+

D. Hydrogen Tank Valves Shut-Off
1.

Place wheel chocks to both front and rear passenger side wheels.

2.

Using a floor jack or suitable equipment, slightly raise the driver’s side of the vehicle to allow
for attachment of the Vent Manifold Assembly.

3.

Ensure the vehicle is securly supported. Use devices such as jack stands that are load rated
to safely support the Nexo.

4.

Remove the vehicle under covers to access the Hydrogen Tank Valves and High Pressure
Regulator. See service manual Nexo(Fe) > Hydrogen Storage System > Hydrogen Tank >
Repair procedures.
Floor under cover bolt torque : 7.8 - 11.8 N.m (0.8 - 1.2 kgf.m, 5.8 - 8.7 lb-ft

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5.

Close the manual valves on all three Hydrogen storage tanks using a 6mm hex socket (turn
clockwise) until fully seated in the closed position (flush with the valve body).

Manual Valve Locations

Manual Valve in Open Position

Manual Valve Operation

Manual Valve in Closed Position

E. Residual Pressure Release in Fuel Supply Line
1.

Unscrew the plug located in the Service Purge Valve at the High Pressure Regulator (HPR).

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2.

VENTING NEXO FUEL CELL ELECTRIC VEHICLES (FCEV)

Screw the Pressure Release Adapter into the Service Purge Valve.
Ensure the Pressure Release Adapter is fully seated in the Service Purge Valve.

HPR
Service
Purge
Valve

3.

Verify that both Manifold Assembly ball valves are closed.
Connect the Manifold Assembly to the Pressure Release Adapter quick disconnect.
Connect the vent stack hose to the Manifold Assembly red quick disconnect.

Ball Valves in Closed Position
Discharge Hose
to Vent Stack

Pressure Release
Adapter Quick
Disconnect

Red Quick Disconnect

While the vent hose is connected to the manifold assembly, no personnel should be allowed
into the safety circle
4.

Connect the discharge hose from the Manifold Assembly to the vent stack. Do not connect to
the discharge hose to any other venting system used for any other purpose.

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5.

VENTING NEXO FUEL CELL ELECTRIC VEHICLES (FCEV)

While holding the upper nut (24mm), turn the lower nut (19mm) on the Service Purge Valve
counter clockwise until the lower nut stops turning to open the service purge valve.

Service
Purge
Valve

6.

Using a Hydrogen leak detector, check for Hydrogen leaks at the fitting between the Service
Purge Valve and Manifold Assembly. Refer to the warning on Page 2 if a leak is suspected.

7.

Open the Manifold Assembly ball valve located in line with the Pressure Release Adapter and
a momentary hiss sound will be heard. After the hissing sound stops, close the Service Purge
Valve, then close the opened Manifold Assembly ball valve.
Closed Position

To Vent
Stack

Flow Path
from Service
Purge Valve

Turn
Counterclockwise to
Open Ball Valve

8.

Remove the Manifold Assembly and Pressure Release Adapter, then reinstall the Service
Purge Valve plug back into the Service Purge Valve.

F. Hydrogen supply tube disconnection using the release tool
1.

Slide the lock mechanism backwards employing a gentle rocking motion using needle nose
pliers or hands.
Hydrogen
Supply Tube

Lock Mechanism
Lock
Mechanism

Lock Mechanism

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2.

VENTING NEXO FUEL CELL ELECTRIC VEHICLES (FCEV)

Follow the instructions below to properly remove the Hydrogen supply tube.
Quick
Connector
Remover Tool.
See page 3.

1

Install the quick connector remover
tool onto the fuel pipe.

High Pressure
Regulator Fitting

2

Slide the quick connector remover tool into the High
Pressure Regulator Fitting until a click can be heard.

Tapered
Stopper

Hydrogen
Supply Tube

3

Pull the Hydrogen Supply tube out of the
High Pressure Regulator Fitting.

4

Install a clean stopper into the Hydrogen
supply tube to prevent contamination

G. Hydrogen Tank Venting
1.

NOTICE

Verify that both Manifold Assembly ball valves are closed.
Insert the Manifold Assembly vent tube into the High Pressure Regulator fitting where the
Hydrogen supply tube was removed. A clicking sound will be heard when the tube is fully
engaged and locked into the High Pressure Regulator Fitting. Pull back on the Manifold
Assembly vent tube to verify that the tube is locked into the High Pressure Regulator Fitting.
High Pressure
Regulator Fitting

Manifold Assembly
Vent Tube

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A clicking sound will be
heard when engaged

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2.

Using a 6mm male hex socket, turn the manual valve counterclockwise until the valve stops.
Fully reopen the manual valves on all three Hydrogen Storage Tanks.

Manual Valve in Closed Position

Manual Valve Operation

Manual Valve in Open Position

Manual Valve Locations

3.

Reconnect the auxiliary 12V battery negative (-) connector located in the rear cargo area.

4.

Press the Start/Stop button twice (Do not depress the brake pedal) to turn on the electrical
system (Accessory Mode). Do not start the fuel cell.

5.

Ensure the Hyundai GDS-M has the latest software update per TSB 15-GI-001 and that GDS
is fully charged.
Connect the GDS-M to the vehicle, select HMU (Hydrogen Management Unit). From Data
Analysis, select high pressure sensor, tank temperature for Front, Mid, Rear tanks.
Perform the HMU actuation tests (All Tank Valve Open).

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VENTING NEXO FUEL CELL ELECTRIC VEHICLES (FCEV)

Monitor tank temperature and pressure during the venting procedure, and graph Tank
Pressure and Tank Temperature for the Front, Mid, and Rear tanks.

6.

Gradually open the Manifold Assembly ball valve until the valve handle points to the red
discharge hose fitting. Regulate the venting flow with this valve.
Using a Hydrogen leak detector, inspect for Hydrogen leaks at all fittings between the Service
Purge Valve and Vent Stack Assembly. If Hydrogen leaks are suspected, stop (turn off) tank
valve actuation, allow Hydrogen to disperse then correct leak(s). Resume venting, repeat leak
check of fittings between the Service Purge Valve and Vent Stack Assembly.
(Arrow shape of ball valve handle points in direction of gas flow)
Hydrogen gas flows from Hydrogen
storage tanks to vent stack

Flow Path

Closed
Turn counterclockwise to open valve
and to adjust venting flow rate.

Use the Manifold Assembly ball valve to regulate the venting rate to depressurize the tanks at
145psi per minute, typically 1.55-1.65 MPa indicated on the manifold pressure gauge when
the tank pressure reads 435 psi on the GDS-M.
Monitor the tank pressure on the GDS-M, and adjust the venting rate so that the tank
depressurizes at 7 psi per minute using a watch with minute readout.

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Typical range
during defueling

If the tank temperature approaches -40F, stop venting or reduce the venting rate to maintain
tank temperature above -40F.

NOTICE
Vent tanks at 145 psi per minute until 435 psi is reached, then reduce venting rate to 7
psi per minute.
7.

Once the tanks have been vented to the desired amount, stop the actuation test and remove
the Manifold Assembly Vent Tube.
Reinstall the Hydrogen supply tube to the High Pressure Regulator fitting and install the
Hydrogen supply tube lock mechanism.
Using a Hydrogen leak detector, check for Hydrogen leaks at the HPR fittings and any repair
involving any part of the Hydrogen system.

8.

Reinstall all parts in reverse order of removal.

9.

Scan and clear DTCs in all systems.

10.

The service procedure is now complete.

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