Car, Truck and Bus - ITEM 03 - FUEL TANKS AND REAR UNDERRUN PROTECTION
Base Regulation: 34 58
The legislation regarding fuel tanks is nearly harmonized, and is divided into sections pertaining to the installation of the tank and the performance of the tank itself. In addition, there are extra tests specifically for tanks made of a plastic material.
The installation requirements are primarily concerned with protecting the tank and preventing the entry of fuel into the passenger compartment. They may not form bulkheads (Directive section 5.5, Regulation section 5.1.6) and must be protected from impact with either vehicle parts or objects on the ground (D 5.10-11, R section 5.1.1.) Any fuel which does leak from the tank must fall to the ground (D 5.4 and 5.7, R 5.1.8 and 5.1.12), and there should be no build up of static electricity on the tank (D 5.11, R 5.1.9).
Also included in the installation requirements are sections on the strength and arrangement of all the connections to and from the tank (D 5.9, R 5.1.2, 5.1.3 and 5.1.4); basically all must be so constructed so as to withstand the rigors of life on the road.
The tanks themselves must withstand an entire battery of tests. Both the Regulation and the Directive require a hydraulic overpressure test (Both, section 6.1), and while the Directive requires an overturn test (6.2), the Regulation requires crash test validation of the installation. For the sake of expediency, VCA North America accepts the results of vehicle impact validation as proof of conformance for the fuel tank installation.
Plastic tanks are intensely scrutinized- there are tests for impact resistance (D 6.3.1, R Annex 5 section 1) and mechanical strength (D6.3.2, R Annex 5 section 2). After the test for permeability (D 6.3.3, R Annex 5 section 3), the tests for impact resistance and mechanical strength are repeated to show the degree of fuel resistance (D 6.3.4, R Annex 5 section 4).
There are also two tests which examine the performance of the tanks under high temperature conditions. The gentler of these is the test of resistance to high temperature (D 6.3.6, R Annex 5 section 6) which looks at tank deformation at high ambient temperature. The tougher one is the resistance to fire, (D 6.3.5, R Annex 5 section 5) which exposes tanks full of gasoline to flame for 2 minutes.
Currently, the Regulation pertaining to Rear Underrun (R58.02) does not pertain to N1 or M class vehicles, although extending to include N1 and M vehicles has been proposed. The directive (2000/8) does include N1 and M class vehicles, but is written in such a way that the normally present components of the vehicle perform this function. For N1, M, O1 and O2 vehicles, the simplest way to pass this requirement is to have ground clearance of less than 55cm over the full width of the vehicle (Annex II section 5.2). If this is not the case, then the evaluation indicated in Annex II section 5.3 (as applicable to N2/N3 & O2/O3 vehicles) must be performed.
N2, N3, O2 and O3 vehicles must be fitted with suitable underrun protection devices. Tests include strength testing, and dimension and positional checks. The force the rear protection device must withstand is proportional to the mass of the vehicle. Both system and component approvals are possible.
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