Mariotte Tube

A Marriott tube is used to supply water to the top or bottom of a soil column (or some other device), while maintaining a constant pressure at the top or bottom of the column. The volume of water flowing out of the Mariotte tube and into the soil is measured by recording the change in water level in the Mariotte tube over time. The inside diameter of the Mariotte tube is 4.43 cm.

The inside cross-sectional area is therefore 15.4 cm². Thus a drop in water level of 1 cm, as read on the cm scale attached to the Mariotte tube, results in an outflow volume of 15.4 cm³.

The change in water level inside the Mariotte tube can be recorded manually from the cm scale attached to the tube, or can be recorded continuously, and accurately with a 1 psi (67 mbar) pressure transducer mounted at the top of the Mariotte tube. One psi pressure transducers are available from SMS.

Mariotte tubes are most often used in determining the saturated hydraulic conductivity of soil. An example of their use is found under saturated hydraulic conductivity.

Specifications:

Inside diameter: 4.43 cm

Inside length: 71 cm

Overall length: 85 cm