17 PIPES AND TUBES COMPRISED PRIMARILY OF PLASTIC FOR USE IN PLUMBING, CENTRAL HEATING SYSTEMS, AIR CONDITIONING, COMPRESSED AIR SYSTEMS, ELECTRICAL CONDUIT AND TELECOMMUNICATIONS TRUNKING, VACUUM SYSTEMS, UNDER-FLOOR HEATING, SOLAR HEATING SYSTEMS, INCLUDING SUN COLLECTORS, OUTDOOR PIPING AND FOR CONVEYING HOT AND COLD LIQUIDS INCLUDING WATER, REFRIGERANTS, GASES, INCLUDING COMPRESSED AIR, ELECTRICAL CONDUCTORS, FOOD STUFFS AND BEVERAGES; PARTS AND FITTINGS FOR ALL OF THE AFORESAID GOODS