The Mariotte tube provides a constant head of water for the flow tests when using the Double Ring Infiltrometer. The tube is supported by a cross channel which allows for field or lab use. Side graduations on the tube used to determining flow rate. Sealed adjusting tube allows raising or lowering the head inside the Infiltrometer ring. Bleed valve is located next to adjusting tube seal and main flow valve is located in base platform. Two sizes available -- 3,000 c³ or 10,000 c³ capacity. These will meet most requirements. Inquire about other capacities.