Leak test of the valves

The leak test of the valves determines the leak rates of the CE valves. The test enables faulty valves to be determined.

The test must be carried out at least every 100 days!

If the test is not carried out after 100 days, the hydrogen refuelling is blocked.

Test requirements

The following requirements must be met:

• Tank pressure between 3.8 bar and 4.2 bar (absolute pressure)
  
• Vehicle stationary, handbrake engaged
  
• Engine runs without faults in the H2 mode and petrol mode
  
• Connect battery charger
  
• Furthermore, the safety regulations for repairs on the hydrogen vehicle must be complied with.
  

Test sequence

For the most part, the leak test is carried out automatically by the control unit. The test duration is approx. 30 minutes.

Procedure

• Turn of the vehicle and engage the handbrake
  
• Start the engine and run in the H2 mode
  
• The test module now checks whether all the test requirements have been met. Subsequently, the leak test is started.
  
• After the test start, the engine speed is increased to approx. 2000 rpm. This is required so that the changeover from H2 mode to petrol mode functions without difficulty.
  
• After the test start, the control unit closes the H2 valves. This interrupts the hydrogen supply to the engine.
  
• After approx. 10 to 20 seconds, the residual hydrogen in the lines has been consumed. The engine switches over to petrol consumption.
  
• After the changeover to the petrol mode, the engine can be switched off. However, at least terminal R must be switched on.
  
• The control unit checks the leak-tightness of the valves for approx. 30 minutes in cycles. During this time, the test module must not be terminated. Terminating the test module cancels the leak test.
  During this test phase, no user input is required.
  
• The leak test is completed after approx. 30 minutes. The determined leakage values are displayed in the test module.
  

Counter ”Number of days since the last boil-off test”

The counter is reset to ”0 days when the boil-off test starts. The counter cannot be reset if the tank pressure at the start of the boil-off test is greater than 4.2 bar (absolute pressure).