Applies to the following parts of supply systems for the automatic liquid fuel supply of consuming units from one or more tanks: isolating valve, quick-acting valve, switch-over valve, forced switch-over valve, check valve, pressure compensating device, discharge valve, pressure reducer, filter, meter, de-aerator, anti-siphon safety device, pressure retaining device, isolation device, pressure gauge, vapour/air separator, pressure control path, combined part or other part.