Matthias Moeller is Senior Technical Advisor at Prolyte GroupOther blogs by Matthias Moeller
Can I combine with brands that say they have “Prolyte compatible” truss?
From a distance all trusses look the same. On closer examination, however, differences become apparent. Joining together trusses from different manufacturers places a high risk of liability on different parties: the user, the employer, the owner and the manufacturer/distributor. This risk is based on the effect of different legal spheres such as product safety, product liability, warranty and reliability as well as stability and load bearing capacity.
The connection of trusses from different manufacturers is almost impossible from a legal point of view. The person who connects trusses from two manufacturers is directly considered to be the manufacturer of a new product, as it can be excluded that both manufacturers confirm that their products are compatible with competing products. The user who connects trusses from different manufacturers directly becomes the manufacturer of a new product and is subject to the General Product Safety Directive 2001/95/EC.
The Prolyte Group explicitly states that Prolyte trusses may not be connected to the trusses of any other manufacturer. According to the directive on liability of defective products 1999/34/EC, the manufacturer is the person who imports or distributes a product for the purpose of sale, hire, leasing or any form of distribution for economic purposes in the course of their business within the scope of the agreement on the European Economic Area. If the manufacturer of the product cannot be determined, then each supplier is considered as the producer thereof.
Example: A truss used as a lifting accessory with a length of 7m, assembled of trusses from different manufacturers (type A + type B) is rented. Liability for both manufacturer's is excluded to the directive on liability of defective products 1999/34/EC, if the partial products (type A and type B) itself are flawless and a fault is only created by the manufacture of the final product. In case of damage, only the person who has manufactured the final product will be liable. Which in this example, is the user!
If an employer provides a set of trusses from different manufacturers to an employee as work equipment (e.g. lifting accessory), the employer is responsible for the safety of the work equipment in accordance with the European Directive on the minimum safety and health requirements for the use of work equipment by workers at work 2009/104/EC:
The employer shall take the measures necessary to ensure that the work equipment made available to workers in the undertaking or establishment is suitable for the work to be carried out or properly adapted for that purpose and may be used by workers without impairment to their safety or health.
The Prolyte Group explicitly states that a risk assessment for an assembled truss provided and used as working equipment must always include a proof of the stability and load bearing capacity. The Prolyte Group rejects any warranty claims that may be derived from damage due to improper connection of Prolyte trusses with elements from other manufacturers. With regard to the stability and load bearing capacity of assembled trusses from different manufacturers, we explicitly point out that even the smallest tolerances in the connection elements can drastically affect the load bearing capacity. Due to differences in dimensions (diameter, cone angle, length) of the connecting elements, the transmittable forces in a connection between two different trusses (e.g. by bending the bolts subsequent to large distances between the inner radius of the cylindrical part of the cone bushings and outer radius of the cylindrical part of the cone connector) can be reduced to a fraction of the values assumed for the systems. Example: If the cone connector has too much play in a too large cone bushing, the tapered bolt is easily overloaded by bending.
The Prolyte Group explicity states that Prolyte trusses must not be connected with truss elements from other manufacturers!
The widespread opinion, that with the connection of trusses from different manufacturers the loading data of the weaker truss are considered as sufficiently secure, is free of any physical and legal basis. Different material properties and manufacturing processes lead to different allowable internal forces of the various truss types. An individual proof of the stability and load bearing capacity of assembled trusses from different manufacturers would therefore always be required. This cannot be reasonably implemented in daily practice. The Prolyte Group expressly states that Prolyte trusses must not be connected with truss elements from other manufacturers!