut to its original position with a second wrench. An increase in resistance will be felt when fitting nut has reached its original position.
5. Slowly tighten fitting nut an additional one-twelve (1/12) turn. Do not over tighten fitting.
6. After installation and tightening, check fitting with Go No-Go gauge tool.
7. Leak test fitting. Refer to Testing For Gas Leaks for procedures.

INSTALLATION-LOW-PRESSURE FITTINGS/ COMPONENTS
When installing standard NPT tapered fittings to low-pressure side of fuel system, apply a small amount of anaerobic thread sealant to pipe threads only. Be extremely careful not to get any of thread sealant into any fuel system opening. Use only an anaerobic thread sealant containing Teflon (TM).

INSTALLATION-HIGH-PRESSURE FITTINGS EQUIPPED WITH O-RINGS
Fittings with O-rings are used on the high-pressure side of system at certain components.

Special precautions must be taken when removing/installing this type of fitting:
- Thoroughly clean tube and fitting before removal.
- Make sure both the threads and sealing surface are free of nicks, burrs, scratches or any foreign material.
- Lubricate O-ring with Parker (TM) O-Lube.

Fig. 53 Straight O-Ring Fitting:

- Tighten straight-type fittings (Fig. 53) to 28 Nm (245 in. lbs.) torque.
- Leak test the fitting. Refer to Testing For Gas Leaks for procedures.