A lab displacement vessel is a container used to measure the volume of a solid object, usually irregularly shaped, by displacing a liquid. The vessel is filled with a liquid, such as water, and the object is placed inside the vessel. The volume of the object can be calculated by measuring the amount of liquid that is displaced by the object, using a graduated scale or measuring cylinder.

The principle behind the displacement vessel is Archimedes’ principle, which states that the buoyant force on an object submerged in a fluid is equal to the weight of the fluid displaced by the object.

Lab displacement vessels are commonly used in materials science and engineering to determine the volume and density of solid materials, such as powders, pellets, and aggregates, which may have irregular shapes or voids. They may also be used in chemistry and biology to measure the volume and mass of small objects, such as cells or microorganisms.