In a building where the bus is located for maintenance, parking or other purposes, the following general rules are applicable:
1. Ensure that escaping hydrogen is vented
This can be done with the help of openings in the roof or by the use of (forced)
ventilation. Also, when hydrogen is detected, open a door to ensure supply of fresh air.
2. Avoid sparks
Either no electrical installation should be present above the heights of the hydrogen
tanks of the bus or it is switched off. At latest, it should be switched off when hydrogen is
detected. Also EX protected electric installations are allowed above the height of the
hydrogen tanks.
3. Ensure hydrogen leak detection (at a level of 40% lower explosion limit)
Either the building should be equipped with hydrogen leak detectors (standard detectors
with proven quality) or the hydrogen leak detection of the bus could be used together
with a manual hydrogen detector if it is for a short time and it is ensured that the
hydrogen leak detection of the bus works.
Hydrogen leak detection in the building should give a visible an audible alarm and the
controller of the alarm system should not be located in the same room as the bus.
4. Do not use the fuel cell system inside a building
Before entering a building the fuel cell must be switched off. This ensures at the same
time that the magnet valves of the hydrogen tanks are closed.
In addition, close the maintenance hydrogen valve in the bus whenever you enter a
building. This is a manually operable valve. It is located aside the refuelling nozzle in the
gastight cabinet. Note: With this valve closed, in case of an unintended startup of the
fuel cell system inside the building, hydrogen cannot be purged into the building.
5. Earth the doors
6. Personnel must be trained
The personnel that comes regularly in contact with the bus must be trained. Equivalently,
the bus must be accompanied by a trained person (driver, technician) if it is sent to
another location (e.g.for certification inspections).
7. Special measures to be for foreseen during overnight stay of the buses:
When not in service, the buses are standing on parking places with facilities to charge the
batteries. This is important, because the fuel cell needs to be permanently kept at
temperatures above zero and the hydrogen warning system is permanently on and,
therefore, the batteries might be discharged.
A document with safety considerations for maintenance facilities for FCEB's is written by Ballard.
