A Sounding Cock valve is fitted at the top of a sounding pipe on a ship. In nautical terms the word “Sound” is used to describe the process of determining the level in a tank or depth of water under a ship.

The sounding cock valve is opened and a sounding tape (tape measure with a weight on the end) is lowered into the sounding pipe. When the weight reaches the botom a reading is taken and then checked against the tank calibration book to find the quantity in the tank.

The sounding pipe usually extends almost to the bottom of the tank and has an open end. Because a Sounding Cock has a weighted lever you have to hold it open to take the reading and then releasing the lever will automatically close the valve.

Sometimes a foot pedal and lever is used to hold the valve open whilst you take a reading (as shown above).

There are other developments for determining the level in a tank including electronic and mechanical methods.