Explanatory notes
… action of a piston or plunger driven within a cylinder, the inlet and outlet being regulated by valves. “Single-acting” … utilise the thrust or suction of one end of the piston only; “double-acting” types pump at both ends of the piston … Subheadings 8413.11 and 8413.19 These subheadings cover only those pumps, of whatever type, which form, or have been …