SB-10054513-7897

INSTRUCTION TO SERVICE
ITS: 5533
SECTION:

241

WRITTEN BY:

Mike Pearson

SUBJECT:

Relocation of Excess Flow Valve on Rear CNG Roof Pack Assembly (XN60)

Fuel System

ITS5533

THIS DOCUMENT AND THE CONTENTS DISCUSSED HEREIN ARE THE CONFIDENTIAL AND
PROPRIETARY INFORMATION OF NEW FLYER INDUSTRIES CANADA ULC AND NEW FLYER OF
AMERICA INC. AND ARE DISCLOSED BY NEW FLYER IN CONFIDENCE. THIS DOCUMENT AND THE
CONTENTS HEREIN ARE NOT TO BE DISCLOSED BY THE INTENDED RECIPIENT WITHOUT THE PRIOR
WRITTEN AUTHORIZATION OF NEW FLYER. ANY UNAUTHOIZED DISCLOSURE, REPRODUCTION OR
OTHER DISTRIBUTION OF THIS DOCUMENT OR INFORMATION IS STRICTLY PROHIBITED AND MAY
RESULT IN ACTION BEING TAKEN AGAINST THE PARTY MAKING THE UNAUTHORIZED DISCLOSURE.
THIS DOCUMENT AND ALL COPIES HEREOF MUST BE RETURNED TO NEW FLYER UPON REQUEST.

Venting preparation:
WARNING:

Only qualified high pressure gas certified service personnel should work on
compressed natural gas fuel systems.

WARNING:

The presence of ignition sources may lead to an explosion hazard. DO NOT use jumper
wires from an external power source to energize tank solenoid valves during venting
process.
DO NOT leave the vehicle unattended during the venting process. Ensure all shut-off
valves are properly locked out or tagged so as to prevent inadvertent opening of a
valve during the venting process. Ensure that the high pressure gauge is tagged to
identify high pressure within the system whenever Zone One or Zone Two areas have
been vented.
DO NOT vent gas directly from the surge line shut-off valve directly to atmosphere.
Ensure that the discharged gas is connected to a recovery system or is safely
redirected through a vent stack in accordance with local environmental regulations.

NOTE:

Prior to conducting any venting activity ensure the following steps are followed:
a.

Minimize the pressure in the fuel tanks by driving the vehicle, if practical, to use up as
much of the fuel as possible.

b.

Perform the venting procedure outdoors.

c.

Allow adequate time for the exhaust system to become cool to the touch.

d.

Provide a direct ground for the purge line and for the recovery system to dissipate
static charges that may build up during venting. Use a No. 3 gauge wire to connect to a
suitable ground such as a water main or a pipe that is installed 8 feet (2.4 M) into the
ground.

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PROCEDURE:
1. Turn the Battery Disconnect switch to the OFF position.
2. Open the battery access door and locate the fill box and main (emergency) shut-off valve.

1

Figure 1: Fuel System Venting Zones

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3. Zone One Venting Procedure:
a.

Close the main fuel supply by rotating the main (emergency) shut-off valve to the fully closed (horizontal)
position. See Figure 2.

b.

Connect a line from the recovery system to the purge line shut-off valve. See Figure 2.

c.

Slowly rotate the purge line shut-off valve to the fully open (vertical) position. See Figure 2.

d.

Allow the lines between the pressure regulator and the main (emergency) shut-off valve to completely
depressurize as indicated by a “zero” reading on the high pressure gauge and no further flow through the
vent line. See Figure 2.

e.

Open the rear engine compartment door and locate the CNG low pressure fuel filter located on the
underside of the rear shelf above the engine. See Figure 1.

f.

Locate the drain cock or fitting on the bottom of the secondary fuel filter. See Figure 1.

g.

Carefully crack open but do not remove the drain fitting, and allow the lines between the engine and the
pressure regulator to fully depressurize as indicated by a zero reading on the low pressure gauge.

CAUTION:

The area immediately upstream of the main (emergency) shut-off valve is still
pressurized even though the high pressure gauge reads “zero”. Only the Zone One
area has been depressurized. Ensure that the high pressure gauge is tagged to
indicate this condition and that the main shut-off valve is locked out to prevent
inadvertent opening during maintenance or repair.

Figure 2: Fill Box

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4. Zone Two Venting Procedure:
a.

If a Zone One Venting Procedure was performed the technician is to make sure to close the fuel filter
drain if it was opened during the Zone 1 venting procedure.

b.

Close the manual lockdown device on all fuel tank solenoid valves. Torque the lock-down stem (3/16”
Allen or Socket Hex) to 60 to 84 in*lb (6.7 to 9.5 Nm). See Figure 3.

c.

Ensure the main (emergency) shut-off valve and the manual fuel tank isolation shut off valves (if
equipped) are open. See Figure 2.

d.

Connect a line from the recovery system to the purge line shut-off valve. See Figure 2.

e.

Slowly rotate the purge line shut-off valve to the fully open (vertical) position. See Figure 2.

f.

Allow the gas in Zone Two to completely depressurize as indicated by a “zero” reading on the high
pressure gauge and no further flow through the vent line. Figure 2.

g.

Close main shut-off valve

h.

Monitor high pressure gauge for 10 minutes to make sure there are no leaks from zone 2.

CAUTION:

The fuel tank solenoid valves, pressure relief devices, and fuel tanks are still
pressurized even though the pressure gauge reads “zero”. Only the Zone One and
Zone Two areas have been depressurized. Ensure that the pressure gauge and fuel
tank solenoid valves are tagged to indicate this condition and that the shut-off valve is
locked out to prevent inadvertent opening during maintenance or repair.

Figure 3: Manual Lockdown of Fuel Tanks

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5. Using approved fall safety protection equipment; locate the excess flow valves on bus roof. See Figure 4.
6. Verify excess flow valve direction. Arrows should both be pointing towards hose. If not, the front module will
need to be corrected. The rear will be corrected during the following steps. See Figure 4.

Front CNG Assembly

Rear CNG Assembly

Valve to be relocated
to rear roof pack

Figure 4: Verify CNG Flow Valve Directions

7. If the excess flow valve directions are correct, from the rear CNG assembly remove and discard the ¾” SST
supply tube p/n 412305 and ferrules. See Figure 5.
Rear CNG Assembly

Leave existing reducing
Tee tube fitting installed

Remove and discard the
¾” SST supply tube p/n
412305 and ferrules.

Leave existing union
Tee tube fitting installed

Figure 5: Remove Rear CNG Assembly Supply Tube

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8. Remove the ¾” SST supply tube p/n 486630 and ferrules, reducer port p/n 041667, excess flow valve p/n
448308 and the port adapter p/n 065358 at rear of artic joint fuel hose, discard all parts but save the excess
flow valve for reuse, do not remove the Bulkhead fitting (See Step 9). See Figure 6.
Existing Artic joint
fuel hose

Rear CNG Assembly

Do not remove the
Bulkhead fitting
Remove and discard
the port adapter p/n
065358
Remove the excess
flow valve p/n 448308
and save for reuse
Remove and discard
the reducer port p/n
041667
Remove and discard the
¾” SST supply tube p/n
486630 and ferrules.
Figure 6: Remove Parts at Rear of Artic Joint Fuel Hose
9. On the rear assembly install new reducing port connector p/n 065358, and nut p/n 116717 to both tee fittings
and install the excess flow valve p/n 448308 removed in Step 8 in the orientation shown using new ½” ferrule
p/n 116713 and nut p/n 116716 as shown in Figure 7 & 7a. See pages 10 and 11 for correct Swagelok®
fitting installation instructions.
Nut p/n 116717
Reducing port
connector p/n
065358
Nut p/n 116716
& ferrule set p/n
116712
Excess flow
valve p/n 448308
Nut p/n 116716
& ferrule set p/n
116712
Reducing port
connector p/n
065358

Figure 7: Excess Flow Valve Direction

Nut p/n 116717

Figure 7a: Section of Assy Sequence

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10. Install new ¾” SST line p/n 526305 at rear of artic joint fuel hose as shown in Figure 9 using ¾” ferrule p/n
116713 and nut p/n 116717. See pages 9 and 10 for correct Swagelok® fitting installation instructions.
NOTE:

One leg of the ¾” SST line p/n 526305 is ¼” longer than the other. The longer leg should go
into the existing bulkhead fitting.

Nut p/n 116717
& ferrule set p/n
116713
Nut p/n 116717
& ferrule set p/n
116713

New ¾” SST line
p/n 526305

Longer leg of the
SST line goes to
existing
bulkhead fitting

Figure 9: Install New Supply Tube at Rear of Artic Joint Fuel Hose
11. Close the Secondary Filter drain cock, See Figure 1.
12. Close the Purge Line Shut-off Valve, See Figure 10.
13. Turn the Quarter-turn Main Shut-off Valve handle to the open position. The handle is in the open position
when it is aligned (parallel) to the fuel line, See Figure 10.

Fig. 10: Fill Box

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14. Open the manual lockdown device on all fuel tank solenoid valves. Torque the lock-down stem (3/16” Allen or
Socket Hex) to 60 to 84 in*lb (6.7 to 9.5 Nm). See Figure 3.
NOTE:

Make sure the fill box door is firmly closed before attempting to start the engine. The fill
box contains a proximity sensor to prevent the engine from starting when the door is
open. The engine ignition is disabled and the high-pressure solenoid valves are shut off to
prevent fuel flow to the gas mixer when the proximity sensor is open.

15. Turn the main battery disconnect switch to the “ON” position. Turn the ignition on to activate the starter. The
solenoid valves will then energize and allow fuel to flow through the filtering and regulating system to the fuel
mixer, starting the engine.
16. Run the engine up for 5 – 10 seconds to allow the fuel delivery system to stabilize and then shut the engine
down.
17. Open the fill box door and check the high and low pressure gauges for pressure readings. The high pressure
gauges should show 200 to 3,600 psi (1,375 to 24,800 kPa), the low pressure gauge should show 99 to 125
psi (683 to 863 kPa). See Fig. 4.
18. Check all replaced parts and connections for leaks using a combustible gas detector such as the Snap-On
ACT 8800®. This particular unit can detect localized gas leaks from 50 to 1000 PPM.
NOTE:

Liquid solutions such as SNOOP® can also be used.
soapy water solutions.

DO NOT use make-shift

19. Close interior battery access door.
20. Close the rear engine compartment door.
21. Close exterior access doors.

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LABOUR ESTIMATE
Operation
1

Relocation of Excess Flow Valve on Rear CNG Roof Pack

Men

Hours

1

3.0

Labour Time
M X HR
3.0

Assembly (XN60)

PARTS REQUIRED
Description

Qty.
per
Coach
1

Units

Item

Part Number

Notes

1

526305

Tube 0.75 OD SST CNG

2

065358

Connector-3/4-1/2 Port

2

EA

3

116712

Front & Back Ferrule-1/2” OD SST Tube

2

EA

Vpn SS-810-SET

4

116713

Front & Back Ferrule-3/4” OD SST Tube

2

EA

Vpn SS-1210-SET

5

116716

NUT-1/2” OD SST TUBE

2

EA

Vpn SS-812-1

6

116717

NUT-3/4” OD SST TUBE

4

EA

Vpn SS-1212-1

EA

SPECIAL TOOLS REQUIRED
Item

Part Number

Description

Qty.
per
Coach

Notes
Units

No Special Tools Required.

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