piston de refoulement à ressort

OBS: Le manomètre à ressort comprend un cylindre dans lequel se déplace un piston plein, équilibré par un ressort plat ou à boudin.

CONT: Surge Blocks.- Device that fits inside a well with a flexible gasket that is close in size to the inside diameter of the well. Attached to a rod that is raised and lowered with a stroke of about 3 feet. Surge block may be solid, vented or spring-loaded
OBS: A small spring loaded check valve was originally added to the surge block and the well developer could then remove the clays and silts from the well by ""pumping"" through the drop pipe, eliminating the need to bail or pump the well while surging.