What legal requirements apply to methane cylinders?

Pursuant to the Italian Ministry of Infrastructure and Transport Circular (Prot. 131_MOT2/C, 13 January 2006), methane cylinders that comply with EU standards (ECE/ONU n. 110) now need regular servicing every 4 years, instead of every 3 years as before.
The efficiency and physical condition of other types of cylinder must be tested every five years, as before, to ensure maximum safety (Law 7 June 1990 no. 14; Presidential Decree Law. 9 November 1991 no. 404).
Note that subsequent cylinder testing by S.F.B.M. (Servizi Fondo Bombole Metano) is free of charge apart from the cost of removing and reinstalling cylinders after testing.